Solving Stoichiometry Problems

Objectives:• 1. Name four major categories of

stoichiometry problems.• 2. Explain how to solve each type of

stoichiometry problems.

Mole-Mole Problems

Problem: How many moles of HCl are needed to react with 0.87 moles of Al?• Step 1: Balance The Equation

• Step 2: Set up the equation identifying the given and the want0.87 mol Al HCl

Al• Step 3: Calculate the new moles using the ratios of coefficients from the

balanced equation

0.87 mol Al 6 HCl = 2.6 mol HCl

2 Al

Mass-Mass Problems (MassgMol; MolgMol; MolgMass)

Problem: How many grams of Al can be created decomposing 9.8g of Al2O3?

• Step 1: Balance The Equation

• Step 2: Calculate the moles of the given (mol/g)

• Step 3: Calculate the moles of the new substance using the molar ratios

• Step 4: Calculate the new mass using the new moles

Solutions to Common Problems

particles

mass

volume

Mole given New mole using ratios

particles

mass

volume

/ 6.02x1023

/ molar mass

x 6.02x1023

/ 22.4L

x molar mass

x 22.4L

Mole to mole using the ratio of coefficients