1. 4.7 Calculating Chemical Change Stoichiometry Mole Ratio The key to these conversions is always the mole ratio, which is determined from the coefficients in the balanced equation. You may find it helpful to review two-wheel conversions introduced in chapter 3 and shown below.

2. 4.7 Calculating Chemical Change Stoichiometry Mass to Mass – Molar Mass Revisited In chapter 3, we learned to use the molar mass to convert the mass of a chemical substance to moles. We can now use the mole ratio to take such a conversion one step further. The mole ratio will allow us to convert the moles of one substance in a chemical reaction into moles of another substance. If we wish, we can then convert the moles of the new substance into its mass using an appropriate molar mass. This three-step process was introduced in chapter 3 and is shown again in Figure below.

3. 4.7 Calculating Chemical Change Stoichiometry Gases – Converting Volume to Volume