CHEM 1364

Test 2

Spring 1998

SHORT ANSWER: 2 points each. Fill in the blank with the most correct answer.

1. A(n) __________________ chemical equation shows all products and reactants with the correct stoichiometry.

2. The ____________________ yield for a reaction is a comparison of how much you get to how much you should get.

3. The ____________________ for a reaction is the reactant that is completely consumed during the reaction.

4. A(n) ____________________ is formed by mixing ions in solution that will form an insoluble compound.

5. The ____________________ equation is 'simplified' to show only the ions and molecules/precipitates in a chemical process.

6. An acid/base reaction is defined by the transfer of a(n) ____________________ from one species to another.

7. A(n) ____________________ acid will give up some, but not all, of it's donatable protons.

8. An acid/base ____________________ is a substance that will change color depending on the concentration of the hydrogen ion in solution.

9. A metal displacement reaction is a type of ____________________ reaction, since there is always an electron exchange occurring between the metal and the metallic ion.

10. The ____________________ Gas Law is a mathematical equation that includes Boyle's Law, Charles' Law, and the so-called 'Picnic Law.'

11. The ____________________ Gas Law takes into account all of the parameters from the equation in (11) while adding the parameter of the number of gas molecules.

12. ____________________ Law of Partial Pressure states that a gas in a mixture will exhibit the same 'partial' pressure as the same amount of gas under the same PVT conditions would exhibit if it were a pure gas.

13. The Kinetic Molecular Theory assumes that molecular volume = _____________.

14. The Kinetic Molecular Theory assumes that the ____________________ energy for a sample of gas will vary only with the temperature of the sample.

15. The ____________________ equation was developed to help describe real gases, and contains terms to compensate for the molecular volume and for the intermolecular forces.

PROBLEMS (Point totals are shown in parenthesis). Show your work and circle your answers where appropriate for full credit.

16. (15) For the following reactions; a) predict the products; b) write the balanced molecular equation; and c) define the type (precipitation, oxidation reduction, acid/base).

a) HNO3(aq) + Al(OH)3(s)

b) CuSO4(aq) + Zn(s)

c) AgNO3(aq) + HCl(aq)

17. (15) A chemist would like to make silver sulfide from silver nitrate and sodium sulfide. He finds that he has 35.8 g of Na2S, and 144.1 g of AgNO3. The reaction is:

2AgNO3 + Na2S 2NaNO3 + Ag2S

The percent yield for the reaction is 95.3%. Determine the limiting reactant, and calculate the actual yield for the process.

18. (10) Calculate the volume of a gas at STP that initially occupied a volume of 19.5 L at 25C and 750 torr.

19. (15) What is the molecular weight of a gas if 16.6 grams of the gas occupies a volume of 5.00 L at 30C and 100 kPa.

20. (15) Calculate the pressure of a sample of nitrogen (N2) if a 40.0 L tank contains 7.00 kg of N2 at 25C. Under these conditions nitrogen does not behave as an ideal gas. [The van der Walls constants are a=1.390 L2 atm mol-2; b=0.0391 L mol-1.

EXTRA CREDIT (10) Calculate the relative percent error if we assume that nitrogen is an ideal gas under the conditions in problem 20.

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