Chemistry Unit 1 Ch4 Revision

CHAPTER 4 REVISION

1. How many moles of silver atoms are in 0.780 grams of silver?
a) 0.78 moles
b) 0.00723 moles
c) 84.2 moles
d) 0.522 moles
2. What is the molar mass of Mg(BrO4)2?
a) 312 g mol-1
b) 232 g mol-1
c) 168.2 g mol-1
d) 477 g mol-1
3. What mass of the compound FeWO4 contains 50.0 grams of tungsten (atomic symbol W, atomic number = 74)?
a) 30.0 g FeWO4
b) 304 g FeWO4
c) 82.6 g FeWO4
d) 188 g FeWO4
d) FeSO4
4. A compound contains 20.2% magnesium, 39.8% titanium, and 40.0% oxygen by mass. What is the empirical formula of this compound?
a) MgTiO
b) MgTi2O3
c) Mg2TiO4
d) MgTiO3
5. Which of the following DOES NOT contain 4.00 moles of oxygen atoms?
a) 2.00 moles of CO2
b) 128.0 g of SO2
c) 0.40 moles of P4O10
d) 4.00 moles of KClO3
6. A compound has an empirical formula of C2HBr. If the molar mass of the compound is 314.7 g/mol, what is the molecular formula of the compound?
a) C2HBr
b) C4H2Br2
c) C6H3Br3
d) C8H4Br4

7. What is the mass percent of copper in the mineral bornite, Cu4FeS4?
a) 44.4%
b) 58.0%
c) 14.5%
d) 72.4%
8. A 0.2420 sample of an unknown containing C, O, and H is burned completely. Analysis shows that 0.2265 grams of water are produced. How many grams of hydrogen were present in the 0.2420 grams of sample?
a) 0.0253 grams
b) 0.2265 grams
c) 0.0127 grams
d) 0.1522 grams
9. What is the mass of 0.220 moles of AgNO3?
a) 169.9 g
b) 0.415 g
c) 0.220 g
d) 37.4 g

Short Answers

Q1. Silver consists of two isotopes:

Relative Atomic Mass | 107 | 51.84 | Abundance | 109 | 48.16 |

Calculate the average relative atomic mass of silver.

Q2. Copper consists of two natural isotopes. The lightest isotope has a relative atomic mass of 62.9296 and the heavier isotope has a mass of 64.9278. If the average relative atomic mass of lithium is 63.546, find the abundance of each isotope.