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Chemistry 117 - Principles of Chemistry
Fall, 2016
Problem Assignment 2
(due Friday, September 2, 2016)
Chapter 2, Oxtoby, Gillis, and Campion
Problems 19, 23, 26, 27, 35, 38, 42, 43, 45, 46, 48, 60, 63 (7th ed.)
Chapter 2, Oxtoby, Gillis, and Butler
Problems 7, 11, 14, 15, 23, 26, 30, 31, 33, 34, 36, 47, 50 (8th ed.)
and the handout on balancing equations
Additional Problems:
1. A 15.40-g sample of a finely-divided mixture of only Fe2S3 and FeS was reacted with
excess H2 at elevated temperatures. If the weight percent of Fe2S3 in this mixture is
57.4%, then calculate the total mass in grams of Fe that can be produced. Assume
the only other product of these reactions is H2S.
2. A mixture of elemental carbon and sulfur has a mass of 9.00 g. The complete
combustion of this mixture with excess O2 produces 23.00 g of a mixture of SO2 and
CO2. Calculate the weight percent of sulfur in the original mixture.
3. Upon hydrolysis, XF3, is converted to its corresponding oxide, compound, X2O3.
When a 4.50-g sample of XF3 is treated with excess water, 2.31 g of X2O3 is
obtained. Calculate the atomic weight and determine the identity of the element X.
4. Cyclist Floyd Landis was recently disqualified as the 2006 champion of the Tour de
France because of a higher than normal level of the male hormone testosterone
found during subsequent drug tests. Testosterone contains only C, H, and O. If the
complete combustion of 25.00 mg of testrosterone produced 72.48 mg of CO2 and
21.86 mg of H2O, determine its molecular formula.
5. Treatment of potassium iodide with nitric acid proceeds with the formation of
potassium nitrate, NO, elemental iodine, and water. Calculate the minimum
amounts in grams of I2 and NO, which may be prepared from the reaction of 20.5
grams of KI with excess nitric acid. Balance the chemical equation first.
____ KI + ____ HNO3 → ____ KNO3 + ____ I2 + ____ NO + ____ H2O
6. The 20.400-g sample of solid mixture of magnesium nitride, Mg3N2, and sodium
nitride, Na3N, was reacted with excess water. If a total of 5.281-g of gaseous NH3
was formed, then determine the weight percent of Mg3N2 in this sample.
Mg3N2(s)
Na3N(s)
+ 6 H2O(l) → 3 Mg(OH)2(aq)
+ 3 H2O(l)→
3 NaOH(aq)
+
+
2 NH3(g)
NH3(g)
7. The hydrolysis of calcium cyanamide, CaCN2, proceeds with the formation of
calcium carbonate and ammonia gas according to the unbalanced chemical reaction
shown below.
___ CaCN2(s)
+ ___ H2O(l)
→
___ CaCO3(s) + ___ NH3(g)
a. Calculate the mass of ammonia gas produced at STP when 60.0 g of CaCN2 is
treated with 45.0 g of H2O.
b. Calculate the mass of the excess reagent that remains once the reaction is
complete.
8. A 350.0-g sample of a mixture containing 30.5% K2CO3 and 69.5% KOH, by mass,
was reacted with excess HCl. Calculate the maximum number of grams of KCl and
the volume of CO2 gas produced at STP. Be sure to write separate balanced
equations for the reactions of HCl with K2CO3 and KOH.
9. A 1.959-sample of a compound composed of iron and carbon monoxide, Fex(CO)y,
was burned in pure oxygen to produce 0.799 g of Fe2O3 and 2.200 g of CO2. From
this information determine the empirical formula of this compound Fex(CO)y.