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Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
105
Stoichiometry
Stoichiometry
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
11
11.1 What is stoichiometry?
Stoichiometry is the study of quantitative relationships between
amounts of reactants used and products formed by a chemical reaction. Stoichiometry is based on the law of conservation of mass. The
law of conservation of mass states that matter is neither created nor
destroyed. Thus, in a chemical reaction, the mass of the reactants
equals the mass of the products. You can use stoichiometry to
answer questions about the amounts of reactants used or products
formed by reactions. For example, look at the balanced chemical
equation for the formation of table salt (NaCl).
2Na(s) ϩ Cl 2 (g) 0 2NaCl(s)
You could use stoichiometry to answer the following questions
about the chemical reaction.
• How much sodium is needed to produce a certain amount
of table salt?
• How much chlorine is needed to produce a certain amount
of table salt?
• Given a certain amount of sodium or chlorine, how much
table salt can be produced?
When you look at a balanced equation, there are two ways to interpret the coefficients. The coefficients tell you how many individual
particles are interacting in the chemical reaction. For example, from
the chemical equation above, you learn that two sodium atoms react
with one chlorine molecule to form two formula units of table salt.
You also learn that two moles of sodium react with one mole of
chlorine to form two moles of salt. What the coefficients do not tell
you directly is the masses of the reactants and the products in the
chemical reaction.
Example Problem 11-1
Interpreting Chemical Equations
Interpret the balanced chemical equation in terms of particles, moles,
and mass. Show that the law of conservation of mass is observed.
Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
105
Stoichiometry
Stoichiometry
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER
11
11.1 What is stoichiometry?
Stoichiometry is the study of quantitative relationships between
amounts of reactants used and products formed by a chemical reaction. Stoichiometry is based on the law of conservation of mass. The
law of conservation of mass states that matter is neither created nor
destroyed. Thus, in a chemical reaction, the mass of the reactants
equals the mass of the products. You can use stoichiometry to
answer questions about the amounts of reactants used or products
formed by reactions. For example, look at the balanced chemical
equation for the formation of table salt (NaCl).
2Na(s) ϩ Cl 2 (g) 0 2NaCl(s)
You could use stoichiometry to answer the following questions
about the chemical reaction.
• How much sodium is needed to produce a certain amount
of table salt?
• How much chlorine is needed to produce a certain amount
of table salt?
• Given a certain amount of sodium or chlorine, how much
table salt can be produced?
When you look at a balanced equation, there are two ways to interpret the coefficients. The coefficients tell you how many individual
particles are interacting in the chemical reaction. For example, from
the chemical equation above, you learn that two sodium atoms react
with one chlorine molecule to form two formula units of table salt.
You also learn that two moles of sodium react with one mole of
chlorine to form two moles of salt. What the coefficients do not tell
you directly is the masses of the reactants and the products in the
chemical reaction.
Example Problem 11-1
Interpreting Chemical Equations
Interpret the balanced chemical equation in terms of particles, moles,
and mass. Show that the law of conservation of mass is observed.