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Questions and Problems About Reactions in Aqueous Solutions


Questions and Problems About Reactions in Aqueous Solutions

1.      Classify these reactions according to the types discussed in the chapter:
(a) Cl2 + 2OH- → Cl- + ClO- + H2O
(b) Ca2+ + CO32- → CaCO3
(c) NH3 + H+ → NH4+
(d) 2CCl4 + CrO42- → 2COCl2 + CrO2Cl2 + 2Cl-
(e) Ca + F2 → CaF2
(f) 2Li + H2 → 2LiH
(g) Ba(NO3)2 + Na2SO4 → 2NaNO3 + BaSO4
(h) CuO + H2 → Cu + H2O
(i) Zn + 2HCl → ZnCl2 + H2
(j) 2FeCl2 + Cl2 → 2FeCl3
2.      Someone gave you a colorless liquid. Describe three chemical tests you would perform on the liquid to show that it is water.
3.      You are given two colorless solutions, one containing NaCl and the other sucrose (C12H22O11). Suggest a chemical and a physical test that would distinguish between these two solutions. (Physical test: Only the NaCl solution would conduct electricity. Chemical test: Add AgNO3 solution. Only the NaCl solution would give AgCl precipitate.)
4.      Chlorine (Cl2) is used to purify drinking water. Too much chlorine is harmful to humans. The excess chlorine is often removed by treatment with sulfur dioxide (SO2). Balance the following equation that represents this procedure:
Cl2 + SO2 + H2O → Cl- + SO42- + H+
5.      Before aluminum was obtained by electrolytic reduction from its ore (Al2O3), the metal was produced by chemical reduction of AlCl3. Which metals would you use to reduce Al3+ to Al? (Mg, Na, Ca, Ba, K, or Li).
6.      Oxygen (O2) and carbon dioxide (CO2) are colorless and odorless gases. Suggest two chemical tests that would enable you to distinguish between them.
7.      Based on oxidation number, explain why carbon monoxide (CO) is fl ammable but carbon dioxide (CO2) is not. (Oxidation number of C is +2 in CO and +4 (maximum) in CO2.)
8.      Which of these aqueous solutions would you expect to be the best conductor of electricity at 25°C? Explain your answer.
(a) 0.20 M NaCl
(b) 0.60 M CH3COOH
(c) 0.25 M HCl
(d) 0.20 M Mg(NO3)2
9.      A 5.00 x 102 mL sample of 2.00 M HCl solution is treated with 4.47 g of magnesium. Calculate the concentration of the acid solution after all the metal has reacted. Assume that the volume remains unchanged. (1.26 M)
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