# Chemical Calculations (Stoichiometry)

## Objectives

Upon completion of this lesson, the students should be able to:

1. describe a mole
2. determine molar and molecular masses
3. calculate the percentage composition of a compound
4. calculate the empirical and molecular formulas

## Introduction

The branch of chemistry, which deals with the numerical relationships of elements and compounds and the mathematical proportions of reactants and products in chemical transformations, is known as stoichiometry. An understanding of the mole concept together with some skills in writing and balancing chemical equations enable us to solve stoichiometric problems involving mass relations of reactants and products in chemical reactions.

## The Mole Concept

In chemical calculations it is necessary to consider quantities of substances in terms of the number of atoms, ions or molecules present. The unit devised by chemists in expressing these numbers of atoms, ions, or molecules is called the mole.

Mole is the unit of measurement used in chemistry in expressing amounts of a chemical substance. It has a value of 6.02214129(27)×1023elementary entities of the substance. Chemists use mole to express the amounts of reactants or of products in chemical reactions instead of units of mass or volume.

A mole is defined as that quantity of a substance that contains the same number of ultimate particles (atom, ions, or units of ions) as present in 12g of Carbon -12.

## What is molar mass?

The molar mass is the sum of the masses of the atoms present in one mole of a substance, which can be an element or a compound. It can be expressed as a unit of mass per mole like grams/mol, kg/mol.

Examples:
1. Find the molar mass of: Al, H2O, Ca(OH)2
a. Al = 27 g/mol

b. H2O = 18 g/mol

H = 2 at x 1g/mol = 2g O = 1 at x 16g/mol = 16g 18g/mol

c. Ca(OH)2­ = 74 g/mol

Ca = 1 at x 40g/mol = 40g O = 2 at x 16g/mol = 32g H = 2 at x 1g/mol = 2g 74g/mol

2. How many moles are present in: 5.4 g of Al, 180 g of H2O?

a. 5.4 g x 1 mol/27g = 0.2 mol b. 180 g x 1 mol/18g = 10 mol

3. What is the mass of: 5 mol of Ca(OH)2 and 2 mol of Al ?

5 mol of Ca(OH)2

Ca = 1 x 40 = 40 O = 2 x 16 = 32 H = 1 x 2 = 2 74g 5 mol x 74g/mol = 370g

2 mol of Al

Scroll to Continue

2 mol x 27g/mol = 54 g

The number of molecules in a mole of any molecular substance is the same as the number of atoms in a gram-atom of any number. This number of atom is called the Avogadro’s number, the accepted value of which is 6.02214129(27)×1023 atoms/gram-atom of any element. In other words, a mole is the amount of substance that contains as Avogadro’s number of particles equal to 6.02214129(27) ×1023 or simply expressed as 6.02 x 1023. The particles can be atoms, molecules, or ions.

Examples:

There are 6.02 x 1023 atoms in 1 mol of carbon

There are 6.02 x 1023 molecules in 1 mol of H2­O

There are 6.02 x 1023 Na

6.02 x 1023 Cl in 1 mol of NaCl

## Mole

Unit systemInternational System of Unit (SI base unit)

Unit of

Amount of substance

Symbol

mol

## Examples:

1. How many atoms are present in:

a. 5 mol of copper

5 mol x 6.02 x 1023 atoms/mol = 30.10 or 3.01x 1023 atoms

b. 48 g of carbon

48 g x 1 mol/12g x 6.02 x 1023 atoms/mol = 24.08 x 1023 or 2.408 x 1023 atoms

2. How many g of H2O will contain 3.01 x 1024 molecules?

3.01 x 1024 molecules x 1 mol/6.02 x 1023 molecules x 18 g/mol = 90g

## Percentage Composition

Percentage composition is a statement indicating the percentage of each element present in a compound. In chemistry, this composition is always on a weight basis unless specifically stated otherwise. Sometimes the composition of the mixture of gases is given on a volumetric basis. The computation of the percentage composition from the formula of the compound is based upon the meaning of the symbols and formulas. Each symbol stands for one atomic weight’s worth of the element it represents, and each formula stands for one molecular weight’s worth of the compound it represents.

1. What is the percentage composition of water?

% H = 2g/18g x 100% = 11.11% % O = 18g/18g x 100% = 88.89% 100.00%

2. What is the percentage composition of H2SO4?

% H = 2g/98.1g x 100% = 2.0% % S = 32g/98.1g x 100% = 32.7% % O = 64g/98.1g x 100% = 65.3% 100.0%

## Empirical Formula

Empirical Formula is a chemical formula denoting the constituent elements of a substance and relative number of atoms of each. It gives the simplest ratio of the number of the atoms.

Example:

What is the empirical compound formula of a compound which contains 2.05% H, 32.65% S, and 65.30% O?

Basis: 100 g of the compound

H = 2.05/100 x 100 g = 2.05 g X 1 at/1g = 2.05 at

S = 32.55/100 x 100 g = 32.65 g x 1 at/32g = 1.02 at

O = 65.30/100 x 100 g = 65.30 g x 1 at/16g = 4.08 at

The formula is not H2.05 S1.02 O4.08. Subscripts are small whole numbers, but they are not rounded off but are divided by the smallest number. The correct formula is H2SO4

H2.05 ­ S1.02 O4.08 = H2SO4

## Molecular Formula

Molecular formula is a chemical formula denoting the constituent elements of a substance and the number of atoms of each composing one molecule. It gives the actual ratio of the number of the atoms in a mole of the compound.

Example:

A compound is 85.69% C and 14.31% H. If the molar mass is 56 g/mol. What is the molecular formula of the compound?

Basis: 100 g of the compound

Determine the empirical formula:

C = 85.69 g x 1 at/12 g = 7.14 at

H = 14.31 g x 1 at/1 g = 14.31 at

Empirical Formula = C7.14 H14.31/7.14 = CH2

## Self-Progress Test:

Part I

Solve the following:

1. What is the mass in grams of:
1. 2 moles of AlCl3
2. 8 moles of CaCO3
3. 5 moles of (NH4)2SO4
4. 4 moles of C6H12O6
5. 3 moles of KNO3

## Part II

1. Calculate the number of moles in each of the following:
1. 68.4 g of sucrose C12H22H11
2. 80 g of NaOH
3. 3.01 x 1023 atoms of Al
4. 6.02 x 1024 molecules of CO2
5. 12 g of O2

## Part III

1. Find the percentage composition of the following:
1. Sugar C12H22O11
2. hydrated copper sulfate CuSO4 5HO
3. sulfuric acid H2SO4
4. hematite Fe2O3

jeriemaedlcrz25 on August 21, 2018:

Jeriemae Dela Cruz bsmt-1

The balance equations is the main basis of stoichiometry, and that is the first thing to do when you want to measure a chemical process. The information provided by the chemical equation is interpreted according to the needs.

Abe Puzon on August 21, 2018:

Krichelle Kae Enriquez, BSMT-1

Learning stoichiometry helps us med tech student to gain more knowledge. This will help us to go to another level of learning. Not only us can gain knowledge but also others who wanted to learn more.

Abe Puzon on August 21, 2018:

Puzon, Abegail S. BSMT-1

In this lesson, we Medical Technology student learned the importance of understanding a problem and dividing it into manageable sub-problems. We felt comfortable that we would know what to do with the stoichiometry part of a question. Once we grasped the available information, we felt more comfortable in setting the stoichiometry aside while we worked on some other aspect of the information that would allow us to either find moles of the “given” substance or the required measure of the “unknown” substance.

trixie anne on August 21, 2018:

SILVESTRE, TRIXIE ANNE C. BSMT 1, With the Stoichiometry you can know what the substances are like before and how they will be after the chemical reaction. All reactions depend on the amount of things they have. Stoichiometry helps you determine the amount or proportion of compounds you will need in a chemical reaction. The reactions depend on the compounds involved and how much of each compound is needed to determine the product that will result.

De Leon Melody Jane S. on August 21, 2018:

This lesson is very an effective tool for us to learned or to gained knowledge about stoichiometry. It will be not for us to be difficult to find another links of what this topic is all about. Stoichiometry is an application of the laws of conservation of mass and enerygy to chemical activity. This is an equation to know the number of moles and its percentage. As a future medical technologist it is very useful for us to have an accurate results for our patients because of this knowledge.

Nhiza Mae Fajardo on August 21, 2018:

FAJARDO, NHIZA MAE A. BSMT-1

This lesson is very relevant to a medical technology student like me. Stoichiometry deals with the application of the laws of definite proportions and of the conservation of mass and energy to chemical activity. The article helped us a lot because this will help a medical technology student or a medical technologist to perform laboratory works accurately.

Fajardo, Nhiza Mae A. on August 21, 2018:

FAJARDO, NHIZA MAE A. BSMT-1.

This lesson stoichiometry is relevant to us medical technology students. The article has given us the informations needed by a medical technologist so that we will perform laboratory works accurately with the help of this lesson.

Pascual, Mary Angelou C. on August 21, 2018:

Pascual, Mary Angelou C. BSMT1. As a medtech student stoichiometry is a big help for us. Stoichiometry discuss also the moles, molecular mass, molar mass, avogadro's number and percentage composition. This topic gives us a new knowledge that we will use in our future.

Joyce Nicole on August 21, 2018:

DUNGO, JOYCE NICOLE B. BSMT-1 Stoichiometry is important because it allows us to predict how much of reactant is consumed in a chemical reaction, or how much unwanted product is being generate. Studying stochiometry will help us a lot in the future because it can be applied in the field of medicine specially in manufacturing of drugs.

Joyce Nicole on August 21, 2018:

DUNGO, JOYCE NICOLE B. BSMT-1 Stoichiometry is important because it allows us to predict how much of reactant is consumed in a chemical reaction, or how much unwanted product is being generate. Studying stochiometry will help us a lot in the future because it can be applied in the field of medicine specially in manufacturing of drugs.

Joyce Nicole on August 21, 2018:

DUNGO, JOYCE NICOLE B. BSMT-1 Stoichiometry is important because it allows us to predict how much of reactant is consumed in a chemical reaction, or how much unwanted product is being generate. Studying stochiometry will help us a lot in the future because it can be applied in the field of medicine specially in manufacturing of drugs.

Joyce Nicole on August 21, 2018:

DUNGO, JOYCE NICOLE B. BSMT-1 Stoichiometry is important because it allows us to predict how much of reactant is consumed in a chemical reaction, or how much unwanted product is being generate. Studying stochiometry will help us a lot in the future because it can be applied in the field of medicine specially in manufacturing of drugs.

Kimberly Reforsado on August 20, 2018:

Through this topic, I am able to learned what is a mole, determine the molar mass as well as molecular mass and calculate the percentage composition of a substance or compound. As a student who is pursuing Medical Technology, studying Stoichiometry will help me a lot in my future profession because it essential for us to determine the right proportions of reagents that will be used in our work which is what stoichiometry is all about.

Emman Payuran on August 20, 2018:

VILLASENOR, EMMANUEL P.

BSMT1

The skills we will get from learning how to do stoichiometry problems are probably the most important thing to take away from a chemistry class. Dimensional analysis (aka. unit cancellation) will help you in every single science class you ever take - especially physics - and can often help you get a correct answer on a problem you don't completely understand as long as you know your answers has the correct units.

John Derrick Chan on August 20, 2018:

CHAN, JOHN DERRICK L. BSMT1. As a medical technologist, stoichiometry is really helpful since, we are going to deal with reagents wherein we need to know the right amount that we are going to put to make the results accurate. In this lesson, it can let us to analyze the substances to be mixed to create an outcome that is precise and accurate based on their composition. Moreover, not only it can be used on that but also on the following experiments that we will done that we need to deal with an exact amount of reactants.

kathlenecalague on August 20, 2018:

CALAGUE KATHLENE JADE R. BSMT 1 Stoichiometry lets us to predict results of a chemical reactions. It is used to determine the amount of reactants needed to produce reaction. So as a future medical technologists, we can use the informations we gained by the use of this article in order to perform accurately specially on lab experiments at our future jobs.

Elaine Herrera on August 20, 2018:

HERRERA, MARY ELAINE V. BSMT Stoichiometry is the process of calculating the relative quantities of reactants and productsin chemical reactions. As a Medical technology student, this article was helpful in educating about this branch of chemistry, which deals with the numerical relationships of elements and compounds and the mathematical proportions of reactants amd products in chemical transformations. This article was really relevant and understandable for me.

Jimelle Conson from Bulacan on August 20, 2018:

CONSON, JIMELLE - BSMT 1. Learning about Stoichiometry enables me to know more about chemical reactions. Stoichiometry deals with the mathematical proportions of reactants and products in chemical transformations. This page helped me to gain more knowledge about solving problems that involves different chemical formulas.

PatriciaMae Sayco on August 20, 2018:

SAYCO, PATRICIA MAE M. BSMT 1 Stoichiometry is very important to understand the relationship between the reactants and products in chemical reaction. Usually future Medical Technologist is encountering this type of matter so it is very helpful especially when predicting the outcomes of chemical reaction.

Ma. Roselle Angela S. De Leon - BSMT 1 on August 19, 2018:

Stoichiometry deals with the numerical relationships of elements and compounds and the mathematical proportions of reactants and products in chemical transformations. This helps us to know how many moles does and elements or compound have. This includes computations that will help you to find the answer easier. Knowing how to get the number of moles will be an andvantage for us because we will be working in labaratories and we will be facing a lot of chemicals that we will be using.

anjelacastro2 on August 19, 2018:

CASTRO, ANJELA V. (BSMT-1) - The word “stoichiometry” is derived from two Greek words “stoichion” meaning element and “metry” meaning measure. This topic helps us to know how to deal with the numerical relationships of elements and compounds. This also gives us the advantage of knowing how to properly balance chemicals which is needed for our future job.

Allen Tuazon BSMT on August 19, 2018:

Tuazon, Allen Patrick F. (BSMT-1) - Stoichiometry helps us to know what moles are and how we can use it for our studies in the way we can calculate some equation related to moles easily and we can percentage each element to know and limit that element.

Pinky Miranda on August 19, 2018:

Miranda, Ma. Pinky Ramei V. (BSMT1) - Studying Stoichiometry will help us to know how many moles does an element or compound contains because stoichiometry deals with the numerical relationships of elements and compounds. It will help you to understand the relationship of the mass of the elements and this lesson will help you to solve problems correctly by using Avogadro's number and their percentage composition.

Chloe Bundalian on August 19, 2018:

Budalian, Chloe Jane L. BSMT1- Stoichiometry help us, Med students, to make our work easier to have a direct results in our future career.

Darah Arthria Cristobal from San Ildefonso, Bulacan on August 17, 2018:

CRISTOBAL, DARAH ARTHRIA DC. BSMT-1 As a Medtech student, stoichiometry hepls us to know the number of moles and molecules of element or compound. And by this slides, we learned what are the differences between Molar mass and Molecular mass.

Krichelle kae Calderon Enriquez from San Miguel, Bulacan, Philippines on August 16, 2018:

Learning stoichiometry helps us med tech student to gain more knowledge. This will help us to go to another level of learning. Not only us can gain knowledge but also others who wanted to learn more.

KristineCassandra on August 16, 2018:

Jota, Kristine Cassandra B.

BSMT 1

Stoichiometry is the study of the quantitative aspects of chemical reactions. In this topic moles, molecular mass, molar mass, avogadro's number and percentage composition were also mentioned and discussed. This will help us to gain more knowledge about this topic.

ivoryshanesalonga on February 06, 2018:

ivory shane salonga

bstm 4-1

stochiometry is the calculation of relative quantities of reactants and products in chemical reactions. the relevancd of this topic in my course is like this. in tourism we count and calculate distance of one place to another by counting hours. and in stochiometry we calculate relative quantities.

Jerielen Mangahas on February 05, 2018:

JERIE LEN MANGAHAS

BSTM 4 (FRIDAY-TUTORIAL)

Stoichiometry expresses the quantitative relationship between reactants and products in a chemical equation. Stoichiometric coefficients in a balanced equation indicate molar ratios in that reaction. Stoichiometry allows us to predict certain values, such as the percent yield of a product or the molar mass of a gas..

Tedyliza Ramos on January 18, 2018:

RAMOS, TEDYLIZA ROSE C.

BSTM 4

(TUTORIAL-FRIDAY)

Stoichiometry measures these quantitative relationships, and is used to determine the amount of products and reactants that are produced or needed in a given reaction

Teddy Gullem on September 21, 2017:

Stoichiometry involves using relations between reactants and/or products in a chemical reaction to determine desired quantitative data. Stoichiometry is part of chemistry that studies amounts of substances that are involved in reactions.

Camille San Mateo on September 21, 2017:

SAN MATEO, CAMILLE C.

BSN-1

The study of quatitative aspects of chemical reactions that deals with the numerous relation. It is important because it is the heart of the production of many things that can be use in our everyday lives. Those things are chemically produced through chemical reactions.

Bianca Bernardo on September 06, 2017:

Stoichiometry is the quantitative qualities of a chemical reaction. It is used in getting the amount of molecules in a compound or an element, the total masses in a reaction, and even the percentage that each element plays in a reaction. It is essential for us to know the basics in stoichiometry as we should know how much of a reactant will affect a reaction and how much we should only use. This also goes for giving medicines to patients as all chemicals have different reactions to different bodies and knowing how to solve for the percentage or amount of atoms in a reaction will give us a guideline on how much medicine a patient is only supposed to take.

Christian Paul V. Ogorida BSCE on September 05, 2017:

Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. This means that if the amounts of the separate reactants are known, then the amount of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of product can be empirically determined, then the amount of the other reactants can also be calculated.

RUSSELL BERNARDINO on August 28, 2017:

Knowing stoichiometry can help us find out the composition of molecules and general proportions of how to combine things to get them to react completely.

Stoichiometry is exactly that. It is the quantitative relation between the number of moles (and therefore mass) of various products and reactants in a chemical reaction.

Having the right proportions of things gets pretty important when you don't have a whole lot of reactants to waste (cost reduction), or when you're in the field of pharmacy (preventing overdose and death).

Additionally, the skills you get from learning how to do stoichiometry problems are probably THE most important thing to take away from a chemistry class. Dimensional analysis (aka. unit cancellation) will help you in every single science class you ever take - especially physics - and can often help you get a correct answer on a problem you don't completely understand as long as you know your answers has the correct units.

Gil Calderon on August 27, 2017:

What stoichiometry is, it allows us to do is to start comparing the quantities of reactants and product together. So that when we have certain amount of reactant we can figure out how product we can produced, or if we know how much product is produced we can turn how much reactant must have been used up in order to produced that product. However, what we relies on is to understand not only the numbers in a balance equation but also the masses of those component. What can we do is to count out and take quantity of a large number them so that we can mass say an electronic balance a large number of these molecules or compound in an atom.

Dave Joshua Villangca on August 24, 2017:

VILLANGCA, DAVE JOSHUA B.

BSN-I

Stoichiometry also means chemical computations. Studying this chapter is quite difficult but knowing the mole concepts, how to balance an equation and understanding the molecular mass of elements and compounds makes it easier for us to solve stoichiometric problems. When it comes to relevance of this topic to my course, which is nursing, is that we can understand more the compositions, numbers of molecules and percentage composition of the medications that we will be giving to our future clients. Because of that, we will be able to prevent errors that may cause the patient to suffer more or worst, death.

TORIBIO, PAULINE LOUISE A. on August 24, 2017:

TORIBIO, PAULINE LOUISE A.

BSN-I

Stoichiometry is the process of calculating the number of reactants and products of a reaction. This chapter of chemistry may be hard but useful for a nursing student like me. As of what I have read, I can relate this to medical dispensing. For example, some medications are given based on weight and age. We have to re-calculate the weight or age with the medicine that a patient will take. A wrong calculation may lead to overdose. That is why this chapter is important for us.

Denise arceo on February 25, 2017:

Denise R. Arceo

BAC- II

Stoichiometry deals with the computation in chemistry- it talks about chemical computations based on molar masses and ratios. Balancing out the chemicals and reactants using equations and computations.

In communication, we can use the value of balancing our time to be productive and release our creative juices in our respective fields and to balance our time efficiently.

Aldrinsntg on February 25, 2017:

Aldrin L Santiago BSPSY II

stoichiometry deals with chemical calculations, it's hard to understand it but as we go along in the lesson we can understand how to calculate the molar mass molecular mass and the percentage calculations of an element. It talks about the quantitative measurement. I can use these calculations in my future field.

Aldrin L Santiago on February 25, 2017:

Aldrin L Santiago BSPSY II

stoichiometry is hard to understand, but as we get along the lesson proper, we can say that it is important in our daily lives. It talks about the chemical calculations- how to compute the molar mass, molecular mass, and the percentage composition of an element. I can use this in my future field for me to handle different patients. How to hold my temper and calm myself.

jerson maniego BSHM-4 on February 25, 2017:

Stoichiometry

Stoichiometry is simply the math behind chemistry. Given enough information, one can use stoichiometry to calculate masses, moles, and percents within a chemical equation.

Luisito Dimagiba on February 25, 2017:

BSHM

Is an expression which states the number and type of atoms present in a molecule of a substance. The type of atom is given using element symbols. The number of atoms is indicated by a subscript following the element symbol.

Rafael Adriano on February 24, 2017:

Stoichiometry measures these quantitative relationships, and is used to determine the amount of products/reactants that are produced/needed in a given reaction. Describing the quantitative relationships among substances as they participate in chemical reactions is known as reaction stoichiometry. As an ABCOM student we need to be accurate for everything from simplex up to the most complex and doing it with proper information dissemination.

Jahna Carmella on February 24, 2017:

Jahna Carmella B. Galvez

BEED-II (Inorganic Chemistry/ TF/ 12:30-2:00)

Stoichiometry is important in production of a lot of things like what we see in our daily life. Soap, medicines, chemicals, gasoline, and also chocolate bars are just a few examples we use that are produced through chemical reactions.

Mary Grace Gonzales on February 24, 2017:

BU BSTM 4 Sci 202 T-F 7:30-12:00

In a chemical reaction, matter can neither be created nor destroyed, so the products that come out of a reaction must equal the reactants that go into a reaction. Stoichiometry is the measure of the elements within a reaction.[1] It involves calculations that take into account the masses of reactants and products in a given chemical reaction. Stoichiometry is one half math, one half chemistry, and revolves around the one simple principle above - the principle that matter is never lost or gained during a reaction. The first step in solving any chemistry problem is to balance the equation.

mariseperez08 on February 24, 2017:

Perez, Nina Marise V.

BEED- II (TF/ 12:30-2:00/ CAS 105)

Stoichiometry means "element measurement" in Greek and is also known as Mass Relations. The principles of stoichiometry are based on the Law of Conversation of Mass, the Law of Multiple Proportions, and the Law of Constant Composition. In order to satisfy all three laws, every chemical reaction and corresponding equation needs to have a set molar ratio for its reactants and products that explains how it proceeds to completion every time. Once determined, the molar ratio for an equation does not change as long as the equation itself is untouched and no other chemicals are added to the reaction.

Because the calculations in stoichiometry are based on molar ratios, the molar masses of the products can be used to determine theoretical yields and limiting reagents. Stoichiometry can also help determine the concentrations of solutions that were used, provided that enough variables are accounted for. A proper stoichiometric molar ratio functions forwards and backwards so that calculating values for the reactants can be performed if the corresponding values for the products are known.

Stoichiometry is important because it explains the relationships of reactants and products in chemical reactions. Without stoichiometry, it would be impossible to determine how much of a certain chemical is needed to yield a result or what molar amounts of each reactant and product are present in a completed reaction.

Stoichiometry is important because it explains the relationships of reactants and products in chemical reactions. Without stoichiometry, it would be impossible to determine how much of a certain chemical is needed to yield a result or what molar amounts of each reactant and product are present in a completed reaction.

frances birco on February 24, 2017:

Frances Birco

BAC-II

Stoichiometry is the process of calculating the relative quantities of reactants and products in chemical reactions. In being a field reporter in the future, we should verify and simplify the information for the audience to easily understand the news and not having so much time reporting a news to avoid confussion and misunderstanding.

Elize Bantang 14 on February 24, 2017:

Eliza B. Merle BEEd-ll

Stoichiometry is the section of chemistry that involves using relationships between reactants and products in a chemical reaction to determine desired quantitative data. In Greek, stoikhein means element and metron means measure, so Stoichiometry literally translated means the measure of elements. In chemical calculations it is necessary to consider quantities of substances in terms of the number of atoms, ions or molecules present. The unit devised by chemists in expressing these numbers of atoms, ions or molecules is called the mole. Mole is the unit of measurement used in chemistry in expressing amounts of a chemical substance. The molar mass is the sum of the masses of the atoms present in one mole of a substance, which can be an element or a compound. It can be expressed as a unit of mass per mole like grams/mol. Kg/mol. Empirical formula is a chemical formula denoting the constituent elements of a substance and relative number of atoms of each. It gives the simplest ratio of the number of the atoms. Stoichiometry is very useful in my course because in the future I am the assessor of my student's learning by computing their grades and also measuring their attitudes and characters inside the classroom.

JosephineLopez04 on February 23, 2017:

Lopez, Josephine V.

BEEd-II (BSC206B) (TF/ 12:30-2:00/ CS 105)

The term stoichiometry was first used by Jeremias Benjamin Richter in 1792 when the first volume of Richter's Stoichiometry or the Art of Measuring the Chemical Elements was published. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. This means that if the amounts of the separate reactants are known, then the amount of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of product can be empirically determined, then the amount of the other reactants can also be calculated.

Amira Ismail on February 23, 2017:

Amira Ismail

GENERAL CHEMISTRY

BAC-II

he word stoichiometry derives from two Greek words: stoicheion (meaning "element") and metron (meaning "measure"). Stoichiometry deals with calculations about the masses (sometimes volumes) of reactants and products involved in a chemical reaction. It is a very mathematical part of chemistry, so be prepared for lots of calculator use.

Maryn Pineda on February 23, 2017:

MARY NOELLE PINEDA BAC-II GENERAL CHEMISTRY TF 7:30-12:00 We have learned from reading the slides about the balancing equations and enabling us to solve stoichiometric problems involving mass relations of reactants and products of chemical reactions. We have learned about the mole concept, molar mass, about the Avogadro's number, the percentage composition, the empirical formulas and molecular formulas for of course, solve numerical problems. This part of the lesson is necessary to an AB Communication student for information dissemination, determining molar and molecular masses, calculate percentage composition of a compound, the empirical and molecular formulas.

Nik Miranda on February 22, 2017:

Miranda, Nixieline

BAC II

Using a balanced chemical equation to calculate amounts of reactants and products is called stoichiometry. It is a super technical-sounding word that simply means using ratios from the balanced equation. In this article, we will discuss how to use mole ratios to calculate the amount of reactants needed for a reaction.

Jannilene Tubon BAC II on February 22, 2017:

Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. This means that if the amounts of the separate reactants are known, then the amount of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of product can be empirically determined, then the amount of the other reactants can also be calculated.

AZ08 on February 21, 2017:

Eimeren Grace DC. Soriaga (Bs-PsyII)

For me Stoichiometry is important because it allows us to predict how much of reactant is consumed in a chemical reaction, or how much unwanted product is generated. This is especially important in medicine, because we would want the amount of toxic side products formed from the biochemical processes acting on the consumed medicine in our body to be minimal.

Maria Luz Mendoza on February 20, 2017:

Ma. Luz C. Mendoza BEED II

Stoichiometry means "element measurement" in Greek and is also known as Mass Relations. The principles of stoichiometry are based on the Law of Conversation of Mass, the Law of Multiple Proportions, and the Law of Constant Composition. In order to satisfy all three laws, every chemical reaction and corresponding equation needs to have a set molar ratio for its reactants and products that explains how it proceeds to completion every time. Once determined, the molar ratio for an equation does not change as long as the equation itself is untouched and no other chemicals are added to the reaction. Because the calculations in stoichiometry are based on molar ratios, the molar masses of the products can be used to determine theoretical yields and limiting reagents. Stoichiometry can also help determine the concentrations of solutions that were used, provided that enough variables are accounted for. A proper stoichiometric molar ratio functions forwards and backwards so that calculating values for the reactants can be performed if the corresponding values for the products are known.

Zipagan on February 05, 2017:

Dhaina Marie B. Zipagan (BAC-II)

Stoichiometry involves quantitative relationships in achemical reaction. Stoichiometric factors also called mole ratios, are based on the coefficients in the balanced equation and are used to relate moles of one reactant or product to another. The subject of stoichiometry involves quantitative calculations based on chemical formulas and chemical equation: Molecular masses and formula masses are the masses, expressed in atomic mass units (u), of individual molecules and formula units. They are calculated from the masses of the atoms represented in the molecular or empirical formulas, respectively. Molecular mass applies only to molecular compounds; formula mass is appropriate for ionic compounds; The Mole and Avogadro’s Number-A mole (mol) is an amount of substance containing a number of elementary entities (atoms, molecules, formula units, etc.) equal to the number of atoms in exactly 12 g of carbon-12; The Mole and Molar Mass-The mass, in grams, of one mole of substance is called the molar mass; it is numerically equal to an atomic, molecular, or formula mass but carries the unit g/mol. Conversions between the number of moles and the number of grams of a substance require molar mass as a conversion factor. Calculations involving volume, density, and numbers of atoms or molecules can also be used to determine molar quantities.

Apart from the regular and necessary use of stoichiometry in just about every single industrial application which uses chemical reactions in the world.... here are a couple everyday household examples;-

Say you have a cookie recipe that makes a dozen cookies. The "chemical" equation for this might look something like this;-4 cups flour + 2 eggs + 200g butter + 1 cup sugar = 12 cookies.

But you only have 1 egg. So, how much of each of the other ingredients do you need and how many cookies will the new recipe make?Well, if you divided each of the ingredients by two, the new equation would be;2 cups flour + 1 eggs + 100g butter + 1/2 cup sugar = 6 cookies.

Patricia Ann T. Cruz BSTM lll on February 04, 2017:

Stoiciometry involves quantitative relationship in a chemical reaction. Stoiciometry also called mole rations are based on the coefficients in the balance equation and are use to relate moles of one reactant or product to another. And almost all stoiciometry problems can be solved in just four simple steps balance the equation, convert units of a given substance moles, using the mole ratio, calculate the moles substance yielded by the reaction

Karen Mañalac. BAC IV on February 02, 2017:

Stoichiometry measures these quantitative relationships, and is used to determine the amount of products/reactants that are produced/needed in a given reaction. Describing the quantitative relationships among substances as they participate in chemical reactions is known as reaction stoichiometry.

Stoichiometry is important because it explains the relationships of reactants and products in chemical reactions. Without stoichiometry, it would be impossible to determine how much of a certain chemical is needed to yield a result or what molar amounts of each reactant and product are present in a completed reaction.

Cristina Perez on January 30, 2017:

Perez, Ma. Cristina M.

BEEd-II (BSC206B) (TF/ 12:30-2:00/ CS 105)

Stoichiometry is at the heart of the production of many things you use in your daily life. Soap, tires, fertilizer, gasoline, deodorant, and chocolate bars are just a few commodities you use that are chemically engineered, or produced through chemical reactions. Chemically engineered commodities all rely on stoichiometry for their production.

But what is stoichiometry? Stoichiometry is the calculation of quantities in chemical equations. Given a chemical reaction, stoichiometry tells us what quantity of each reactant we need in order to get enough of our desired product. Because of its real-life applications in chemical engineering as well as research, stoichiometry is one of the most important and fundamental topics in chemistry.

Maniella de Leon on January 30, 2017:

De Leon, Maniella Assumpta M.

BEEd-II (BSC206B) (TF/ 12:30-2:00/ CS 105)

In chemistry it is very important to understand the relationship between reactants and products in a reaction. Stoichiometry is exactly that. It is the quantitative relation between the number of moles (and therefore mass) of various products and reactants in a chemical reaction. Reaction stoichiometry allows us to determine the amount of substance that is consumed or produced by a reaction. The following video considers the first part of this: how much of a reactant is consumed in a chemical reaction. Product formation is discussed elsewhere. Knowing stoichiometry can help you find out the composition of molecules and general proportions of how to combine things to get them to react completely.

Carmela Perez on January 30, 2017:

Perez, Ma. Carmela M.

BEED- II (TF/ 12:30-2:00/ CAS 105)

Stoichiometry is the accounting, or math, behind chemistry. Given enough information, one can use stoichiometry to calculate masses, moles, and percents within a chemical equation. Stoichiometry is a section of chemistry that involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data. In Greek, stoikhein means element and metron means measure, so stoichiometry literally translated means the measure of elements. In order to use stoichiometry to run calculations about chemical reactions, it is important to first understand the relationships that exist between products and reactants and why they exist, which require understanding how to balanced reactions. As a future teacher, stoichiometry is somewhat relevant to our course because it deals with numerical figures and computations wherein in assessing the learners we need to know how to compute properly their grades and make it reasonable, balanced, and precisely.

Jucel Salvador on January 30, 2017:

BEEd-II (TF/12:30-2:00/CS 105)

The branch of chemistry which deals with the numerical relationships of elements and compounds and the mathematical proportions of reactants and products in chemical transformations is known as stoichiometry. This allows us to make predictions about the outcomes of chemical reactions. We can predict the mass of a product or the volume of a gas. Without the help of stoichiometry, it would be difficult for the students to determine how much chemicals or molar ammounts are needed to complete a reaction because the calculations in stoichiometry are based on molar ratios. As a student, stoichiometry is quite difficult to learn yet challenging. This gives us the ability to learn different chemicals and formulas to calculate.

Nikki Villaroman on January 27, 2017:

Villaroman Nikki D.C. Beed III

T/F BSC206b cas 105 12:30-2:00

Stoichiometry measures these quantitative relationships, and is used to determine the amount of products/reactants that are produced/needed in a given reaction. Describing the quantitative relationships among substances as they participate in chemical reactions. As a future educator i should be able to give learners grade measured to their performance and be able to explain of how they were able to acquire that certain grade.

Maricar Ramos on January 23, 2017:

Maricar Ramos BspsyII

Stoichiometry in chemistry, the study of the quantitative relationships between the weights (volumes) of reacting substances. Stoichiometry includes the derivation of chemical formulas and chemical equations, and its principles are used in the calculations of chemical analysis. The major postulates of stoichiometry are derived from Avo- gadro’s law, Gay-Lussac’s law of combining volumes, the law of multiple proportions, the law of definite proportions, the principle of the conservation of mass, and the law of equivalent proportions. The rules of stoichiometry govern all calculations related to chemical equations. Stoichiometric calculations are widely used in chemical engineering and metallurgy.

ChristianAnthonyRValino BSPsy II (7:30-12:00 T\F) on January 22, 2017:

Stoichiometry is at the heart of the production of many things we use in our daily life. Soap, tires, fertilizer, gasoline, deodorant, and chocolate bars are just a few commodities you use that are chemically engineered, or produced through chemical reactions. Chemically engineered commodities all rely on stoichiometry for their production. It is know as a branch of chemistry, which deals with the numerical relationships of elements and compounds and the mathematical proportions of reactants and products in chemical transformations.

Chella P. Maniquiz BSTM TF-7:30-12:00 on January 20, 2017:

Stoichiometry is important because it explains the relationships of reactants and products in chemical reactions. Without stoichiometry, it would be impossible to determine how much of a certain chemical is needed to yield a result or what molar amounts of each reactant and product are present in a completed reaction.

It is relevant in our course, especially in baking because we have to be certain in the amount of ingridients that we are going to mix.

Jerson G Maniego BSHM-4 (7:30-12:00 T\F) on January 09, 2017:

Stoichiometry is the study of the quantitative relationships or ratios between two or more substances undergoing a physical change or chemical change (chemical reaction). The word derives from the Greek words: stoicheion (meaning "element") and metron (meaning "to measure"). Most often, stoichiometry calculations deal with the mass or volumes of products and reactants.

Vivianjane Mempin on January 08, 2017:

Vivian Jane M. Mempin

BAC-II

Gen.Chemistry

TF/7:30-12:00/CS301

Stoichiometry deals with the calculation of the relative quantities of reactants and products in chemical transformations. This is necessary when it comes to laboratory experiments to produce a desired chemical reaction. Why or How? Because knowing how to balance equations, knowing the appropiate proportion or percentage of elements and compounds in a given substance, knowing the simple and exact ratio of number of atoms in a mole of a given compound, will lead you the desired result of your experiment. Failure to do so may result to lab accidents and wrong solutions.

In Communication, we have to balance out every information we receive from various sources. We have to know what percentage of it are true and what portion of it are lies. We also have to make sure that every composition of our news report is equally proportioned so that we could give our audience or listeners a good and accurate news report. Having done it may guarantee high ratings for our network.

Shara Mae T. Rivera BSHM 4-1 SCI 202 (TF 7:30-12:00) on January 07, 2017:

In chemistry, it is often important to know how efficient a reaction is. This is because when a reaction is carried out, the reactants may not always be present in the proportions written in the balanced equation. As a result, some of the reactants will be used, and some will be left over when the reaction is completed.

PatrickTan33BUHM on March 18, 2015:

Patricktan33BUHM

stoichiometry is Help in our field HM, because it can help us to know the kinds of chemicals that we will be using in cleaning. We can know of the chemicals that we are using are safe especially to our customer. As an HM student, stoichiometry really helps us a lot in our field. This deals with the interaction of chemicals to each other that we are dealing with in the future. this is a token for dealing with our future guests. Telling things to them that is accurate is thwir pleasure. This will be very helpful in pur field, it will let us know the kinds of chemical related in to our course.

Jole Ymenel Tila from Pulilan, Bulacan on March 09, 2015:

Tila Jole Ymenel F. BUHM

The quantitative relationship among reactants and products is called stoichiometry. Stoichiometry is very important in chemical equations because it tells you the relationship between substances in the same chemical equation. A balanced chemical equation is not just a qualitative description of a reaction, it is also quantitative. It tells us not just what the reactants and products are, but also the relative amounts of reactants and products that are involved in the reaction. The coefficients in the balanced equation tell us the relative number of formula units for each compound that participate in or are produced by the reaction.

Monic dela Cruz Sarmiento from San Miguel, Bulacan on March 08, 2015:

31Sarmiento, MDC BUHM

As we all know, Stoichiometry is all about measuring of elements. In our field, Hospitality Management, Stoichiometry is very much useful especially in Housekeeping Department and Food and Beverage Department. In cleaning. we uses different chemicals wherein we must use an exact amount for its good reaction. In preparing foods, we must also know to use right amount of ingredients specifically those additives that may harm to our costumers. Having knowledge about Stoichiometry really help our job easier and better.

Paulo Tomas on March 07, 2015:

TOMAS JP BUHM

Stoichiometry is the art of figuring how much stuff you'll make in a chemical reaction from the amount of each reagant you start with especially important in medicine, because we would want the amount of toxic side products formed from the biochemical processes.

Fatima Cruz Castro on March 05, 2015:

7 CASTRO F C BUTM 2014

Stochiomestry is important in our field, and it is a part of chemistry and they having a relationship of moles to atomic weights, this matter is also interesting but we need to give time to understand this and i think we need this in our working career.

kennethcorpuz on March 05, 2015:

30 corpuz kenneth B. TM

chemical calculation is contribute of calculate molecular and stoichiometry is a learn and about weight and atomic weight and control of experimental and use of laboratory apparatuses.

Rad Mesina from Calumpit, Bulacan on March 05, 2015:

23 MESINA, DJ BUHM

Stoichiometry is important in us hospitality management students. and it is also important to know how to balance the chemical that you apply in our food.

Clarenz Maximo on March 05, 2015:

21 MAXIMO, CR BUTM

Stoichiometry is the calculation of quantitative (measurable) relationships of the reactants and products in chemical reaction.

Phoebe Sp on March 05, 2015:

Stoichiometry is a branch of chemistry where we can determine the percentage composition of a compound. Stoichiometry is very essential because it helps us know the molecular and empirical formulas of compounds. It is important because without it, we wouldn't be able to know and determine the moles of a chemical formula.

SAN PEDRO, PM BUTM 35

jairafulgencio on March 05, 2015:

FULGENCIO JM BUTM 2014

Stoichiometry is the part of chemistry that studies amounts of substances that are involved in reactions. You might be looking at the amounts of substances before the reaction.

Rollyne Munsayac on March 05, 2015:

23 MUNSAYAC, RE BUTM 2014

Stoichiometry is the part of chemistry that studies amounts of substances that are involved in reactions. We should know the proper and right amount and mixture of ingredients.

yuriannesantos on March 05, 2015:

35, Santos YA BUTM 2014

Stoichiometry is the branch of chemistry, which deals with the numerical relationships of elements and compounds and the mathematical proportions of reactants and products in chemical transformations. We need to study stoichiometry because we are dealing with some chemicals and we need to know how to handle the appropriate amount in mixing and making some chemicals in a certain food.

28Quizon,CA BUTM on March 05, 2015:

Stoichiometry which deals with the numerical relationships of elements and compounds and the mathematical proportions of reactants and products in chemical transformations,

Zyrine Mae Taruc on March 05, 2015:

Taruc, Z.D BUTM 2014

Stoichiometry having a relationship of moles to atomic weights, the ratios that are arrived at by stoichiometry can be used to determine quantities by weight in a reaction described by a balance equation.

Jonna Mae Book on March 05, 2015:

BOOK, JM BUTM 2015

Stoichiometry rests upon the very basic laws that help to understand it better, the law of multiple proportions and the law of reciprocal proportions. In general, chemical reactions combine in definite ratios of chemicals. Since chemical reactions can neither create nor destroy matter, nor transmute one element into another, the amount of each element must be the same throughout the overall reaction. For example, the number of atoms of a given element X on the reactant side must equal the number of atoms of that element on the product side, whether or not all of those atoms are actually involved in a reaction.

Elli Rose Gabriel on March 05, 2015:

1 BALELA, E.G BUTM 2014

In my field as a tourism student, knowing stoichiometry can help you find out the composition of molecules and general proportions of how to combine things to get them react completely.

Melanie Samson on March 05, 2015:

SAMSON, MH BUTM2014-2015

Calculation of Chemicals is very important in my chosen field because Tourism Management as sister of Hospitality Management, we may be involved in restaurants as a cook and by this, this lesson will be a big help for us for the calculation of ingredients and other sources available for cooking.

27 PARUNGAO, GT BUTM on March 05, 2015:

Stoichiometry involves quantitative calculations based on chemical formulas and chemical equations. In this lesson you will learn all about conversion factors and how to use them. You will use them to solve general problems and then, to solve the stoichiometry problems.

Marife DG. Montejo on March 05, 2015:

Stoichiometry is really hard but when you started to understand it and do the correct steps you can solve the problems. Just also like in reality all you need to do is analyze your problems well and do things in the right way to solve it.

Capanas MJ BUHM on March 05, 2015:

Capanas MJ BUHM

The chemical bonding in our daily lives is that we have to learn how to be independent.

MarjorieLansanganBSHM on March 04, 2015:

Stoichiometry is a section of chemistry that involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data.stoichiometry we can help in Hospitality management to balance the chemical and food or alcohol.

Reniel Carillo on March 04, 2015:

stoichiometry we can help in Hospitality management to balance the chemical and food or alcohol.

Adrienne DelaCruz on March 04, 2015:

As a bshm student,stoichiometry It helps to balance the amount of chemical or ingredients we can mix food clearly.

Julien Villanueva on March 04, 2015:

Villanueva, Julien / BUHM 2014-2015

Stoichiometry is important because it allows us to predict how much of reactant is consumed in a chemical reaction, or how much unwanted product is generated. This is especially important in medicine, because we would want the amount of toxic side products formed from the biochemical processes acting on the consumed medicine in our body to be minimal.

john angelo ortega BSHM2 on March 04, 2015:

stoichiometry is very important component of chemistry, especially in our field as a bshm student, it was very useful when I start working as a chef, having a knowledge about this can help me to know the proper amount of ingredients i needed to make a specific food. also in cleaning a hotel being a housekeeper it can help me by knowing the balance amount of chemicals needed to clean a specific part of a hotel

Jan Carlo Buencamino from Banga 2nd Plaridel Bulacan on March 04, 2015:

Stoichiometry .

In Hospitality Management it helps us to know how many / how much of certain ingredients must be added

Patrisha Anne D.Vanguardia from San Ildefonso,Bulacan on March 04, 2015:

Stoichiometry helps us to balance equations.

as a Hospitality Management student it helps us to calculate the foods or dishes that we can make with our available amount of ingredients in the kitchen.

Glenric Samaniego on March 04, 2015:

It is very helpful for our course because it helps us know the amount to be added in a certain beverage or meal.

john andrew Cabrera on March 04, 2015:

Stoichiometry is in relevance on our chosen field because it is the calculation of quantities in chemical equations. it is important in field of Hospitality Management because it can hepl us to balance how many chemicals we can use and we can mix beverage properly by computing it.

jessa pantan on March 04, 2015:

Stoichiometry is important in field of Hospitality Management because it can hepl us to balance how many chemicals we can use and we can mix beverage properly by computing it. There are so many way that Stoichiometry can help us.