*VI-1 C NC II-2 C NC V-2 C NC **VI-2 C NC II-3 C NC V-3 C NC IX-1 C NC IV-1 C NC VII-1 C NC IX-2 C NC IV-2 C NC VII-2 C NC V-1 C NC VIII-1 C NC

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1 *VI-1 C NC II-2 C NC V-2 C NC **VI-2 C NC II-3 C NC V-3 C NC IX-1 C NC IV-1 C NC VII-1 C NC IX-2 C NC IV-2 C NC VII-2 C NC V-1 C NC VIII-1 C NC Chemistry 131 Quiz 7 Summer 2011 Form A NAME: Key Chapter 16. Reaction Rates and Equilibrium *A. (2.0 pts) Determine whether each reaction shown below will be exothermic or endothermic, and whether K eq will be greater or less than one. 1. C(s) + H 2 O (g) CO(g) + H 2 (g) H = 131 kj Is the reaction endothermic or exothermic? Endothermic Is K eq greater or less than one? K eq < 1 2. P 4 (s) + 10 Cl 2 (g) 4 PCl 5 + heat H = kj Is the reaction endothermic or exothermic? Exothermic Is K eq greater or less than one? K eq > 1 One must be correct for competency B. (1.0 pts) Calculate the equilibrium constants for the reaction given below. Show your work. PCl 3 (g) + Cl 2 (g) PCl 5 (g) [PCl 5 ] = 8.3 x 10 3 M [PCl 3 ] = 1.5 x 10 2 M [Cl 2 ] = 3.2 x 10 2 M 17 K eq = [PCl 5 ] = (8.3 x 10 3 ) = 17 [PCl 3 ] [Cl 2 ] (1.5 x 10 2 x 3.2 x 10 2 )

2 **C. (2.0 pts) Acetone (C 3 H 6 O, found in nail polish remover) reacts with iodine (I 2 ) to form acetone iodide (C 3 H 5 IO) and hydriodic acid (HI (aq). The equation for the reaction is shown below: C 3 H 6 O(aq) + I 2 (aq) C 3 H 5 IO(aq) + HI (aq) heat colorless brown colorless colorless How will the equilibrium concentrations of the reactants and products change to relieve each of the stresses listed below? Choose your answer from the following selections, and write it in the space provided. No other answers will be accepted. No effect Stress Add C 3 H 6 O Add C 3 H 5 IO Add I 2 Remove C 3 H 6 O Remove I 2 Heat the mixture Cool the mixture Add a catalyst 4 or more right for competency. Effect on Equilibrium No effect Chapter 14. Acids and Bases D. (2.4 pts) For each solution, fill in the blanks. [H 3 O 1+ ] [OH 1- ] ph Is the solution acidic, basic, or neutral? x 10 9 M 5.50 x 10 6 M Basic 2. 3 x 10 8 M M 11.6* Basic x x Acidic x 10 7 M 1.00 x 10 7 M Neutral One row (not #4) must be all correct for competency. Scoring: 0.6 points per row; 0.1 pt for acidity, 0.2 pts for numbers, 0.1 pt for SF * -log 2.5 x = log 3 x = 11.5

3 E. (0.8 pts) For each reaction listed below, select the acid, the base, the conjugate acid, and the conjugate base. Write the formula in the space provided. 1. H 2 S(aq) + H 2 O(aq) HS 1 (aq) + H 3 O 1+ (aq) The acid H 2 S The conjugate base HS 1 The base H 2 O The conjugate acid H 3 O NH 4 1+ (aq) + C 2 H 3 O 2 1 (aq) NH 3 (aq) + HC 2 H 3 O 2 (aq) The acid NH 4 1+ The base C 2 H 3 O 2 1 The conjugate base NH 3 The conjugate acid HC 2 H 3 O 2 F. 1. (1 pt) When HCl(aq) is added to each of the following buffer systems, which component reacts with it? 2 SO 4 HSO and SO 4 CH 2 O 1 HCH 2 O and CH 2 O 1 2. (1 pt) When NaOH(aq) is added to each of the following buffer systems, which component reacts with it? HC 6 H 5 O HC 6 H 5 O and C 6 H 5 O 1 H 2 SO 4 1 H 2 SO 4 and HSO 4 One example in each group must be correct for the competency. 3. (0.4 pt) HCO 3 1, the bicarbonate anion, can be used in a buffer with carbonate anion, CO 3 2. What is the ph of a solution that contains equimolar amounts of these ions? K a for HCO 3 1 is 4.7 x

4 Competencies from previous quizzes: I-3 Sulfuryl chloride contains % Cl, 23.71% O, and 23.76% S. What is its empirical formula? Show your work. SO 2 Cl g Cl x 1 mol Cl = mol Cl mol Cl = mol Cl = 2 Cl g Cl mol S mol S 1 S g O x 1 mol O = mol O mol O = mol O = 2 O g O mol S mol S 1 S g S x 1 mol S = mol S SO 2 Cl g S I-4 Cyanuric acid is a precursor to bleaches, disinfectants, and herbicides. Its molar mass is g/mol, and its empirical formula is CHNO. What is its molecular formula? Show your work. C 8 H 10 N 4 O 2 1 mol C x g C = g C g x 1 formula = formula mol C mol g mol 1 mol H x 1.01 g H = 1.01 g H mol H 3(CHNO) = C 3 H 3 N 3 O 3 1 mol N x g N = g N mol N 1 mol O x g O = g O mol O g/formula II-2 Potassium oxide (K 2 O) is a major component of wood ash. When it is com-bined with water, it forms lye (potassium hydroxide, KOH). What is the theoretical yield of KOH if 150 g of K 2 O is combined with excess water? The balanced equation is shown below. Show your work. K 2 O + H 2 O 179 g KOH 2 KOH Molar mass of K 2 O = g/mol Molar mass of KOH = g/mol 150 g K 2 O x 1 mol K 2 O x 2 mol KOH x g KOH = 179 g KOH g K 2 O 1 mol K 2 O mol KOH

5 V-1 What is the molarity of a solution that contains 50.0 g of CaCl 2 in enough water to make 500 ml of solution? M 50.0 g CaCl 2 x 1 mol CaCl 2 = mol L sol'n g CaCl 2 L V ml of 1.50 M Ca(NO 3 ) 2 is diluted to 200 ml. What is the molar concentration of the dilute solution? CH0.488 mol/l 2 O M 1 V 1 = M 2 V 2 M 1 V 1 = V 2 V 2 = 1.50 M x 65.0 ml = M 200 ml V-3 Two solutions of CH 3 COOH are separated by a membrane that allows only water to pass through it. One of the solutions is 0.50 M and the other is M. After the liquids are allowed to equilibrate, which of the following conditions will be found? Check the correct answer. CH 3 COOH has flowed from the 0.50 M solution to the M solution. CH 3 COOH has flowed from the M solution to the 0.50 M solution. X Water has flowed from the M solution to the M solution. Water has flowed from the 0.50 M solution to the M solution.

6 VII-1 A container has a volume of 250 ml. What will the pressure of gas inside it be if there are moles of gas, and the temperature is 30 C? 45.7 atm P = X P x V = n x R x T = P = n x R x T V = L V n = mol P = mol x 303 K x L atm = 45.7 atm T = 30 C +273 = 303 K L mol K VII-2 Consider the following molecules, then answer the questions below. H H H C C H H H A. Ethane B. Ethanol 1. Give the name of the compound that will have the higher boiling point. Ethanol 2. What forces are present in that molecule but not present in the other one? Hydrogen bonds