GENERAL SANTOS HOPE CHRISTIAN SCHOOLBlock 8, City Heights, General Santos City

THIRD PERIODICAL EXAMINATIONCHEMISTRY III

THIRD YEAR A and BSY: 2011 - 2012

NAME : _______________________ SCORETeacher: ROGELIO B. PONTEJO Date: ___________.

I. Multiple Choice: Choose the correct answer. Shade the bubble corresponding to the answer of your choice in the separate ANSWER SHEET. Detach and submit the BUBBLE ANSWER SHEET with your answers and bring the test paper home and bring it back on January 4, 2012.

1. Which of the following statements concerning equilibrium is not true?

A) A system that is disturbed from an equilibrium condition responds in a manner to restore equilibrium.

B) Equilibrium in molecular systems is dynamic, with two opposing processes balancing one another.

C) The value of the equilibrium constant for a given reaction mixture is the same regardless of the direction from which equilibrium is attained.

D) A system moves spontaneously toward a state of equilibrium. E) The equilibrium constant is independent of temperature.

2. The value of the equilibrium constant, K, is dependent onI. The temperature of the system.II. The nature of the reactants and products.III. The concentration of the reactants.IV. The concentration of the products.

A) I, II B) II, III C) III, IV D) It is dependent on three of the above choices. E) It is not dependent on any of the above choices.

3. Write a balanced chemical reaction which corresponds to the following equilibrium constant

expression:

(A) 3 O2(g) 2 SO3 (g) (B) 2 SO3 (g) 3 O2(g) (C) 2 SO2 (g) + O2(g) 2 SO3 (g) (D) 2 S(s) + 3 O2(g) 2 SO3 (g) (E) 2 SO3 (g) 2 S(s) + O2(g)

4. The minimum combined kinetic energy reactant particles must possess in order for their collision to result in a reaction is called the

a) dissociation energy.b) collision energy.c) activation energy.d) orientation energy.

5. Whether a reaction is exothermic or endothermic is determined byA) the activation energy.B) the physical state of the reactants.C) how reactant and product potential energies compare.D) whether a catalyst is present.

6. Which of the following changes will decrease reaction rate for the chemical reaction

2CO + O2 2CO2

A) adding some O2 to the reaction mixtureB) raising the temperature of the reaction mixtureC) adding a catalyst to the reaction mixtureD) removing some CO from the reaction mixture

7. Catalysts are correctly characterized by each of the following statements except one. The exception is

A) they can be either solids, liquids or gases.B) they lower the activation energy for a reaction.C) they do not actively participate in a reaction.D) they are not consumed in a reaction.

8. For a system at chemical equilibrium,

A) forward and reverse reaction rates are equal.B) forward and reverse reaction rates are zero.C) reactant and product concentrations are equal.D) reactant and product concentrations are zero.

9. Which of the following is the correct equilibrium constant expression for the reaction

4HCl(g) + O2(g) 2H2O(g) + 2Cl2(g)

a) Keq =

Cl2 H2O HCl O2

b) Keq =

HCl O2 Cl2 H2O

c) Keq = Cl2 2

H2O 2

HCl 4O2

d) Keq = HCl 4

O2 Cl2 2

H2O 2

10. Le Chatelier’s principle states that

A) only exothermic reactions can reach chemical equilibrium.B) only reactions in which a catalyst is present can reach chemical

equilibrium.C) if a chemical equilibrium is disturbed, the system will try and

reestablish equilibrium.D) if a chemical equilibrium is disturbed, the temperature of the system

will always decrease.

11. CO2 and H2 are allowed to react until an equilibrium is established as follows:

CO2(g) + H2(g) H2O(g) + CO(g)

What will be the effect on the equilibrium of removing CO from the equilibrium mixture?

A) The equilibrium will shift to the left.B) H2 concentration will increase.C) CO and CO2 concentrations will increase.D) H2 concentration will decrease and H2O concentration will increase.

12. According to Le Chatelier’s principle, which of the following changes will shift the position of the equilibrium to the left for the reaction

N2(g) + 3H2(g) 2NH3(g) + heat

A) increase the concentration of N2

B) decrease the concentration of NH3

C) increase the concentration of H2

D) increase the temperature

13. For a collision between molecules to result in reaction, the molecules must possess a certain minimum energy and

A) exchange electrons.B) interact with a catalyst for at least 1 second.C) have a favorable orientation relative to each other when they collide.D) more than one correct responseE) no correct response

14. Which of the following statements about activation energy is correct?

A) It is the same for all reactions.B) It is low for reactions that take place rapidly.C) It is the maximum energy a reacting molecule may possess.D) more than one correct responseE) no correct response

15. Increasing the temperature at which a chemical reaction occurs

A) will lower the activation energy.B) cause more reactant collisions to take place in a given time.C) increase disorder in the system, thus decreasing the reaction rate.D) more than one correct responseE) no correct response

16. Which is most acidic?

A. pOH = 1 B. pOH = 7 C. pOH = 10 D. pOH = 13

17. What is the pH of 0.01 N HCl?

A. 1 B. 2 C. 12 D. 13

18. Which is an acid?

A. NaHCO3 B. NH3 C. CH3COOH D. H2O

19. Find the pH if [H+] is 4.8 x 10-13 M.

A. 12.32 B. 11.32 C. 6.32 D. 9.32

20. Calculate the pH of 0.01M NaOH.

A. 1 B. 12 C. 2 D. 14

21. A standard solution is one

A. whose concentration is being tested C. which is acidic in natureB. with a brown concentration D. which is basic in nature

22. Consider the following reaction:

The average rate of appearance of C is given by . Comparing the rate

of appearance of C and the rate of disappearance of A, we get

.

A) B) C) D)

23. At elevated temperatures, methylisonitrile isomerizes to acetonitrile

:

At the start of an experiment, there are 0.200 mol of reactant and 0 mol of product in the reaction vessel. After 25 min, 0.108 mol of reactant

remain. There are __________ mol of product in the reaction vessel.

A. 0.540 B. 0.200 C. 0.308 D. 0.092

24. A reaction was found to be second order in carbon monoxide concentration. The

rate of the reaction __________ if the is doubled, with everything else kept

the same.

A doubles C. triplesB. remains unchanged D. increases by a factor of 4

25. Which of the following is not an acid?

A. HNO3 B. CH3COOH C. H2SO4 D. All of these are acids

26. If a solution conducts electricity, it is probably:

A. an acid B. a base C. neutral D. it is impossible to guess.

27. If a compound has a pH of 6.5, it has a pOH of:

A. 6.5 B. 7.5 C. 3.16 x 10-7 D. 3.16 x 10-8

28. What is the pH of a 0.001 M formic acid solution? Ka = 1.8 x 10-4.

A. 3.74 B. 10.3 C. 3.37 D. 10.6

29. Buffers keep the pH of a solution from changing by:

A. converting strong acids to weak onesB. converting weak acids to strong onesC. converting weak bases to strong onesD. more than one of the above answers is correct.

30. If the rate law for the reaction

is first order in A and second order in B, then the rate law is

A. B. C. D.

31. The kinetics of the reaction below were studied and it was determined that the reaction rate did not change when the concentration of B was tripled. The reaction is _____ order in B.

A. zero B. first C. second D. third

The data in the table below were obtained for the reaction:[For items 32, 33 and 34]

32. The order of the reaction in A is __________.

A. 1 B. 2 C. 3 D. 4

33. 28) The order of the reaction in B is __________.

A. 2 B. 3 C. 4 D. 0

34. The overall order of the reaction is __________.

A. 1 B. 2 C. 3 D. 4

35. Which statement explains why the speed of some chemical reactions is increased when the surface area of the reactant is increased?

A. This change increases the density of the reactant particles. B. This change increases the concentration of the reactant. C. This change exposes more reactant particles to a possible collision. D. This change alters the electrical conductivity of the reactant particles.

36. Which conditions will increase the rate of chemical reaction?A. decreased temperature and decreased concentration of reactants? B. decreased temperature and increased concentration of reactants? C. increased temperature and decreased concentration of reactants? D. increased temperature and increased concentration of reactants?

37. In a chemical reaction, a catalyst changes theA. potential energy of the products B. potential energy of the reactants C. heat of reaction D. activation energy

38. Which is a property of a reaction that has reached equilibrium?A. The amount of products is greater than the amount of reactants. B. The amount of products is equal to the amount of reactants. C. The rate of the forward reaction is greater than the rate of the reverse reaction. D. The rate of the forward reaction is equal to than the rate of the reverse reaction.

39. Which procedure will increase the solubility of KCl in water?A. stirring the solute and solvent mixture B. increasing the surface area of the solute C. raising the temperature of the solvent D. increasing the pressure on the surface of the solvent

40. Given the equilibrium system at 25°C: NH4Cl(s) <-> NH4+(aq) + Cl-(aq) (H = +3.5

kcal/mol). What change will shift the equilibrium to the right?A. decreasing the temperature to 15°C? B. increasing the temperature to 35°C? C. dissolving NaCl crystals in the equilibrium mixture? D. dissolving NH4NONH3 crystals in the equilibrium mixture?

41. Given the reaction at equilibrium: N2(g) + O2(g) 2NO(g) as the concentration of N2(g) increases, the concentration of O2(g) willA. decrease B. increase C. remain the same

42. Given the reaction at equilibrium: 2CO(g) + O2(g) 2CO2(g) When the reaction is subjected to stress, a change will occur in the concentration of

A. reactants, only C. both reactants and productsB. products, only D. neither reactant nor product

43. In which reaction will the point of equilibrium shift to the left when the pressure on the system is increased?

A. C(s) + O2(g) CO2(g) B. CaCO3(s) CaO(s) + CO2(g) C. 2Mg(s) + O2(g) 2MgO(s) D. 2H2(g) + O2(g) 2H2O(g)

44. Given the reaction at equilibrium: 2 SO2(g) + O2(g) 2 SO3(g) + heatWhich change will shift the equilibrium to the right?

A. adding a catalyst B. adding more O2(g) C. decreasing the pressure D. increasing the temperature

45. When a catalyst is added to a system at equilibrium, a decrease occurs in theA. activation energy B. heat of reaction C. potential energy of the reactants D. potential energy of the products

46. Which solution will change red litmus to blue?A. HCl(aq) B. NaCl(aq) C. CH3OH(aq) D. NaOH(aq)

47. An acidic solution could have a pH ofA. 7 B. 10 C. 3 D. 14

48. What is the pH of a 0.00001 molar HCl solution?A. 1 B. 9 C. 5 D. 4

49. What is the pH of a solution with a hydronium ion concentration of 0.01 mole per liter?

A. 1 B. 2 C. 10 D. 14

50. There are alternate acid base theories that define an acid as any species that canA. donate a proton C. accept a protonB. donate an electron D. accept an electron

51. A student wishes to prepare approximately 100 milliliters of an aqueous solution of 6M HCl using 12 M HCl. Which procedure is correct?

A. adding 50 mL of 12 M HCl to 50 mL of water while stirring the mixture steadily. B. adding 50 mL of 12 M HCl to 50 mL of water and then stirring the mixture

steadily. C. adding 50 mL of water to 50 mL of 12 M HCl while stirring the mixture steadily. D. adding 50 mL of water to 50 mL of 12 M HCl and then stirring the mixture

steadily.

52. Offensive odor and taste are removed by the process of

A. aeration C. sedimentationB. filtration D. chlorination

53. In the final stage of purifying water for drinking purposes, what substance is added to the filtrate to kill molds, microorganisms, and bacteria?

A. Chlorine B. fluorine C. lime D. sodium carbonate

54. Fertilizers contain phosphates which

A. hastens the growth of algae and choke off waterwaysB. destroy the ability of hemoglobin to transport oxygen to the cellsC. are dangerous to infantsD. are biodegradable

55. A natural phenomenon that becomes harmful due to pollution is _____________.

A. global warming C. greenhouse effectB. ecological balance D. desertification

56. Heavy metal ions are also pollutants of water. All of the following are pollutants, EXCEPT:

A. lead B. cadmium C. copper D. magnesium

57. Bacteria are removed from water by

A. filtration B. distillation C. chlorination D. adding activated carbon

58. One of the best solutions to get rid of non-biodegradable wastes is ____________.

A. burning B. dumping C. burying D. recycling

59. Name one non-biodegradable waste which may pollute the earth to dangerous levels of toxicity, if not handled properly.

A. DDT B. CFC C. Radioactive substance D. battery

60.   In a lake polluted with pesticides, which one of the following will contain the maximum amount of pesticides?

A. Small fish B. microscopic animal C. big fish D. water birds

NOTE: Write your PART II answers in the reverse portion of your ANSWER SHEET.

PART II

61 – 65. The reaction H2 + 2NO 2H2O + N2 at 800oC gave the following results:

ExperimentInitial Concentration (mole/L) Reaction Rate

(mole/L-s)[NO] [H2]1 0.0010 0.0060 7.9 x 10-7

2 0.0020 0.0060 3.2 x 10-6

3 0.0040 0.0060 1.3 x 10-5

4 0.0040 0.0030 6.4 x 10-6

5 0.0040 0.0015 3.2 x 10-6

a. What is the order of the reaction with respect to NO? H2?

b. What is the rate constant?

66 – 70. Explain Le Chateliers’ Principle and cite example.

GOD BLESS