Chapters 7 Concept Review and Practice Problems

Chapter 7: Chemical Quantities

What is mole a measurement of ? What is another way of saying a mole? How many particles are there in a mole?

Determining formula mass, molecular mass, formula weight, molecular weight and molar mass

Conversions

gram to mole / mole to gram

atoms to mole / mole to atoms

gram to particles/particles to gram

            Calculate percent composition

            Determine empirical formula from masses, percentages or moles

            Determine molecular formula from molecular weight and empirical formula.

1. Identify elements and ions in the following substances and how many you have of each: HI, CO₂, BaCl₂, CaSO₄, (NH₄)₃PO₄

2. What is the molar mass of the compounds in question 1?

3. If you have 12 grams of CO₂, how many moles do you have? what about molecules?

4. What is the percent composition of each element in CaSO₄?

5. If you have 40 g of Ca and 70.8 g of Cl, what is the empirical formula?

6. What is the empirical formula for N₂O₆?

7. If the empirical formula for a compound is CH₂O, and the molecular mass is 90g, what is the molecular formula?

8. If you have 3.2 gal of water, how many cups is this? 1gal=4 qts and 1 qt=4 cups