Introduction to Stoichiometry

Reaction Stoichiometry

The relationships between reactants and

products in a chemical reaction are

studied through reaction stoichiometry.

Reaction Stoichiometry and

Chemical Equations All reaction stoichiometry begins with a

balanced chemical equation and the law of

conservation of matter.

Recall that balanced chemical equations

give us a relative number of moles of

reactants and products

Reaction Stoichiometry Problem

Types Mole-Mole: Given and unknown quantities

are amounts measured in moles

– Mol X Mol Y

Mass-Mole: Given is an amount measured

in moles. Unknown is a mass measured

in grams.

– Mol X Mass (g) Y

– Mass (g) X Mol Y

Reaction Stoichiometry

Problem Types Mass-Mass: Given and unknown quantities are measured in grams.

–Mass (g) X Mass (g) Y

Solving Reaction

Stoichiometry Problems To solve a stoichiometry problem you will

use mole ratio and Molar mass as the

conversion factors.

Molar mass is the conversion factor used

to relate one mole of a substance to its

mass in grams.

Molar mass is used to convert

g X mol X or

mol X g X

The mole ratio is a conversion factor used

to describe the relative amounts of two

different substances in a chemical

reaction. It is derived from the balanced

chemical equation.

Mole ratio is used to convert

mol X mol Y

Practice Problems Mole-Mole Ammonia, NH3, is widely used as a fertilizer and in may

household cleaners.

How many moles of ammonia (nitrogen trihydride) are

produced when 6 mol of hydrogen gas react with an

excess of nitrogen gas?

Practice Problems Mole-Mole Ammonia, NH3, is widely used as a fertilizer and in may household

cleaners. How many moles of ammonia are produced when 2 mol of

nitrogen gas react with an excess of hydrogen gas?

N2 + H2 NH3

Practice Mass-Mole When magnesium burns in air, it combines with oxygen

to form magnesium oxide. What mass in grams of

magnesium oxide is produced from 2.00 mol of

magnesium?

In a spacecraft, the carbon dioxide exhaled by astronauts can be

removed by its reaction with lithium hydroxide. Lithium carbonate

and water are produced during this reaction. How many moles of

Lithium hydroxide are required to react with 80.0 g of CO2, the

average amount exhaled by a person each day?

The decomposition of potassium chlorate yields

potassium chloride and oxygen gas. It is used as a

source of oxygen in the laboratory. How many moles of

potassium chlorate are needed to produce 32.0 g of

oxygen?

Practice The decomposition of potassium chlorate into potassium chloride and

oxygen is used as a source of oxygen in the laboratory. How many moles

of potassium chlorate are needed to produce 15 mol of oxygen?

KClO3 KCl + O2

What mass of glucose can be produced from a photosynthesis reaction that

occurs using 10 mol CO2?

CO2 + H2O C6H12O6 + O2 What mass of carbon dioxide, in grams, is needed to react with 40.0g of

water in the photosynthesis reaction?

CO2 + H2O C6H12O6 + O2 In a spacecraft, the carbon dioxide exhaled by astronauts can be removed

by its reaction with h hydroxide. How many grams of Lithium hydroxide are

required to react with 20.0 mol of CO2, the average amount exhaled by a

person each day?

CO2 + LiOH Li2CO3 + H2O

Mass-Mass

AgNO3 + BaCl2 AgCl + Ba(NO3)2

If 5.0 grams of silver (I) nitrate react, how

many grams of barium chloride will also

react?

Mass-Mass

AgNO3 + BaCl2 AgCl + Ba(NO3)2

– 5.0g AgNO3 = _____g BaCl2

– 5.0g AgNO3 = _____g AgCl

N2 + H2 NH3

– 50.0 g N2 = _____g NH3

– 100.0 g N2 = _____g H2

KClO3 KCl + O2

– 25.0 g KClO3 = _____g KCl

– 20.0g KClO3 = _____g O2