Stoichiometry Problem Video

What is needed for every stoichiometry problem to be solved?

• The molar mass of all chemicals in the reaction.

• A balanced chemical equation.

• The mole ratio between all the chemicals in the reaction.

• The mass of all the chemicals in the reaction.

What are we solving for in the problem?

How many grams of Ca(OH)₂ are needed to react with 41.2 g of H₃PO₄?

Find: _______

Answer explanation

How many grams of Ca(OH)₂ are needed to react with 41.2 g of H₃PO₄?

Read the question to determine what is unknown that is being asked to be solved.

What is the given for the problem?

How many grams of Ca(OH)₂ are needed to react with 41.2 g of H₃PO₄?

Given: _____

Answer explanation

How many grams of Ca(OH)₂ are needed to react with 41.2 g of H₃PO₄?

Read the question to determine what is known that is being given as a starting point.

Place the steps in order of solving the problem.

1) ​ (a)  

2) ​ (b)  

3) ​ (c)   ​

​ 4) ​ (d)  

5) ​ (e)  

What is used to determine the mole ratio between two chemicals in a reaction?

• Mass of the reactant

• Molar mass

• Mass of the products

• Balanced chemical equation

Place the terms in the appropriate spot for using the mole ratio in this problem.

a

b

The molar mass of calcium hydroxide is _____ g/mol.

Why are the units of the molar mass and the mole ratio arranged the way they are in the setup?

How many grams of Ca(OH)₂ are needed to react with 41.2 g of H₃PO₄?

Answer explanation

The calculator answer is 46.7284 g Ca(OH)₂. However, the solution needs to be given to the correct significant digits.

How comfortable are you with stoichiometry problems?

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