1. An atom contains 17 electrons and 20 neutrons. Determine:
(a) the atomic number of the element
(b) the name of the element
(c) the number of protons
(d) the mass of the atom in a.m.u.
2. Name the following ionic compounds:
(a) NaCl
(b) KBr
(c) MgCl2
(d) NaOH
(e) Ca(OH)2 (f) LiCN
3. Write formulas for the following ionic compounds:
(a) barium nitrate
(b) aluminum sulfate
(c) iron(II) hydroxide
4. Name the following ionic compounds:
(a) NH4Br
(b) Cu2S
(c) CuS
(d) Ba(OH)2
5. State the formula for:
(a) chromium(III) phosphate
(b) nickel(II) nitrate
(c) sodium bromide
(d) magnesium oxide
6. Determine the percent composition of Mg3(PO4)2.
7. Calculate the percent composition of ethanol, C2H5OH.
8. A strip of electrolytically pure copper weighing 3.178 g is strongly heated in a stream of
oxygen until it is all converted to 3.978 g of the black oxide. What is the percent composition
of this oxide?
9. What weight of silver is present in 3.45 g Ag2S?
10. What is the empirical formula of a compound which contains 60.0% oxygen and 40.0%
sulfur by mass?
11. Derive the empirical formula of a hydrocarbon that on analysis gave the following percent
composition: C = 85.63%; H = 14.37%.
12. A compound gave on analysis the following percent composition: K = 26.57%; Cr = 35.36%;
O = 38.07%. Derive the empirical formula of the compound.
13. A 2.500-g sample of uranium was heated in the air. The resulting oxide weighed 2.949 g.
Determine the empirical formula of the oxide.
14. When 1.010 g of zinc is burned in air, 1.257 g of the oxide is produced. What is the empirical
formula of the oxide?
15. A compound has the following percent composition: C = 40.0%; H = 6.67%; O = 53.3%. Its
molecular weight is 60.0 a.m.u. Derive its molecular formula.
16. Determine the empirical formula and the molecular formula of a hydrocarbon which has a
molecular weight of 84 a.m.u. and which contains 85.7% carbon by mass.