Explore BrainMass


Stoichiometry refers to the study of relative quantities of reactants and/or products within a defined chemical system. It focuses on the relationships among quantities of reactants and products usually forming ratios of positive integers due to the nature of the bonded atoms. For example, in the combustion of methane (CH4), exactly 1 mole of methane reacts with 2 moles of oxygen to form 1 mole of carbon dioxide and 2 moles of water:

CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l)

Considering the relative abundances of reactants and products is a specific branch of stoichiometry called ‘reaction stoichiometry.’ In the example above, reaction stoichiometry describes the 1:2:1:2 ratio of molecules CH4, O2, CO2 and H2O. These ratios can be used to determine values such as the percentage yield of products under different conditions, the presence of a limiting reagent, and even predict the behavior of certain elements under experimental conditions.

Thus, understanding the fundamentals of stoichiometry can help calculate the desired quantitative data regarding chemical reactions, as well as other value which do not pertain to chemical reactions, such as the examination of elements within compounds and the behavior of gases.

Categories within Stoichiometry

Reaction Stoichiometry

Postings: 46

Reaction Stoichiometry refers to the examination of the relative abundances of reactants and products in a chemical reaction within a defined system.

Composition Stoichiometry

Postings: 8

Composition Stoichiometry refers to the examination of the relative abundances of elements within chemical compounds.

Gas Stoichiometry

Postings: 16

Gas Stoichiometry refers to the examination of the relative proportions of reactants and products in a chemical reaction involving gases.

Stoichiometry of Combustion

Postings: 3

Stoichiometry of Combustion refers to the examination of the relative proportions of fuel and oxygen required to carry out a complete combustion reaction.

Law of Definite Proportions

Postings: 1

The Law of Definite Proportions states that a chemical compound always contains exactly the same proportion of elements by mass.

Law of Multiple Proportions

Postings: 1

The Law of Definite Proportions states that when two different elements combine to form more than one compound, the quantity of one element combined with a fixed amount of the other element, exhibits a simple whole number ratio.

Solutions, Precipitations, and Balancing Equations

1 - Presuming that these molecules are soluble, tell what ions are "produced" upon dissolving. Rb2SO4 NaC 2H3O 2 AlCl3 2 - Calculate the molarity of 13.2 g of NaOH dissolved in 250 ml of water 27 g of C6H 12O6 in 400 ml of water 3 - How many grams of BaCl2 would you need to make 200 ml of a 0.75 M solutio

Radiopharmaceutical Questions

The following questions involve radiochemistry. Concepts covered include radiopharmaceutical question: looking at radionucleotide accumulation in the brain and mammogram photons.

Freezing Point Depression of Water by Sucrose

We need to calculate the molar mass of sucrose from the freezing point depression of water using a MeasureNet temp probe to get the cooling curves of water and sucrose. We haven't covered "molality" yet, and I'm looking for a simple way to determine these values? I'm more than willing to do the work myself, I just need a push in

Determining the density of gasses

a) Determine the density of methane (CH4) in g/L at 28oC and 0.9 atm. Round to two decimal places, do not include units. b) Sodium metal reacts with water according to the following equation: 2Na(s) + 2H2O(l) --> 2NaOH(aq) + H2(g) How many Liters of hydrogen gas will be produced if 29.9 g of solid sodium are completely r

Calculating the volume, temperature, and density of liquids and gasses

a) Which of the following is not a unit of pressure? atm torr mm Hg Pascal all of these are units of pressure b) What device is used to measure atmospheric pressure? c) What pressure (atm) is exerted by a column of ethanol 55.0 cm high? The density of ethanol is 0.789 g/cm3 and 9.8m/s2 as your gra

Stoichiometry worksheet

Question 1 What is the molar mass of propane (C3H8)? Use the average molar masses on the periodic table. Do not include units. Round to two decimal places. Question 2 What is the percent composition of carbon in sodium carbonate (Na2CO3)? Use the average molar masses on the periodic chart, do not include units, roun

Density of Chloroform

Please see attachment and provide work so it can be use as reference! Density 1- Calculate the density of chloroform using the data in the picture below. 2- A glass sample bottle weighs 24.225 g when empty. When filled with carbon tetrachloride, CCl4, it weighs 28.715. If the density of carbon tetrachloride is 1.5842 g/m

Properties of Solutions: Colligative Properties

Properties of Solutions 1. Anthraquinone contains only carbon, hydrogen and oxygen and has an empirical formula of C7H4O. The freezing point of camphor is lowered by 22.3oC when 1.32 g of antraquinone is dissolved in 11.4 g of camphor. Determine the molecular formula of anthraquinone. ( Kf for camphor is 40.0). 2. A solut

Calculations: Volume, Density, Mass, Efficiency, Conversions

1. Calculate the volume of 235.1 g of mercury (D=13.5g/cm3). Round to one decimal place, do not include units in your answer. 2. The empty cylinder has a mass of 45.8 g. A liquid is added and the mass of the liquid and the cylinder is 107.2. What is the density of the liquid in the cylinder? Round to one decimal place; do not

Measurement and Scientific Notation

1. In a density experiment, a student experimentally measures the following four values for the density of liquid ethanol: 0.772g/ml, 0.774g/ml, 0.785g/ml, and 0.775g/ml. The theoretical density of ethanol is 0.789 g/ml at 20ºC. a. Compute the average density of ethanol. b. Compute the % error for the average density (to 2 si

Naming Chemical Substances

1 - What is the name of Ni(CH3CO2)3? 2 - What is the name of Al(HCO3)3? 3 - What is the name of Sn3As2? 4 - What is the name of MnSO4? 5 - What is the name of Co(CN)3? 6 - What is the name of CuF2? 7 - What is the name of BrO2? 8 - What is the name of CCl4? 9 - The chemical substances in the first column of the ta

General Chemistry Problem Set

Please refer to the attached file for the questions. I would like to get answers for all the red highlighted questions. Part 1: The mole provides a convenient package where we can make a connection between the mass of a substance and the number (count) of that substance. This is a familiar concept if you have ever bought nai

de Broglie Wavelength of a Rifle Bullet

A certain rifle bullet has a mass of 8.13 g. Calculate the de Broglie wavelength of the bullet traveling at 1721 miles per hour. Physical constants are found below: Physical Constants Quantity Symbol Value speed of light in a vacuum c 2.99792458Ã-108 m/s (exact) Planck's con

Molar Solutions - NaOH

Please show steps and provide a short explanation. The formula weight of NaOH is 40.0. 1. How many grams of NaOH are needed to make 1M solution? 2. How many grams of NaOH are needed to make a 0.5M solution? 3. How many grams of NaOH are needed to make 0.25M solution? 4. How many grams of NaOH are needed to make 500m

Calculation Based on Purifying Groundwater

Perchloroethylene is an industrial solvent that can be used for metal degreasing. If 2000 L of perchloroethylene were accidentally leaked into the environment and entered the groundwater, how many tonnes of iron would be needed to purify the groundwater using an underground permeable wall? (perchloroethylene density = 1.623 g/mL

Volume of Cyclohexane Should be Used

After a label fell off a bottle containing a clear liquid which is believed to be benzene, a chemist measured the density of the liquid to verify its identity. A 25.0 ml portion of the liquid had a mass of 21.95g. A chemistry handbook lists the density of benzene at 15 degrees celcius 0.8787g/ml. Is the calculated density in agr

Weapons of Mass Destruction

I'd like to get some outside conversation on the following question. Why do you think the issue of Weapons of Mass Destruction is an important topic and how does it impacts on the global community?

Mass of Na2CS3 produced in the reaction.

For the reaction, given below, how many grams of Na2CS3 are produced in the reaction of 65 mL of liquid CS2 (d=1.26 g/mL) and 1.56 mol NaOH?3CS2 + 6NaOH -> 2Na2CS3 + Na2CO3 + 3H2O we can make calculations to determine the amount of reactant we need, or the amount of product we can expect to be produced in a chemical reaction.

The Freezing Point of a Solution of an Unknown Substance

Add 2g of the unknown solid #1 and 10 mL of water to the test tube. the constant temperature bath is still set to dry ice. Drag and drop the constant temperature bath onto the test tube containing the solution. Repeat the measurement of the freezing point with unknown solid #2 using a new clean test tube. As with solid #1 use

Molality, freezing point and boiling point of solutions: Example questions

What is the freezing point, boiling point, and molality of a solution with 150 grams of aluminum chloride dissolved in 350 mL of water? How much ethyl alcohol, C_2H_5OH is needed to dissolved 75 grams of naphthalene, C_10H_8 and produce a 0.1 molal solution? How many litres of water would be needed to dissolve 25 grams of

Chemical Reactions: Stoichiometry and Metals

1. Calculate the molar mass of the following compounds: a. sodium selenide b. Palladium (II) hydroxide 2. Calculate the number of grams in each of the following compounds: a. 4.0 moles of CaCl2(s) b. 0.467 moles of (NH4)CO3(s), baking powder 3. Calulate the number of moles in each of the following compounds: a. 150.0

What is the weight percentage of C in C6H12O6?

1. What is the weight percentage of C in C6H12O6? Use sig figs 2. What is the molar mass of TiCl4? 3. What is the molarity of a 1.30 L solution containing 6.00g of NaCN? Use sig figs 4. Write a balanced chemical equation for the combustion of octane, C8H18 5. 20.0g each of Fe2O3 and Al are mixed together and react according

Stoichiometry Example Problems

1. Calculate the emperical formula for a chemical compound which gives the following analysis 12.6 percent lithium 29.2 percent sulfur and 58.2 percent oxygen? 2. The action of bacteria on meat and fish produces a poisonous compound called cadaverine. It is 58.77 percent carbon, 13.81 percent hydrogen, 27.40 percent nitrogen.

Analysis of Hydrogen Peroxide Solutions

Molarity of KMnO4: .2 M Volume of H2O2: 10 mL Titration of KMnO4 and new H2O2 Trial 1(Rough) Trial 2(Fine) Trial 3(Fine) Initial volume 12.00mL 12.00mL 12.00mL Final volume 13.98mL 12.10mL 12.05mL Titration of KMnO4 and old H2O2 (Fine Ti

Tempurature Dependence of Salt Solubility. Calculations Help

I don’t understand how to make this graph...what is it supposed to look like? I’ve tried and just can’t make my computer work it...I also don’t understand what my experimental mass and official masses are supposed to be... please help! Data: List all measurements and include proper labels. Test tube Crystallizing Tempe