Grade 12 Prototype Examination Chemistry · Grade 12 Prototype Examination Chemistry Course Code 8256 ... Calculators that have built-in notes ... - 10 - DRAFT - Chemistry 30, Prototype

September 2015

Revised December 2016

Grade 12 Prototype Examination

Chemistry

Course Code 8256

Barcode Number

Month Day

Date of Birth

- i -

DRAFT - Chemistry 30, Prototype Exam

September 2015 – Revised December 2016

Chemistry

Time: Two and One-Half Hours

Chemistry 8256 is a closed-book examination. NO authorized textbooks, students’ notebooks, or

laboratory manual may be used. You are NOT allowed to use a print, electronic, or

translation dictionary.

Calculators may be used. Only silent hand-held calculators designed for mathematical computations

such as logarithmic, trigonometric, and graphing functions are permissible. Computers, calculators

with QWERTY keyboards, calculators capable of symbolic manipulation, and electronic writing pads are

not allowed. Calculators that have built-in notes (definitions or explanations in alpha notation) that

cannot be cleared are not permitted. All calculators must be cleared of programs.

Do not spend too much time on any question. Read the questions carefully.

The examination consists of 45 multiple-choice and 5 numeric response questions of

equal value which will be machine scored. Record your answers on the Student Examination

Form which is provided. Each multiple choice question has four suggested answers, one of which

is better than the others. Select the best answer and record it on the Student Examination Form

as shown in the example below:

Student Examination Form:

Multiple Choice

Which subject is this examination being

written in?

A. Foundations of Mathematics

B. Chemistry

C. Pre-Calculus

D. Workplace and Apprenticeship

Mathematics

1. A B C D

Numeric Response

Calculation Questions and Solutions

What volume of water must be added to

100 mL of 3.0 M solution to create a 1.0 M

solution?

(Record your answer in the numeric response

section on the answer sheet.)

- ii -



Use an ordinary HB pencil to mark your answers on the Student Examination Form. If you

change your mind about an answer, be sure to erase the first mark completely. There should be

only one answer marked for each question. Be sure there are no stray pencil marks on your

answer sheet. If you need space for rough work, use the space in the examination booklet beside

each question.

Do not fold either the Student Examination Form or the examination booklet. Check

that all information at the bottom of the Student Examination Form is correct and

complete. Make any necessary changes, and fill in any missing information. Be sure to

complete the Month and Day of Your Birth section.

As per the Registrar’s Handbook for School Administrators 2016-17 (page 40), the new

science courses, Chemistry 30 (8256) and Chimie 30 (8259) are closed-book examinations.

No external materials such as textbooks, student notebooks or lab manuals are allowed.

The Ministry of Education has prepared data tables found in the Chemistry Data Booklet

2016.

Students may use the Data Booklet while taking the course, but when writing the

Chemistry examination, students must use the Data Booklet supplied with the

examination. No external notes are allowed into the examination room.

http://publications.gov.sk.ca/documents/11/86941-2016-17%20Registrar's%20Handbook.pdf

https://www.edonline.sk.ca/webapps/blackboard/execute/content/file?cmd=view&content_id=_87221_1&course_id=_2869_1

https://www.edonline.sk.ca/webapps/blackboard/execute/content/file?cmd=view&content_id=_87221_1&course_id=_2869_1

- 1 -



GRADE 12 DEPARTMENTAL EXAMINATION

CHEMISTRY 30, PROTOTYPE EXAM

VALUE

100

(50 2)

Answer the following 50 questions on the computer sheet entitled

“Student Examination Form.”

1. Which scientist developed the “uncertainty principle” which states that

it is impossible to determine both the position and the speed of an

electron at the same time?

A. Max Planck

B. Albert Einstein

C. Louis de Broglie

D. Warner Heisenberg

2. Which of the following is the correct Lewis structure for an atom of

beryllium?

A.

B.

C.

D.

A Data Booklet that contains all of the required formulas and tables for this course

is supplied with this examination. The booklet does not need to be returned to the

ministry.

- 2 -



3. In which of the following groups do the species have the same number of

electrons?

A. Br, Kr, Rb

B. Na , Ne, F

C. Li , Na , K

D. 2 2 2O , S , Se

4. What is the correct Lewis structure for the compound2

Na O ?

A.

B.

C.

D.

- 3 -



5. Which of the following elements has three valence electrons?

A. sulfur

B. lithium

C. aluminum

D. phosphorus

6. Which of the following is the correct VSEPR structure for ammonia

3(NH )?

A.

B.

C.

D.

- 4 -



7. Which of the following molecular compounds has the lowest boiling

point?

A. 3

CHCl

B. HOCl

C. HCl

D. 2

Cl

8. What is the type of force generated by temporary dipoles?

A. dispersion force

B. van der Waals force

C. intermolecular force

D. London dispersion force

9. Based on the bonding found in the molecule, which of the following is

the softest?

A. Fe

B. 2

SiO

C. 24 50

C H

D. 3CaCO

NR1. How many hydrogen atoms are found in a molecule of decane?

(Record your answer in the numeric response section on the answer

sheet.)

- 5 -



10. Which class of organic compound contains one triple bond?

A. alkyne

B. alkene

C. alkane

D. aromatic

11. Consider the following structure.

What is the IUPAC name of the molecule?

A. 2 – methyl – 4 – ethylhexane

B. 3 – ethyl – 5 – methylhexane

C. 5 – methyl – 3 – ethylhexane

D. 4 – ethyl – 2 – methylhexane

- 6 -



12. Consider the following organic compound.

3 2 2 3CH CH CH CH CH CH

Which structural formula does NOT represent a completely different

isomer?

A.

B. 3 2 2 3

CCH CH CH H CH CH

C. 3 2 2 3

CH CH CH CH CH CH

D. 2 2 2 2 3

CH CH CH CH CH CH

13. Consider the following molecule:

To which class of organic compounds does this molecule belong?

A. ester

B. ether

C. ketone

D. organic acid

C

H

H

H C

O

O

CH

H

CH

H

CH

HH

C

H

H

H C

O

O

CH

H

CH

H

CH

HH

- 7 -



14. Which of the following statements is true of a system at equilibrium?

A. value of Keq at 20 °C = value of Keq at 150 °C

B. rate of forward reaction = rate of reverse reaction

C. concentration of reactants = concentration of products

D. products escaping the system = reactants entering the system

15. Hydrogen and fluorine form an equilibrium as indicated.

2 2(g) (gH F ) 2 HF(g)

Decreasing pressure by one-half on an equilibrium mixture of 2

H , 2

F ,

and HF will

A. halve the numerical value of K .eq

B. double the numerical value of K .eq

C. quadruple the numerical value of K .eq

D. not change the numerical value of K .eq

16. Consider the following reaction at equilibrium.

2 4 2N O (g) 2 NO (g) H 58.9 kJ/mol

Which of the following changes would increase the equilibrium

concentration of 2

NO (g) ?

A. increase the temperature of the system

B. decrease the concentration of 2 4N O (g)

C. decrease the volume of the container

D. add a catalyst

- 8 -



17. A concentration versus time graph of a reaction is shown.

The reaction is initially at equilibrium and has a stress applied at

1t and 2t . The equation for the reaction is

A. XZY

B. YXZ

C. YXZ

D. not possible to determine from the information given.

18. Consider the following reaction.

2FeO(s) CO(g) Fe(s) CO (g)

The equilibrium constant expression is

A. 2[CO ]Keq

[CO]

B. 2

[CO]Keq

[CO ]

C. 2[Fe][CO ]Keq

[FeO][CO]

D. 2

[FeO][CO]Keq

[Fe][CO ]

- 9 -



19. Consider the following reaction at equilibrium.

2

3 2 2 4 24NH (g) 7O (g) 2N O (g) K 2.16 10eq6H O(g)

The equilibrium concentrations are as follows:

3[NH ] 2.40 mol/L

2[O ] 1.50 mol/L

2[H O] 1.80 mol/L

What is the equilibrium concentration of 2 4

N O ?

A. 0.043 mol/L

B. 0.60 mol/L

C. 9.6 mol/L

D. 27.7 mol/L

NR2 At 1100 K, a mixture of 3.0 M hydrogen 2

(H (g)), 6.0 M iodine 2

(I (g)),

and 6.0 M hydrogen iodide (HI(g)) are brought to equilibrium as shown:

2 2H (g) I (g) 2HI(g).

The equilibrium concentration of hydrogen is found to be 1.0 M.

2H 2

I HI

[initial] 3.0 M 6.0 M 6.0 M

[change]

[equilibrium] 1.0 M

Determine the value of Keq for the reaction to the nearest whole

number.


sheet.)

- 10 -



20. Sulfuric acid is one of the world’s most important industrial chemicals.

It is used for petroleum refining and in the production of paper,

fertilizer, and steel. Sulfuric acid is generated by dissolving sulfur

trioxide 3

(SO (g)) in water. Sulfur trioxide is produced according to the

following equilibrium:

2 2 32 SO (g) O (g) 2 SO (g) heat

Which of the following stresses on the system will maximize the yield of

3SO (g) ?

A. remove 2

O (g)

B. adding a catalyst

C. increase pressure

D. increase temperature

21. Consider the following equilibrium:

2 32(g) 3H (gN 2NH g) ( )

At equilibrium, the concentration of 3

NH is 0.933 M and 2

H is 1.60 M

and the value of Keq is 0.399. What is the equilibrium concentration of

2N ?

A. 1.88 M

B. 1.46 M

C. 0.533 M

D. 0.0848 M

22. The addition of which one of the following compounds would cause

potassium bromide to precipitate from a saturated solution of KBr(aq)?

A. 2

BaI

B. NaCl

C. KOH

D. 4 3

NH NO

- 11 -



Use the following graph showing the solubility curve for selected

solutes to answer questions 23 and NR3.

23. At what temperature will 1 000 g of 3

NaNO produce a saturated

solution?

A. 24 °C

B. 36 °C

C. 45 °C

D. 55 °C

NR3 Given the molar mass of 3KNO is 101.11 g/mol, what is the Ksp for

3KNO at 30 °C? (Round your answer to the nearest whole number.)


sheet.)

- 12 -



24. The following equilibrium was established for a saturated solution of

lead(II) carbonate 3

(PbCO (s)) at 25 °C.

2 2

3 3(s) (aPbCO Pb q ( )CO) aq

If the Ksp value for 3

PbCO (s) is 147.4 10 , what is its solubility?

A. 63.7 10 mol/L

B. 72.7 10 mol/L

C. 143.7 10 mol/L

D. 147.4 10 mol/L

25. Solutions of lead(II) nitrate 3 2)(Pb(NO (s)) and potassium iodide (KI) are

mixed producing the following reaction

3 2 2 3

Pb(NO ) (s) 2 KI(aq) PbI 2 K(? NO) (aq)

After mixing, the 2Pb concentration is 0.050 mol/L and the I

concentration is 0.001 0 mol/L. The Ksp of 2

PbI is 99.8 10 .

What does the value of the trial Ksp indicate?

A. It has a smaller value than the actual Ksp so a precipitate forms.

B. It has a larger value than the actual Ksp so a precipitate will form.

C. It has a larger value than the actual Ksp so a precipitate does not

form.

D. It has a smaller value than the actual Ksp so a precipitate does not

form.

- 13 -



26. Which substance below is considered a base according to the

Brønsted-Lowry theory but not the Arrhenius theory?

A. 4

CH

B. 3

NH

C. NaOH

D. 2

Ca(OH)

27. Which of the following is a conjugate acid-base pair in the reaction

3 2 4NH (g) H O( ) NH (aq) OH (aq) ?

A. H O2 and OH

B. H O2 and NH3

C. H O2 and NH4

D. OH and NH4

28. Acids and bases can be described using the terms strong, weak, dilute

and concentrated. Which statement below is a correct use of the terms?

A. A strong acid cannot be dilute.

B. A weak acid cannot be concentrated.

C. The strength of acids varies during changes in concentration.

D. The strength of acids remains constant during changes in

concentration.

- 14 -



29. Citric acid, symbolized 3

H Ct(aq) , is a triprotic acid that fulfills a variety

of roles. It is used as a food preservative as well as a flavouring agent

for foods, beverages, and confections. It is also used to condition water,

remove sulfur dioxide from smelter waste, and polish metals such as

stainless steel.

Citric acid dissociates through a series of steps:

3 2 3 2H Ct(aq) H O( ) H O (aq) H Ct (aq)

2

2 2 3H Ct (aq) H O( ) H O (aq) HCt (aq)

2 3

2 3HCt (aq) H O( ) H O (aq) Ct (aq)

The Ka values for the three steps in the dissociation, in random order,

are

I 47.0 10

II 66.5 10

III 51.8 10

The Ka values for 3H Ct(aq), 2H Ct (aq), and 2HCt (aq), respectively, are

A. II, I, III

B. II, III, I

C. I, II, III

D. I, III, II

30. What is the ]OH[ 3 in a 0.020 mol/L solution of )aq()OH(Ca 2 ?

A. 121.0 10 mol/L

B. 135.0 10 mol/L

C. 132.5 10 mol/L

D. 141.0 10 mol/L

- 15 -



31. What is the [H ] in a 0.50 mol/L solution of nitrous acid, 2

HNO , which

has a Ka value of 45.1 10 ?

A. 21.6 10 mol/L

B. 31.2 10 mol/L

C. 45.1 10 mol/L

D. 42.6 10 mol/L

32. Litmus works as an acid-base indicator with the following equilibrium

H litmus H litmus

red blue

Referring to the pH ranges of common indicators table, what colour

change would occur when adding 3.0 M NaOH(aq) to a neutral solution

containing litmus?

A. A blue solution turns red.

B. A purple solution turns red.

C. A purple solution turns blue.

D. A blue solution turns purple.

33. An unknown solution is tested with three indicators. The solution is

blue when bromocresol green is added, orange with chlorophenol red,

and yellow when thymol blue is added.

name of indicator colour at acidic

end of range

pH range for

colour change

colour at basic

end of range

bromocresol green yellow 3.8 to 5.4 blue

chlorophenol red yellow 5.2 to 6.8 red

thymol blue yellow 8.0 to 9.6 blue

According to this information, what is the most likely pH of the solution?

A. 3.0

B. 6.0

C. 7.0

D. 8.0

- 16 -



NR4 What volume (in mL) of antacid, 0.015 M 2

Mg(OH) (aq), is required to

neutralize 25 mL of stomach acid, 0.020 M HCl(aq) ? (Round your

answer to the nearest whole number.)


sheet.)

34. An acidic solution was titrated with NaOH(aq) and the data plotted on

the graph shown.

Using the pH Ranges of Common Indicators table supplied with this

examination, the BEST choice of indicator for this titration is

A. orange IV.

B. alizarin yellow.

C. chlorophenol red.

D. phenolphthalein.

- 17 -



35. Which type of reaction is never a redox reaction?

A. synthesis

B. combustion

C. neutralization

D. single replacement

36. A piece of zinc metal heated in the presence of chlorine gas produces

2ZnCl . Which one of the following statements about this

oxidation-reduction process is TRUE?

A. Chlorine is the reducing agent.

B. Zinc metal loses electrons and is oxidized.

C. Zinc metal gains electrons and is reduced.

D. Chlorine gas loses electrons and is oxidized.

37. Which change shows a gain of electrons?

A. 2Ca (aq) toCa(s) .

B. 2Cl (aq) to 2

Cl (g)

C. 2Fe (aq) to 3Fe (aq)

D. NaCl(s) to Na (aq) and Cl (aq)

- 18 -



NR5. Balance the following oxidation-reduction equation.

2

4 2 2 3MnO NO (g) H O Mn NO H

When the coefficient of

4MnO is 1, what are the coefficients of 2

3Mn , NO ,and H ?


sheet.)

38. In an experiment, strips of Au, Bi, Ga, and In were placed in 1.0 M

solutions of 3Au (aq), 3Bi (aq), 3Ga (aq), and 3In (aq). The following

results were observed.

3 3Au Bi Bi Au

3In Bi no reaction 3 3Bi Ga Ga Bi 3 3In Ga Ga In

Using these observations, what is the arrangement of the ions 3Au , 3 In , 3Bi , and 3Ga in decreasing order of their attraction for

electrons?

A. 3 3 3 3Ga , Bi , In , Au

B. 3 3 3 3Ga , In , Bi , Au

C. 3 3 3 3Au , Bi , In , Ga

D. 3 3 3 3Au , In , Bi , Ga

- 19 -



Use the following information to answer questions 39, 40, and 41.

The following diagram represents an electrochemical cell of 2 2Mn(s) Mn (aq) Ni (aq) Ni(s).

39. The substances labelled 2 and 3 could be

A. Ni(s) and 3NiCO (aq)

B. Mn(s) and 3MnCO (aq)

C. Ni(s) and 3 2Ni(NO ) (aq)

D. Mn(s) and 3 2Mn(NO ) (aq)

40. The table indicates the flow of ions and electrons.

Which row in the table is correct?

Direction of Flow of Ions Direction of Flow of Electrons

A. 2Ni flows toward Ni(s) toward Mn(s)

B. 2Ni flows away from Ni(s) toward Mn(s)

C. 2Mn flows away from Mn(s) toward Ni(s)

D. 2Mn flows toward Mn(s) toward Ni(s)

- 20 -



41. The voltage generated by the cell is

A. 2.12 V

B. 0.93 V

C. 1.58 V

D. 3.07 V

______________________________

42. A student made a chart to compare the similarities and differences

between electrochemical and electrolytic cells.

Which line of the chart contains an error?

electrochemical cells electrolytic cells

A. electron flow from anode to

cathode

electron flow from anode to

cathode

B. anode – oxidation

cathode – reduction

anode – oxidation

cathode – reduction

C. anode is negative

cathode is positive

anode is negative

cathode is positive

D. spontaneous – produces

energy

non-spontaneous – requires

energy

43. Which of the following would NOT protect an iron boat against rusting?

A. painting the boat’s hull

B. greasing the boat’s hull

C. sanding the iron surface smooth

D. sending a small electric charge through the iron

- 21 -



44. A sacrificial anode is often connected to the tank of a water heater to

prevent corrosion. If the sacrificial anode prevents the oxidation of iron, 2Fe(s) Fe 2 e , what could the anode be made of?

A. silver

B. nickel

C. copper

D. magnesium

45. Hydrogen fuel cells produce electricity by reacting hydrogen 2

(H ) and

oxygen 2

(O ) gases. A diagram of this process is shown below:

What is the net overall reaction for a hydrogen fuel cell?

A. 2 2 2

2 H (g) O (g) 2 H O(g)

B. 2 2 2

H (g) O (g) 2 H (aq) 2 e 2 H O(g)

C. 2 2 2

H (g) O (g) 4 H (aq) 4 e 2 H (aq) 2 e 2 H O(g)

D. 2 2 2

2 H (g) O (g) 4 H (aq) 4 e 4 H (aq) 4 e 2 H O(g)

MULTIPLE CHOICE

1 11 21 31 41

2 12 22 32 42

3 13 23 33 43

4 14 24 34 44

5 15 25 35 45

6 16 26 36 46

7 17 27 37 47

8 18 28 38 48

9 19 29 39 49

10 20 30 40 50

NUMERIC RESPONSE

NR 1 NR 2 NR 3 NR 4 NR 5

Student Examination Form

Month and Day of Your Birth

JAN Day FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

2 2 2 5 2 5 1 7 1 5 2

Chemistry Prototype2016

- i - DRAFT - Chemistry 30, Prototype Exam - Answer Key

September 2015 – Revised July 2016

GRADE 12 DEPARTMENTAL EXAMINATION

CHEMISTRY 30

PROTOTYPE EXAM — Answer Key

1. D.

The uncertainty principle was first developed in 1927 by Werner Heisenberg.

2. A.

Beryllium is in group 2 on the periodic table so it has 2 valence electrons. Its

electron dot diagram will have 2 dots but not as a pair.

3. B.

Na loses one electron and F gains one electron. All three species have

8 valence electrons.

4. B.

5. C.

Group 3 elements have three valence electrons – Aluminum

6. D.

3NH is trigonal pyramidal 3

(AX E) with 3 bonding pairs and one lone pair of

electrons.

- ii - DRAFT - Chemistry 30, Prototype Exam - Answer Key


7. D.

The weaker the intermolecular forces, the lower the boiling point. 2

Cl has a

non-polar bond and London dispersion forces which are very weak. All of the

other molecules have a polar bond which is a stronger bond.

8. A.

Dispersion force – force generated in non-polar molecules by temporary

dipoles

van der Waals force – weak force of attraction where electrons of one

molecule are attracted to protons of another molecule

Intermolecular force – general term for the force of attraction between any

two molecules

London dispersion force – attractive force between two polar molecules. Also

called dipole-dipole force

9. C.

24 50

C H – organic alkane compound which is a waxy crystal which is quite soft.

Fe – iron, a hard metal

2

SiO – sand, glass

3

CaCO – rocks and shells of marine organisms

NR1 22

An alkane so there will be 2 n + 2 hydrogens. 2(10) + 2 = 22

10. A.

Alkyne – one triple bond

Alkene – one double bond

Alkane – single bonds

Aromatic – three triple bonds in a benzene ring

- iii - DRAFT - Chemistry 30, Prototype Exam - Answer Key


11. D.

- number from the end with the smallest number for an alkyl group

- place alkyl groups in alphabetical order

- name parent chain based on longest continuous chain of carbons - in this

case there are 8 which is hexane

4 – ethyl – 2 – methylhexane

12. B.

All four compounds have the same formula so all of them could be isomers.

Structure B is identical to the original—it has been drawn as a mirror image.

13. A.

Ester is an organic molecule with the functional group:

14. B.

The forward and reverse rates of reaction must be equal.

Keq changes with temperature so cannot be equal at 20 °C and 150 °C.

15. D.

Decreasing pressure has no effect on the value of Keq as there is the same

number of moles of gas on both sides of the equation.

R C

O

O

R

R C

O

O

R

- iv - DRAFT - Chemistry 30, Prototype Exam - Answer Key


62

2 4 2

4 7

3 2

4 72 3 2

2 4 6

2

2 4 7

2 4 6

[N O ] [H O]Keq

[NH ] [O ]

K [NH ] [O ]eq[N O ]

[H O]

(2.16 10 )(2.40) (1.50)[N O ]

1.80

0.60 mol/L

16. A.

Needs to be a shift to the products to increase 2

[NO ]. Only an increase in

temperature will work because the reaction is endothermic (positive ∆H).

17. A.

Y Z X

As the substances change concentration after a stress, Y and Z both decrease

showing that they must be on the same side of the equation. X does the

opposite so must be on the other side of the equation.

18. A.

2[CO ]

Keq[CO]

Solids are not used in Keq expressions and products are always on top.

19. B.

- v - DRAFT - Chemistry 30, Prototype Exam - Answer Key


2

3

3

2 2

2

3

2

2

[NH ]Keq

[N ][H ]

(0.933)0.399

[N ](1.60)

[N ] 0.533M

NR2 25

2H 2

I HI

[initial] 3.0 M 6.0 M 6.0 M

[change] – 2.0 M – 2.0 M + 4.0 M

[equilibrium] 1.0 M 4.0 M 10.0 M

2

2 2

2

[HI]Keq

[H ][I ]

10

(1.0)(4.0)

25

20. C.

Create a stress that will force the equilibrium to the right – an increase in

pressure forces it to 3

SO as there are fewer moles of gas on that side of the

equilibrium.

21. C.

22. C.

Add KOH. The common ion effect occurs when you add a compound which

contains an ion that is in a saturated solution. In this case, both contain K.

23. B.

From the line on the graph for 3NaNO – 1 000 g dissolves at 36 °C.

- vi - DRAFT - Chemistry 30, Prototype Exam - Answer Key


NR3 25

At 30 °C, 500 g of 3

KNO will dissolve in 1.0 L of water.

3 3

1mol500g / Lx 4.95mol / L

101.11g

[KNO ] [K ] [NO ] 4.95M

K (4.95)(4.95)sp

24.5

24. B.

2 2

3

14

7

K [Pb ][CO ]sp

7.4 10 (x)(x)

x 2.7 10

25. B.

The trial 8K (0.050)(0.0010) 5.0 10sp

The trial Ksp is larger than the actual Ksp so a precipitate will form.

26. B.

3

NH – Brønsted-Lowry theory defines a base as a proton (H+) acceptor while

the Arrhenius theory requires the substance to contain and dissociate OH .

27. A.

2

H O and OH – An acid loses one H and creates a conjugate base.

28. D.

Strength and concentration of acids are independent of each other. Strength

will remain constant while concentration is changed.

- vii - DRAFT - Chemistry 30, Prototype Exam - Answer Key


29. D.

The largest Ka value represents the strongest acid. In a dissociation series,

the strongest acid is the original compound and as hydrogens are removed,

the strength of the acids decrease.

4

3

5

2

2 6

H Ct(aq) 7.0 10

H Ct (aq) 1.8 10

HCt (aq) 6.5 10

30. C.

Two OH in the base so OH 0.020 2[ ] 0.040 mol/L

14

14

13

[H ][OH ] 1.0 10 mol/L

1.0 10[H ]

0.040

[H ] 2.5 10 mol/L

31. A.

2 2

2

2

24

2

HNO H NO

[H ][NO ]Ka

[HNO ]

x5.1 10

0.50

x 1.6 10 mol/L

32. C.

A neutral solution would be a purple color. Adding NaOH removes H ions

from the solution shifting the equilibrium to the products, a blue color.

33. B.

The only indicator with a color within the range is chlorophenol red. The

orange color indicates the pH is around the midpoint between 5.2 and 6.8

which is 6.0.

- viii - DRAFT - Chemistry 30, Prototype Exam - Answer Key


NR4 17

There are 2 OH in the base so the formula is MaVa 2 MbVb.

(0.020 M)(25 mL) 2(0.015 M)Vb

Vb = 17 mL

34. D.

The endpoint of the titration is the midway point of the vertical section of the

graph at around 9.0. The only indicator that has this value in its range is

phenolphthalein 8.2–10.0.

35. C.

Neutralization is a special example of a double replacement reaction which

changes ions between two different compounds.

36. B.

A substance that is oxidized will lose electrons. In this reaction, Zn(s) loses

electrons to become 2Zn .

37. A.

Gaining electrons will create a lower charge in the resulting ion/element.

2Ca (aq) gains 2 electrons to create Ca(s).

NR5 152

- ix - DRAFT - Chemistry 30, Prototype Exam - Answer Key


38. C.

Decreasing order means start with the strongest ion.

Reaction 1 shows that 3Au is stronger than 3Bi

Reaction 2 shows that 3Bi is stronger than 3In

Reaction 3 shows that 3Bi is stronger than 3Ga

Reaction 4 shows that 3In is stronger than 3Ga

39. D.

Electrons are leaving the electrode to enter the voltmeter so this is the anode.

Mn is listed lower in the Standard Electrode Potentials table so it is oxidized

in this cell.

A possible electrolyte in the cell must be soluble. 3MnCO is not soluble but

3 2Mn(NO ) is soluble.

40. C.

Mn is the anode so 2Mn ions flow away from it as they are created. Ni is

the cathode in this cell so it will attract 2Ni ions and electrons will travel to

it in the external circuit.

41. B.

Using the Standard Electrode Potentials table in the data booklet,

2

2

2 2

Mn(s) Mn (aq) 2 e 1.18 V

Ni (aq) 2 e Ni(s) 0.25 V

Mn(s) Ni (aq) Mn (aq) Ni(s) 0.93 V

42. C.

Electrolytic cells have the opposite charge on the electrodes. Anode is

positive, cathode is negative.

43. C.

Sanding an iron surface will promote rusting as it exposes more iron to the

atmosphere.

- x - DRAFT - Chemistry 30, Prototype Exam - Answer Key


44. D.

Magnesium is lower than iron in the Standard Electrode Potentials table so it

will corrode before iron.

45. A.

2 2 2

2 H (g) O (g) 2H O(g)

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Grade 12 Prototype Examination Chemistry · Grade 12 Prototype Examination Chemistry Course Code 8256 ... Calculators that have built-in notes ... - 10 - DRAFT - Chemistry 30, Prototype