Final Review Packet * Semester 1

advertisement

College Chemistry Final Exam Review – Semester 2

This review packet belongs to ______________________ and he/she is going to have fun completing it!

Solutions and Kinetics

1) 2) 4) What is the mass of H 3 PO 4 in 725 mL of 0.75 M H 3 PO 4 solution? How many grams of CaCl 2 would be needed to prepare 0.650 L of a 1.4 M solution? 3) Use the graph to the right for this question. At 30°C, how many grams of NH extra)? 4 Cl would you need to add to 100 g of water to saturate the solution (without adding You need 400 mL of 3M H solution? 2 SO 4 . What volume of 8.0 M H 2 SO 4 must be dissolved in water to form this 5) 6) Adding which of the following to 1.0 L of water would result in a solution with the highest boiling point? a) 55 g NaCl b) 15 g BaCl 2 c) 75 g RbF If you have a first order reaction and you triple the concentration, the rate will _____________________. 7) If you have a second order reaction and you cut the concentration by one-half, the rate will ___________. 8) What is the rate of a first-order reaction that has a reactant concentration of 0.850 M and a rate constant of 0.17 1/s? 9) Use the table at right: Consider a reaction A + B + C D Use this table for question #9 a) b) What is the order of this reaction with respect to [A]? What is the order of this reaction with respect to [B]? Trial Initial Concentration (M) A B C Initial Rate M/s) c) What is the order of this reaction with respect to [C]? 1 1 2 3 4 0.025 0.20 0.20 0.025 0.40 0.20 0.05 0.05 0.40 0.40 0.40 0.20 0.0070 0.0140 0.112 0.056

Equilibrium

Use the following reaction to answer 10-16:

2A(g) + B(s) ↔ 3C(g) + D(l) + 12kJ

10) Is this reaction endothermic or exothermic? 11) Write the K eq expression. 12) Calculate K eq with the following concentrations: A = 0.50 M and C = 2.0 M 13) What would happen to the concentration of C if you increase temperature? 14) What would happen to the concentration of C if you add pressure? 15) What would happen to the concentration of A if you remove B? 16) What would happen to the value of K eq if you cool down the reaction?

Electrochemistry (Redox)

17) Assign oxidation states to this reaction and determine which element is oxidized/reduced and which one is the reducing agent/oxidizing agent.

KMnO 4 + HCl

MnCl 2 + Cl 2 + H 2 O + KCl

18) Write oxidation and reduction half-reactions for this equation and balance the equation.

Sb(s) + HNO 3 (aq)

Sb 2 O 3 (s) + NO(g) + H 2 O(l)

19) Calculate the cell potential for these reactions and determine if each is spontaneous or not: a) Sn 2+ + IO 3  Sn 4+ + I b) S 2- + NO 3  S + NO 20) Determine the cell potential for the following reaction at nonstandard conditions if [Zn 2+ ] = 2.5 M and [Cl ] = 4.0 M.

Zn + Cl 2

Zn 2+ + 2Cl -

2

Acids and Bases

21) Label the acid, base, and their conjugates for the following reaction:

NH 3 + H 2 O

NH 4 + + OH –

22) What is the pH and pOH of a 0.0190 M HNO 3 solution? 23) Which of the following is the weakest acid? HNO 2 with K a = 4.0 x 10 -4 or H 2 S with K a = 9.1 x 10 -8 24) What is the [H + ] and [OH ] for ammonia with a pH of 11.6? 25) What is the pH of a solution prepared by dissolving 21 g of acetic acid in enough water to make 1.5 L of solution? Assume % dissociation of 8%. 26) Write and balance the equation for the reaction of perchloric acid and calcium hydroxide. 27) If it takes 50 mL of 0.5 M KOH solution to completely neutralize 125 mL of H 2 SO 4 , what is the concentration of the H 2 SO 4 solution? 28) A supply of NaOH is known to contain contaminants. A 0.199 g NaOH sample is titrated with 22.26 mL of a 0.1989 M solution of HCl. What percentage of the original sample is NaOH? Assume that none of the contaminants react with HCl. 29) What is the pH of a 0.300 M solution of benzoic acid? K a = 6.46 x 10¯ 5

HBz + H 2 O ↔ H 3 O +

+ Bz¯ (Bz¯ refers to the benzoate ion) 3

Nuclear

30) Write the symbol for the isotope of lithium with 5 neutrons. 31) If the half-life of cesium-134 is 2 years, and you start with 100 g of cesium-134, how much would be left after 10 years? 32) How many protons, neutrons, and electrons are in a neutral atom of Cs-137? 33) If N-14 is bombarded with a neutron to form C-14, what particle is released along with the C-14? 34) What is formed when radon-222 undergoes alpha decay? 35) What is formed if xenon-131 is bombarded by a beta particle? 4

ANSWER KEY College Chemistry Final Exam Review – Semester 2

1) 2) 3) 4) 5) 6) 7) 8) 9) 10) exothermic 11) 35.5 g 33.6 g 38 g 150 mL 100 g LiF double decrease by 1/9 rate = 0.14 M/s a) 2 b) 1 c) 1 K = [C] 3 /[A] 2 12) 32 13) decrease 14) decrease 15) nothing – manipulating a solid or liquid does not change equilibrium position 16) increase 17) left: H=+1, S=-2, N=+5, O=-2; right: S=0, N=+2, O=-2, H=+1; sulfur is oxidized and is the reducing agent, nitrogen is reduced and is the oxidizing agent 18) Final answer: 3S(s) + 4HNO 3 (aq)  3SO 2 + 4NO(g) + 2H 2 O(l) hint: oxidation starts with S  SO 2 reduction starts with HNO 3  NO 19) a) 2.22V spontaneous 22) pH= 0.69, pOH=13.31 b) -1.636V, not spontaneous 20) 2.074V 21) HF = acid, H 2 O=base, F -1 = conjugate base, H 3 O +1 = conjugate acid 23) H 2 SO 3 (higher K a ) 24) [H + ] =10 -3 and [OH -1 ] = 10 -11 25) 1.55 26) H 2 SO 4 + 2KOH  2H 2 O + K 2 SO 4 27) 2.36 28) 3 8

Li

or Li-8 29) 125 g 30) p=55, n = 82, e = 55 31) a proton 32) 218 84

Po

33) 131 53

I

or Po-218 or I-131 5

Download