Unit 7 Chemistry Review

1. How many atoms are in 2.2 moles of nitrogen? 1.32 atoms 3.65 x 10-24 atoms 1.32 x 1024 atoms 30.822 atoms

2. How many moles are in 53g of H2O? 2.94 moles 955.06 moles 18.02 moles 8.8 x 10-23 moles

3. How many atoms are in 72 grams of sulfur? 2.25 atoms 1.35 x 1024 atoms 3.8 x 10-21 atoms 72 atoms

4. What’s the mass of 1 x 1024 molecules of Br2? 132.68 g 3.77 x 1045 g 1.66 g 265.38 g

5. Which equation represents percent composition?

6. Which equation would be used to convert atoms to moles?

7. What’s the empirical formula of 54.09% Ca, 43.18% O, and 2.73% H? CaOH2 Ca(OH)2 CaOH CaH2O

8. What’s the empirical formula of 36.48% Na, 25.44% S, and 38.08% O? NaS2O Na2SO4 Na2SO3 NaSO4

9. Determine the molar mass of Copper (II) bromide. 223.35 g/mol 143.45 g/mol 207 g/mol 63.55 g/mol

10. What’s the molar mass of aluminum oxide? 101.96 g/mol 42.98 g/mol 112.94 g/mol 63.55 g/mol

11. What’s the percent composition of hydrogen in (NH4)2SO4? 8% 3.57% 6.11% 53.33%

12. What’s the percent composition of sodium in NaOH? 40 22.99% 33.33% 6.11% 57.47%

13. In the reaction between sodium & chlorine to form salt, what’s the mole ratio of sodium to salt? 1:2 2:2 2:1 2:4

14. In the decomposition reaction, hydrogen peroxide breaks down into water and oxygen. What’s the mole ratio of hydrogen peroxide to oxygen? 2:1 1:2 2:2 2:4