Exam 2 Chem 1100 Fall 2003 Dr. Byrd

MULTIPLE CHOICE. Choose the answer that best completes the statement or answers the question. Each correct answer is worth 2 points each.

1) Molarity is defined as

A) moles of solute per liter of solution.

B) moles of solute per liter of solvent.

C) moles of solvent per liter of solvent.

D) moles of solvent per liter of solution.

E) none of the above are correct.

2) What is the concentration of iron(III) chloride in a solution prepared by dissolving 10.0 g of FeCl₃ in enough water to make 275 mL of solution?

A) 2.24 x 10^-4 M

B) 4.46 x 10³ M

C) 0.224 M

D) 4.46 M

E) none of the above are correct.

3) What is the concentration of hydrochloric acid in the final solution when 65 mL of a 12 M hydrochloric acid solution is diluted with pure water to a total volume of 0.15 L?

A) 28 M

B) 5.2 x 10³ M

C) 5.2 M

D) 2.8 x 10^-2 M

E) none of the above are correct.

4) In an acid-base neutralization reaction 23.74 mL of 0.500 M potassium hydroxide reacts with 50.00 mL of sulfuric acid solution. What is the concentration of the H₂SO₄ solution?

A) 2.11 M

B) 0.119 M

C) 0.475 M

D) 0.237 M

E) none of the above are correct.

5) Which of the following statements is false concerning the formula of a compound?

A) The empirical formula is the simplest whole numbered ratio of atoms in a compound.

B) The molecular formula and empirical formula can be identical.

C) The molecular formula is the true ratio of atoms in a compound.

D) The number of atoms in a molecular formula is always greater than the number of atoms in an empirical formula.

E) All of them are true.

6) A hydrocarbon of unknown formula C_xH_y was submitted to combustion analysis with the following results. What is the empirical formula of the hydrocarbon?

A) C₂H B) C₄H₄ C) C₂H₄ D) CH₂ E) CH

7) HBr, HCl, HClO₄, KBr, and NaCl are all classified as

A) strong electrolytes.

B) weak electrolytes.

C) acids.

D) nonelectrolytes.

E) none of these are correct.

8) What is the molar concentration of sulfate ions in a 0.150 M sodium sulfate solution?

A) 0.150 M

B) 0.075 M

C) 0.450 M

D) 0.300 M

E) none of these are correct.

9) Which one of the following compounds is soluble in water?

A) CuS

B) Ag₃PO₄

C) Pb(NO₃)₂

D) ZnCO₃

E) All of them are soluble

10) The mixing of which pair of reactants will result in a precipitation reaction?

A) NH₄Br(aq) + NaI(aq)

B) Cu(NO₃)₂(aq) + Na₂CO₃(aq)

C) NaClO₄(aq) + (NH₄)₂S(aq)

D) K₂SO₄(aq) + Cu(NO₃)₂(aq)

E) none of these are correct.

11) Write a net ionic equation for the neutralization reaction of the weak acid, HCN(aq), with NaOH(aq).

A) HCN(aq) + OH^-(aq) Â CN^-(aq) + H₂O(l)

B) HCN(aq) + Na⁺(aq) + OH^-(aq) Â Na⁺(aq) + CN^-(aq) + H₂O(l)

C) H₃O⁺(aq) + OH^-(aq) Â 2H₂O(l)

D) HCN(aq) + NaOH(aq) Â NaCN(aq) + H₂O(l)

E) All of these are correct.

12) What is the oxidation number of the sulfur atom in H₂SO₄?

A) +4 B) 0 C) +2 D) -2 E) +6

13) Which species functions as the oxidizing agent in the following reduction-oxidation reaction:

5Fe²⁺(aq) + MnO₄^-(aq) + 8H₃O⁺(aq) Â Mn²⁺(aq) + 5Fe³⁺(aq) + 12H₂O)l)

A) Mn²⁺(aq)

B) MnO₄^-(aq)

C) Fe²⁺(aq)

D) H₃O⁺(aq)

E) Fe^3+(aq)

14) Using the following portion of the activity series for oxidation half reactions

Ca(s) Â Ca²⁺(aq) + 2e^-

Mg(s) Â Mg²⁺(aq) + 2e^-

Zn(s) Â Zn²⁺(aq) + 2e^-

Cu(s) Â Cu²⁺(aq) + 2e^-

determine which reaction will not occur.

A) Zn(s) with Mg²⁺(aq)

B) Zn(s) with Cu²⁺(aq)

C) Ca(s) with Cu²⁺(aq)

D) Ca(s) with Zn²⁺(aq)

E) All of these will occur.

Assume that an aqueous solution of a cation, represented by shaded spheres, is allowed to mix with a solution of an anion, represented by unshaded spheres. Three possible outcomes are represented by boxes (a)-(c).

15) Which outcome corresponds to the combination of calcium and carbonate ions:

Ca²⁺(aq) + CO₃^2-(aq) Â ?

A) box (a)

B) B) box (b)

C) box (c)

D) none of the above

Two electromagnetic waves are represented below.

16) Wave (b) has the

A) higher frequency and higher energy than wave (a).

B) lower frequency and higher energy than wave (a).

C) higher frequency and lower energy than wave (a).

D) lower frequency and lower energy than wave (a).

E) none of these are correct.

17) A baseball with a mass of 150 g is moving at a velocity of 40 m/s (90 mph). If the uncertainity in the velocity is 0.1 m/s, the uncertainty in position

A) must be greater than or equal to 4 x 10^-33 m.

B) may be zero.

C) must be 4 x 10^-33 m.

D) must be less than or equal to 4 x 10^-33 m.

E) none of these are correct.

18) What are the possible values of n and m_l for an electron in a 5d orbital?

A) n = 5 and m_l = 2

B) n = 1, 2, 3, 4, or 5 and m_l = 2

C) n = 5 and m_l = -2, -1, 0, +1, or +2

D) n = 1, 2, 3, 4, or 5 and m_l = -2, -1, 0, +1, or +2

E) none of these are correct.

19) For an electron in a given atom, the larger n, the

A) larger the average distance from the nucleus and the lower the orbital energy.

B) smaller the average distance from the nucleus and the lower the orbital energy.

C) smaller the average distance from the nucleus and the higher the orbital energy.

D) larger the average distance from the nucleus and the higher the orbital energy.

E) none of these are correct.

20) For a hydrogen atom, which electronic transition would result in the emission of a photon with the highest energy?

A) 2s  3p

B) 3p  6d

C) 5f  3d

D) 4p  4s

E) 4p  2s

21) Which of the above fourth-shell orbitals is a 4p_z orbital?

A) orbital (a) B) orbital (b) C) orbital (c) D) orbital (d)

22) For the fourth-shell orbital shown below, what are the principal quantum number, n, and the angular momentum quantum number, l?

A) n = 4 and l = 1

B) n = 4 and l = 3

C) n = 4 and l = 0

D) n = 4 and l = 2

E) 4p  4s

Part II. Please show your work to get credit. Show units and appropriate significant figures.

1}(12) A 1.000 g sample of a compound containing only carbon and hydrogen was burned in oxygen and 3.296 g of CO₂(g) and 0.8996 g of H₂0(l ) were formed. Determine the empirical formula of the compound.

2) (a) (4) Choose two ionic compounds which could be used to prepare solid iron(III) carbonate by a precipitation reaction from aqueous solution. Write the formulas for your compounds on the labels shown below so you can glue them on the bottles.

(b) (6) Write the balanced net ionic equation for the reaction which will occur when the solutions are mixed.

3) (12) Write the balanced chemical equation for the unbalanced oxidation-reduction reaction shown below (acid solution).

Fe²⁺(aq) + MnO₄^-1(aq) Â Mn²⁺(aq) + Fe³⁺(aq)

4) (10) Write the net ionic equation for the reaction of hydrochloric acid with sodium hydroxide.

5)(12) Calculate the wavelength (in nm) of the light emitted by a hydrogen atom for the transition from the n = 3 level to the n = 2 level.