4.4. Buffers in the human body
(A) help to maintain a constant blood pH.
(B) help to keep the body temperature constant.
(C) help change the blood plasma pH when foods are eaten.
(D) precipitate proteins so enzymes are inactive.
5.5. One milliliter (1.00 mL) of acid taken from a lead storage battery is pipetted into a flask. Water and phenolphthalein indicator are added, and the solution is titrated with 0.50 M NaOH until a pink color appears; 12.0 mL are required. The number of grams of H2SO4 (formula weight = 98) present in one liter of the battery acid is (to within 5%):
6.6. Which of the following statements is (are) true?
(A) Enthalpy is a state function.
(B) In exothermic reactions, the reactants are lower in potential energy than the products.
(C) A chemist takes the surroundings point of view when determining the sign for work or heat.
(D) The heat of reaction and change in enthalpy can always be used interchangeably.
7.7. For which process is ΔS negative?
(A) evaporation of 1 mol of CCl4(l)
(B) mixing 5 mL ethanol with 25 mL water
(C) compressing 1 mol Ne at constant temperature from 1.5 atm to 0.5 atm
(D) raising the temperature of 100 g Cu from 275 K to 295 K
9.9. The standard potential for the following reaction:
Zn + 2Ag+ → Zn2+ + 2Ag
is 1.56 V. Calculate the cell potential for the following reaction:
2Zn2+ + 4Ag → 2Zn + 4Ag+
(A) 1.56 V
(B) -1.56 V
(C) 3.12 V
(D) -3.12 V
10.10. A sky diver jumps out of a plane. Before reaching
terminal velocity, her
(A) displacement remains constant.
(B) acceleration increases.
(C) acceleration remains constant.
(D) acceleration decreases.
11.11. The motion of a ball of mass m dropped off a building is observed by a man at ground level and a woman at the top of the building. The man’s origin for measuring gravitational potential energy is at ground level and the woman’s origin for measuring gravitational potential energy is at the top of the building. The building’s height is h and air friction is neglected. What kinetic energy does the woman record after the ball has fallen a distance d?
(D) mg (h–d)
12.12. Two observers are each travelling at 0.49c toward each other. Observer A sends a pulse of light toward observer B and observes that the pulse leaves her vehicle at a speed of 1.00 c. At what speed does observer B record the pulse moving?
13.13. The centripetal acceleration of a planet in an elliptical orbit about the sun is greatest when the planet is
(A) nearest the sun.
(B) nearest the Earth.
(C) farthest from the sun.
(D) farthest from the Earth.
15.15. A 5 kg piece of lead (specific heat 0.03 cal/g C°) having a temperature of 80° C is added to 500 g of water having a temperature of 20°. What is the final equilibrium temperature in °C of the system?
19.19. Which of the following statements is incorrect?
(A) Ionic bonding results from the transfer of electrons from one atom to another.
(B) Dipole moments result from the unequal distribution of electrons in a molecule.
(C) The electrons in a polar bond are found nearer to the more electronegative element.
(D) Linear molecules cannot have a net dipole moment.
20.20. Which of the following statements is true?
(A) When two opposing processes are proceeding at identical rates, the system is at equilibrium.
(B) Catalysts are an effective means of changing the position of an equilibrium.
(C) The concentration of the products equals that of reactants and is constant at equilibrium.
(D) An endothermic reaction shifts toward reactants when heat is added to the reaction.
21.21. The reaction
N2(g) + 3H2(g) 2NH3(g)
takes place in a 1.0-L vessel initially filled with an equimolar mixture of N2 and H2 at a pressure of 12.0 atm. When equilibrium is reached, the partial pressure of H2 is 3.0 atm. Determine the value of Kp for this reaction.
24.24. Which of the following will not produce a buffered solution?
(A)100 mL of 0.1 M Na2CO3 and 50 mL of 0.1 M HCl
(B)100 mL of 0.1 M NaHCO3 and 25 mL of 0.2 M HCl
(C)100 mL of 0.1 M Na2CO3 and 75 mL of 0.2 M HCl
(D)100 mL of 0.1 M Na2CO3 and 50 mL of 0.1 M NaOH
28.28. A sphere moves past an observer at 0.6c. What
shape does the observer see?
(A) A sphere, slightly smaller than the sphere really is.
(B) A cone, slightly flattened.
(C) An ellipsoid, flattened in the direction of motion.
(D) A hypocycloid, flattened in the direction of motion.
31.31. Five g of water are vaporized in a 2.0 L pressure cooker and heated to 500 K. and the molar mass of water is 18 g/mol. What is the pressure in atm inside the container?
34.34. The rate expression for a particular reaction is rate = k[A][B]2. If the initial concentration of B is increased from 0.1 M to 0.3 M, the initial rate will increase by which of the following factors?
36.36. Order the intermolecular forces (dipole-dipole, London dispersion, ionic, and hydrogen-bonding) from weakest to strongest.
(A) dipole-dipole, London dispersion, ionic, and hydrogen-bonding
(B) London dispersion, dipole-dipole, hydrogen-bonding, ionic
(C) hydrogen-bonding, dipole-dipole, London dispersion, and ionic
(D) dipole-dipole, ionic, London dispersion, and hydrogen-bonding
37.37. Which of the following compounds has the lowest boiling point?
(D) All the boiling points are about the same since the molar masses of the three compounds are essentially equal.
39.39. One mole of an ideal gas is expanded from a volume of 1.00 L to a volume of 10.00 L against a constant external pressure of 1.00 atm. Calculate the work. (1 L• atm = 101.3 J)
(A) -456 J
(B) -1010 J
(C) -912 J
(D) -2870 J
42.42. A synchronous satellite revolves around the Earth in a
(A)Its acceleration is zero because its speed is constant.
(B)Its acceleration is zero because its velocity is constant.
(C)Its speed varies because its acceleration is constant.
(D)Its acceleration and its velocity are both not constant.
44.44. A planet has the same mass as the Earth. It also has a radius twice the Earth’s radius. If the Earth’s acceleration due to gravity is g, what is the acceleration due to gravity on the planet’s surface?
(A) 1/4 g
(B) 1/2 g
(D) 2 g
47.47. Five moles of an ideal gas expand isothermally at 100° C to five times its initial volume. Find the heat in J that flows into the system. (R = 8.31 J/molK)
(A) 2.5 x 104
(B) 1.1 x 104
(C) 6.7 x 103
(D) 2.9 x 103