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Exam I General Chemistry I – CHM 1046 Spring 2001 Dr. Landrum
Name
SS#
Instructions: Always choose the best possible answer. Keep in mind that multiple correct responses may be present. Answers may be very slightly different depending on round-off and how many significant figures are carried between calculations. Choose ‘None of the above’ only when no choice is a reasonable best answer.
R = 0.082 l atm/mol K R = 8.3 J/mol K
First order
t (^) 1/2 = 0.693/k
ln ( [A]
/[A]t ) = kt
Second order
t 1/2 = 1 / ( [A]
k )
( (1/[A]t – 1/[A]
) ) = kt
- Which of the following is true for a solution? a) it is a mixture b) it is a special example of a suspension c) it contains only one solute d) it will always separate into its components on sitting
- The process of dissolving a solute into a solution is favored by a) increasing entropy b) solvation of the solute c) strong intermolecular attraction between the solute molecules d) a & b e) b and c f) a, b, & c g) none of the above
- Which is true for a solution prepared by dissolving 46.0 g of C 2 H 6 O in 100g of H 2 O if the final volume of the solution is 129 mL? a) the molarity will be 7.75 M b) the mole fraction of C 2 H 6 O is 0. c) the density fo the solution is 1.13 g/mL d) the molality is 10.0 m e) a & c f) b & d g) all are correct
- A solution has a density of 1.8g/mL and a molarity of 3.4 mole /L. What is the molality if the solvent is H 2 O and the molecular weight of the solute is 290 g/mole? a) 3.4 molal b) 6.12 molal c) 4.18 molal d) cannot be determined
- A freshwater lake is found to contain Hg 2+^ ion at a concentration of 4.7ppm. The lake has a uniform depth of 3 m and is circular having a diameter of 28 km. How many kg of Hg2+^ ion are present in the lake? a) 8.7 x 10-6^ kg b) 1.1 x 10^7 kg c) 2.3 x 10^9 kg d) 1.7 x 10^8 kg e) none of the above
a) [WI 3 ]/[W] [I 2 ] b) [W]^2 [I 2 ]^3 /[WI 3 ]^2 c) [WI 3 ]^2 /[W]^2 [I 2 ]^3 d) [WI 3 ]/[I 2 ]^3 e) [I 2 ]^3 /[WI 3 ]^2
- The reaction shown below has an equilibrium constant, Kc = 50.2. Is the system at equilibrium and is not which wa wil the reaction shift to reach equilibrium? [NO 2 ] = 0.25M ; [N 2 O 4 ] = 12.55M 2NO 2 (g) ⇄ N 2 O 4 (g) a) System is a equilibrium b) System is not at equilibrium and will shift right c) System is not at equilibrium and will shift left d) Can’t be determined
- What is the relationship between Kp and K (^) c for the reaction,
2NO (g) + O 2 (g) ⇄ 2NO 2 (g) a) Kc = Kp (1/RT) b) Kc = Kp (RT) c) Kc = Kp (1/RT) 2 d) Kc = Kp (1/RT) - e) None of the above
- Calculate the Kp from Kc for the following reaction; Kc = 2.5 x 10-3^ at T = 1400 K
CH 4 (g) + 2H 2 S (g) ⇄ CS 2 (g) + 4H 2 (g) a) 3.29 x 10^1 b) 3.78 x 10^3 c) 0. d) 1.65 x 10- e) 2.18 x 10-
- For the reaction below which statement is true if the system is initially @ equilibrium? H 2 (g) + I 2 (g) ⇄ 2HI (g) + q
a) If the volume is doubled the reaction shifts left b) If the pressure is doubled the reaction shifts left c) If the moles of I 2 are increased the reaction shifts left d) If the moles of H 2 are increased the reactions shifts right e) When the temperature is lowered the reaction shifts left
- Which statement is true about equilibria shown below
I H 2 O (g) + 1/2O 2 (g) ⇄ H 2 O 2 (g) K
II H 2 O 2 (g) + HCO 2 H (g) ⇄ HCO 3 H (g) + H 2 O (g) K
III 1/2O 2 + HCO 2 H (g) ⇄ HCO 3 H (g) K
a) K3 = K1 + K b) K3 = K2– K c) K3 = K1 x K d) K3 = K2/K e) K3 = K1/K
- Consider the equilibrium
2O 3 (g) ⇄ 3 O 2 (g) Kp = 1.3 x 10^57 at sea level the partial prssure of O 2 is 150 mmHg. Calculate the equilibrium partial pressure of O 3 at in air at sea level if the O 2 as is given is at equilibrium with O 3. a) 1.73 x 10-53^ mmHg b) 5.1 x 10-26^ mmHg c) 5.78 x 10^52 mmHg d) 8.67 x 10^54 mmHg
- At a temperature of 1500K the Kp for the dissociation of F 2 into atomic fluorine is 7.83. If a 1 L container is filled with 0.01 mole of F 2 (0.244 atm) at room temperature what will the partial pressure of fluorine atoms be after the system is heated to 1500K and equilibrium has been reached. (Remember: you must use units of Pressure!) F 2 (g) ⇄ 2F (g)
a) 0.856 atm b) 1.53 atm c) 1.39 atm d) 1.55 atm
- What is Kp for the following reaction if the equilibrium pressures of the reactants are: PPCl5 = 0.2 atm, P (^) Cl2 = 5.0 atm, PPCl3 = 4.64 atm PCl (^5) (g) + Cl (^2) (g) ⇄ PCl (^3) (g)
a) 8.62 x 10- b) 2.16 x 10- c) 1856 d) 116
c) 0.046 molar d) 3.5 x 10-4^ molar e) 0.395 molar
- For the reaction 2H 2 O 2 Æ 2H 2 O + O 2 (g) Which of the following must be true? a) R = k[H 2 O 2 ] 2 b) –1/2 d[H 2 O 2 ]/dt = d[O 2 ]/dt c) 1/2d[O 2 ]/dt = d[H 2 O 2 ]/dt d) d[H 2 O 2 ]dt = d[O 2 ]/dt
- Determine the Rate law for the following reaction using the method of initial rates and the data below.
Exp # [A] [B] Initial rate of C formation 1 0.011 0.071 0.041 M -1^ s - 2 0.011 0.142 0.020 M -1^ s - 3 0.022 0.071 0.164 M -1^ s -
a) R = k[A]^2 [B] b) R = k[A]^1 [B]^2 c) R = k[A]^2 [B]- d) R = k[A]-1^ [B]^2 e) R = k[A]^2 [B]-
- Use the graph below to determine the half-life of a reaction which obeys the following rate law, Rate = k[A]. [A] °
= 0.5M.
a) 408 s b) 177 s c) 511 s d) 588 s
- The rate constant of a reaction is dependent upon which of the following? a) Ea, activation energy b) The concentration of the reactants c) The temperature of the reaction d) The Arrhenius constant e) a & b f) a & c g) b & c h) a, b, & c i) a, c, & d j) None of the above
- Which statement is entirely correct about the following rate law, Rate = k[H+]^2 [O 3 ] a) the reaction is 1st^ order b) the reaction is 2nd^ order c) the reaction involves a single ternary step d) the reaction is 2nd^ order in H+^ and 1 st^ order in O 3
- A catalyst a) alters the activation energy b) influences the reaction mechanism c) must be insoluble d) a & b e) all of the above
- If a reaction is 1st^ order and the reaction is 7% complete after 2 hrs when will the reaction reach 99% completion. a) 28.3 hrs
t ln[A] 0 -0. 100 -0. 200 -1. 300 -1. 400 -1. 500 -1. 600 -1. 700 -1. 800 -2. 900 -2. 1000 -2.393 (^) -
-2.
-
-1.
-
-0.
0
0 200 400 600 800 1000 1200 time (seconds)
ln [A]t
