Question 1

1 mark

An atom of element

X

has exactly

15

protons in its nucleus.

Which of the following statements correctly describes the position of

X

in the Periodic Table or its electron configuration?

A.It is in Period $5$ and Group $3$ .
B.It is in Period $3$ and its atoms have the electron configuration $2, 8, 5$ .
C.It is in Period $3$ and Group $5$ .
D.It is in Group $15$ and its atoms have three electron shells that are all completely full.
E.It is in Group $15$ and has the same number of occupied electron shells as an atom of nitrogen.

Answer: B

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Question 2

1 mark

Consider four elements,

E_1

,

E_2

,

E_3

, and

E_4

, based on their positions in the Periodic Table:
-

E_1

is in Group 2, Period 2.
-

E_2

is in Group 2, Period 3.
-

E_3

is in Group 17, Period 2.
-

E_4

is in Group 17, Period 3.

Which of the following correctly compares the chemical reactivity within each pair and provides the correct physical justification?

A. $E_2$ is more reactive than $E_1$ , and $E_3$ is more reactive than $E_4$ . Reasoning: In metals, a larger atomic radius increases reactivity; in non-metals, a smaller atomic radius increases reactivity.
B. $E_1$ is more reactive than $E_2$ , and $E_4$ is more reactive than $E_3$ . Reasoning: Reactivity is determined primarily by the number of electron shells, with more shells always resulting in higher reactivity.
C. $E_2$ is more reactive than $E_1$ , and $E_3$ is more reactive than $E_4$ . Reasoning: Reactivity increases as the total nuclear charge of the atom increases.
D. $E_1$ is more reactive than $E_2$ , and $E_3$ is more reactive than $E_4$ . Reasoning: Reactivity decreases down every group of the Periodic Table because shielding increases.
E. $E_2$ is more reactive than $E_1$ , and $E_4$ is more reactive than $E_3$ . Reasoning: Reactivity increases down every group of the Periodic Table as the first ionisation energy decreases.

Answer: A

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Question 3

1 mark

A sample of

0.70\,\text{g}

of pure lithium-7 (

^7\text{Li}

) is reacted completely with an excess of chlorine-37 gas (

^{37}\text{Cl}_2

) to form lithium chloride (

^7\text{Li}^{37}\text{Cl}

). Given that the atomic numbers (

Z

) of lithium and chlorine are

3

and

17

respectively, and the Avogadro constant

N_A = 6.0 \times 10^{23}\,\text{mol}^{-1}

, what is the total number of neutrons in the nuclei of the product formed?

A.7.2 $\times$ 10^{23}
B.1.20 $\times$ 10^{24}
C.1.32 $\times$ 10^{24}
D.1.44 $\times$ 10^{24}
E.2.40 $\times$ 10^{24}

Answer: D

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Question 4

1 mark

A sample of a metal phosphate is analysed and found to contain the following number of atoms:

-

4.5 \times 10^{23}

atoms of metal

M

-

3.0 \times 10^{23}

atoms of phosphorus
-

1.2 \times 10^{24}

atoms of oxygen

What is the simplest formula for the nitride of metal

M

?

(Take the Avogadro constant to be

L = 6.0 \times 10^{23}\,\text{mol}^{-1}

)

A. $MN$
B. $M_3N$
C. $M_3N_2$
D. $M_2N_3$
E. $M_3N_4$

Answer: C

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Question 5

1 mark

A small sample of solid sodium hydrogencarbonate (

\text{NaHCO}_3

) is added to a beaker containing an excess of dilute sulfuric acid (

\text{H}_2\text{SO}_4

) at

25^\circ\text{C}

and

100\,\text{kPa}

. A vigorous effervescence is observed as a gas is evolved, and the solid disappears to leave a clear, colourless solution. Which of the following is the correctly balanced chemical equation for this reaction, including state symbols?

A. $2\text{NaHCO}_3(\text{s}) + \text{H}_2\text{SO}_4(\text{aq}) \rightarrow \text{Na}_2\text{SO}_4(\text{aq}) + 2\text{H}_2\text{O}(\text{l}) + 2\text{CO}_2(\text{g})$
B. $\text{NaHCO}_3(\text{s}) + \text{H}_2\text{SO}_4(\text{aq}) \rightarrow \text{NaSO}_4(\text{aq}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g})$
C. $2\text{NaHCO}_3(\text{aq}) + \text{H}_2\text{SO}_4(\text{aq}) \rightarrow \text{Na}_2\text{SO}_4(\text{aq}) + 2\text{H}_2\text{O}(\text{l}) + 2\text{CO}_2(\text{g})$
D. $2\text{NaHCO}_3(\text{s}) + \text{H}_2\text{SO}_4(\text{aq}) \rightarrow \text{Na}_2\text{SO}_4(\text{s}) + 2\text{H}_2\text{O}(\text{l}) + 2\text{CO}_2(\text{g})$
E. $2\text{NaHCO}_3(\text{s}) + \text{H}_2\text{SO}_4(\text{aq}) \rightarrow \text{Na}_2\text{SO}_4(\text{aq}) + 2\text{H}_2\text{O}(\text{aq}) + 2\text{CO}_2(\text{g})$

Answer: A

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Question 6

1 mark

The reaction between calcium hydroxide and phosphoric acid is represented by the following unbalanced chemical equation:

x\text{Ca}(\text{OH})_2 + y\text{H}_3\text{PO}_4 \rightarrow z\text{Ca}_3(\text{PO}_4)_2 + w\text{H}_2\text{O}

What is the value of the sum

x + y + z + w

when the equation is balanced using the simplest possible whole-number coefficients?

A.8
B.9
C.10
D.11
E.12

Answer: E

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Question 7

1 mark

Consider the following two independent reversible gas-phase reactions at equilibrium in separate closed containers:

Reaction 1:

\text{N}_2(\text{g}) + 3\text{H}_2(\text{g}) \rightleftharpoons 2\text{NH}_3(\text{g})

\Delta H = -92\,\text{kJ}\,\text{mol}^{-1}

Reaction 2:

\text{CO}(\text{g}) + \text{H}_2\text{O}(\text{g}) \rightleftharpoons \text{CO}_2(\text{g}) + \text{H}_2(\text{g})

\Delta H = -41\,\text{kJ}\,\text{mol}^{-1}

Which of the following independent changes, assuming all other conditions remain constant, will increase the initial rate of reaction and increase the equilibrium yield of products for Reaction 1, but will increase the initial rate of reaction without changing the equilibrium yield of products for Reaction 2?

A.Adding a suitable catalyst
B.Increasing the temperature
C.Decreasing the volume of the container
D.Increasing the volume of the container
E.Adding more of a reactant ( $\text{N}_2$ to Reaction 1 and $\text{CO}$ to Reaction 2)

Answer: C

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Question 8

1 mark

Titanium is extracted from titanium(IV) chloride by reaction with magnesium according to the following balanced equation:

TiCl_4 + 2Mg \rightarrow Ti + 2MgCl_2

What mass of titanium is produced when

1.9

tonnes of

TiCl_4

is reacted with an excess of magnesium?

(Assume the reaction goes to completion.

A_r

values:

Mg = 24

;

Cl = 35.5

;

Ti = 48

.

1

tonne

= 1000

kg)

A. $48$ kg
B. $240$ kg
C. $480$ kg
D. $960$ kg
E. $1900$ kg

Answer: C

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Question 9

1 mark

A mixture of

5.6 \text{ g}

of iron and

4.0 \text{ g}

of sulfur is heated to form iron(II) sulfide according to the following equation:

\text{Fe}(\text{s}) + \text{S}(\text{s}) \rightarrow \text{FeS}(\text{s})

What is the maximum mass of iron(II) sulfide that can be produced?
(

A_r

values:

\text{Fe} = 56

;

\text{S} = 32

)

A. $4.0 \text{ g}$
B. $5.6 \text{ g}$
C. $8.8 \text{ g}$
D. $9.6 \text{ g}$
E. $11.0 \text{ g}$

Answer: C

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Question 10

1 mark

A sample of

2.24\,\text{g}

of a metal

M

(relative atomic mass

A_r = 56

) reacts completely with an excess of dilute hydrochloric acid to produce

960\,\text{cm}^3

of hydrogen gas.

A second sample of the same metal

M

, with a mass of

3.36\,\text{g}

, is heated in an excess of oxygen to produce

4.80\,\text{g}

of a metal oxide.

Which of the following is the correctly balanced equation for the reaction of this metal oxide with dilute phosphoric acid,

H_3PO_4

?

(Assume that

1\,\text{mol}

of gas occupies

24\,\text{dm}^3

at room temperature and pressure.)

A. $3MO + 2H_3PO_4 \rightarrow M_3(PO_4)_2 + 3H_2O$
B. $M_2O_3 + 3H_3PO_4 \rightarrow M_2(PO_4)_3 + 3H_2O$
C. $M_2O_3 + 2H_3PO_4 \rightarrow 2MPO_4 + 3H_2O$
D. $3M_2O + 2H_3PO_4 \rightarrow 2M_3PO_4 + 3H_2O$
E. $3MO_2 + 4H_3PO_4 \rightarrow M_3(PO_4)_4 + 6H_2O$

Answer: C

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Question 11

1 mark

A

1.00\text{ g}

sample of limestone contains

50.0\%

calcium carbonate by mass. The limestone reacts with an excess of dilute hydrochloric acid according to the following equation:

\text{CaCO}_3(\text{s}) + 2\text{HCl}(\text{aq}) \rightarrow \text{CaCl}_2(\text{aq}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g})

What is the volume of carbon dioxide gas produced when measured at room temperature and pressure (rtp)?

(

A_r

values:

\text{C} = 12

;

\text{O} = 16

;

\text{Ca} = 40

. Assume that one mole of gas occupies

24.0\text{ dm}^3

at rtp.)

A. $12\text{ cm}^3$
B. $120\text{ cm}^3$
C. $240\text{ cm}^3$
D. $480\text{ cm}^3$
E. $1200\text{ cm}^3$

Answer: B

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Question 12

1 mark

A student prepares a saturated solution of an anhydrous salt

Z

(

M_{\text{r}} = 150

) by dissolving it in

200\,\text{g}

of water at

80\,^\circ\text{C}

. The solubility of

Z

at

80\,^\circ\text{C}

is

60\,\text{g}

per

100\,\text{g}

of water. At

25\,^\circ\text{C}

, the solubility of

Z

is

15\,\text{g}

per

100\,\text{g}

of water.

The solution is cooled to

25\,^\circ\text{C}

and the resulting crystals of

Z

are removed by filtration. Distilled water is then added to the remaining solution until the total volume is

500\,\text{cm}^3

.

What is the concentration, in

\text{mol dm}^{-3}

, of

Z

in the final solution?

A.0.20 mol dm⁻³
B.0.40 mol dm⁻³
C.0.80 mol dm⁻³
D.1.20 mol dm⁻³
E.1.60 mol dm⁻³

Answer: B

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Question 13

1 mark

In which of the following reactions is the underlined species being reduced?

A. $\underline{\text{Zn}(\text{s})} + \text{CuSO}_4(\text{aq}) \rightarrow \text{ZnSO}_4(\text{aq}) + \text{Cu}(\text{s})$
B. $\underline{\text{Cu}^{2+}(\text{aq})} + \text{Mg}(\text{s}) \rightarrow \text{Cu}(\text{s}) + \text{Mg}^{2+}(\text{aq})$
C. $2\underline{\text{Br}^-(\text{aq})} + \text{Cl}_2(\text{g}) \rightarrow \text{Br}_2(\text{l}) + 2\text{Cl}^-(\text{aq})$
D. $\underline{\text{Sn}^{2+}(\text{aq})} + 2\text{Fe}^{3+}(\text{aq}) \rightarrow \text{Sn}^{4+}(\text{aq}) + 2\text{Fe}^{2+}(\text{aq})$
E. $\underline{\text{Mg}(\text{s})} + 2\text{HCl}(\text{aq}) \rightarrow \text{MgCl}_2(\text{aq}) + \text{H}_2(\text{g})$

Answer: B

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Question 14

1 mark

The thiosulfate ion (

S_2O_3^{2-}

) can be oxidized by different halogen reagents.

In Reaction 1,

S_2O_3^{2-}

reacts with iodine (

I_2

) to form the tetrathionate ion (

S_4O_6^{2-}

).
In Reaction 2,

S_2O_3^{2-}

reacts with chlorine (

Cl_2

) in aqueous solution to form the hydrogensulfate ion (

HSO_4^-

).

Let

x

be the increase in the average oxidation state of the sulfur atoms in Reaction 1.
Let

y

be the increase in the average oxidation state of the sulfur atoms in Reaction 2.

What is the value of the ratio

\frac{y}{x}

?

A.2
B.4
C.6
D.8
E.16

Answer: D

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Question 15

1 mark

The manganate(VI) ion,

MnO_4^{2-}

, is stable in strongly alkaline solutions but undergoes disproportionation when the solution is acidified. The products of this reaction are the manganate(VII) ion,

MnO_4^-

, and manganese(IV) oxide,

MnO_2

.

The unbalanced ionic equation for this reaction is:

xMnO_4^{2-} + yH^+ ightarrow zMnO_4^- + vMnO_2 + wH_2O

In the simplest balanced equation using whole-number coefficients, what is the ratio of the sum of the reactant coefficients

(x + y)

to the sum of the product coefficients

(z + v + w)

?

A.1:1
B.3:2
C.7:4
D.7:5
E.5:7

Answer: D

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Question 16

1 mark

In which two of the following equations is the **first reactant** acting as a **reducing agent**?

1

3CO + Fe_2O_3 \rightarrow 3CO_2 + 2Fe

2

16HCl + 2KMnO_4 \rightarrow 5Cl_2 + 2MnCl_2 + 2KCl + 8H_2O

3

H_2O_2 + 2HI \rightarrow 2H_2O + I_2

4

4HNO_3 + Cu \rightarrow 2NO_2 + Cu(NO_3)_2 + 2H_2O

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

Answer: A

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Question 17

1 mark

Consider the following observations for three substances,

X

,

Y

, and

Z

:

- Substance

X

: A solid with a constant melting point. When heated in a vacuum, it sublimes; the resulting gas consists of molecules, each containing four atoms of the same atomic number.
- Substance

Y

: A liquid with a constant boiling point. When an electric current is passed through it, the substance is entirely consumed to produce only two different gases in a fixed mass ratio of

1:8

.
- Substance

Z

: A liquid with a constant boiling point. When the external pressure is significantly reduced and the liquid is distilled, the density of the first

10\,\text{cm}^3

of distillate is found to be different from the density of the original liquid.

Which of the following correctly classifies

X

,

Y

, and

Z

?

A. $X$ is an element; $Y$ is a compound; $Z$ is a mixture.
B. $X$ is a compound; $Y$ is a compound; $Z$ is a mixture.
C. $X$ is an element; $Y$ is a mixture; $Z$ is a mixture.
D. $X$ is an element; $Y$ is a compound; $Z$ is a compound.
E. $X$ is a compound; $Y$ is a mixture; $Z$ is a compound.

Answer: A

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Question 18

1 mark

Three elements,

X, Y,

and

Z,

are described by their positions in the Periodic Table:

- Element

X

is in Period 3, Group 2.
- Element

Y

is in Period 2, Group 15.
- Element

Z

is in Period 3, Group 17.

Which of the following statements about these elements is/are correct?

1.

X

and

Y

react to form an ionic compound with the formula

X_3Y_2

.
2. The compound formed between

Y

and

Z

has a simple molecular structure.
3. In the compound formed between

X

and

Z,

both the cation and the anion have the same electron configuration as an atom of argon.

A.1 only
B.2 only
C.1 and 2 only
D.2 and 3 only
E.1, 2 and 3

Answer: C

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Question 19

1 mark

Element

X

has atomic number 12 and element

Y

has atomic number 17. Which of the following correctly identifies the formula of the compound formed between

X

and

Y

and its electrical conductivity in the states specified?

A.formula: $XY$ ; electrical conductivity: conducts when solid and when liquid
B.formula: $X_2Y$ ; electrical conductivity: conducts when liquid but not when solid
C.formula: $XY_2$ ; electrical conductivity: conducts when solid and when liquid
D.formula: $XY_2$ ; electrical conductivity: conducts when liquid but not when solid
E.formula: $XY_2$ ; electrical conductivity: does not conduct when solid or when liquid

Answer: D

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Question 20

1 mark

Which of the following statements is/are correct?

1. The dioxide of the element in Period 3, Group 14 has a higher melting point than the dioxide of the element in Period 2, Group 14.

2. A molecule of the dioxide of the element in Period 2, Group 14 contains the same number of shared pairs of electrons as a molecule of the element in Period 2, Group 15.

3. The element in Period 2, Group 14 has an allotrope with a giant covalent structure in which each atom is covalently bonded to exactly three other atoms.

A.1 only
B.2 only
C.1 and 2 only
D.1 and 3 only
E.1, 2 and 3

Answer: D

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Question 21

1 mark

Consider the Period 3 metals sodium (

Na

, atomic number 11), magnesium (

Mg

, atomic number 12), and aluminium (

Al

, atomic number 13). Which of the following options correctly describes the trend in the number of delocalised electrons provided per atom and the relative melting points of these metals in their solid states?

A.Number of delocalised electrons: $Na < Mg < Al$ ; Melting point: $Na < Mg < Al$
B.Number of delocalised electrons: $Na < Mg < Al$ ; Melting point: $Al < Mg < Na$
C.Number of delocalised electrons: $Na > Mg > Al$ ; Melting point: $Na > Mg < Al$
D.Number of delocalised electrons: $Na = Mg = Al$ ; Melting point: $Na < Mg < Al$
E.Number of delocalised electrons: $Na < Mg < Al$ ; Melting point: $Na = Mg = Al$

Answer: A

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Question 22

1 mark

The boiling points of three substances, each of which contains 18 electrons per molecule, are given below:

- Ethane (

C_2H_6

):

-89

°C
- Fluoromethane (

CH_3F

):

-78

°C
- Methanol (

CH_3OH

):

65

°C

Which of the following statements correctly explain(s) these observations?

1. Methanol has the highest boiling point because

O-H

covalent bonds are stronger than

C-H

or

C-F

covalent bonds and require more energy to break during boiling.
2. Fluoromethane has a higher boiling point than ethane because fluoromethane molecules experience permanent dipole-dipole interactions, whereas ethane molecules only experience London dispersion forces.
3. The differences in boiling points are due to the different strengths of the intermolecular forces that must be overcome during the change of state.

A.1 only
B.2 only
C.3 only
D.1 and 2 only
E.2 and 3 only

Answer: E

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Question 23

1 mark

Which of the following statements about the halogens in Group 17 is/are correct?

1. The boiling point of the elements increases as the atomic number increases.
2. Bromine will oxidise chloride ions in an aqueous solution of sodium chloride.
3. Iodine is a solid at room temperature and pressure.

A.1 only
B.3 only
C.1 and 2 only
D.1 and 3 only
E.1, 2 and 3

Answer: D

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Question 24

1 mark

A student is provided with a solid mixture containing

11.7\,\text{g}

of sodium chloride (

\text{NaCl}

) and

16.0\,\text{g}

of iron(III) oxide (

\text{Fe}_2\text{O}_3

). They are tasked with using appropriate chemical processes to obtain pure samples of chlorine gas (

\text{Cl}_2

) and metallic iron (

\text{Fe}

).

Assume

100\%

yield for all chemical reactions and that all atomic masses are exact:

A_r(\text{Na}) = 23.0

,

A_r(\text{Cl}) = 35.5

,

A_r(\text{Fe}) = 56.0

,

A_r(\text{O}) = 16.0

.

What is the maximum total mass of chlorine gas and iron metal that can be extracted from this mixture?

A. $12.7\,\text{g}$
B. $15.8\,\text{g}$
C. $18.3\,\text{g}$
D. $25.4\,\text{g}$
E. $27.7\,\text{g}$

Answer: C

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Question 25

1 mark

A technician needs to separate a mixture of three substances:

P

,

Q

, and

R

. The properties of these substances are provided in the table below:

| substance |

P

|

Q

|

R

|
| :--- | :--- | :--- | :--- |
| state at

25\,^\circ\text{C}

^\circ\text{C}

|

450

|

68

|

97

|

Substance

P

is insoluble in both

Q

and

R

, whereas liquids

Q

and

R

are miscible. Which of the following procedures is most suitable to obtain a pure sample of liquid

Q

?

A.Filter the mixture to remove $P$ , then use a separating funnel to separate $Q$ and $R$ .
B.Filter the mixture to remove $P$ , then distil the filtrate and collect the fraction at $68\,^\circ\text{C}$ .
C.Filter the mixture to remove $P$ , then distil the filtrate and collect the fraction at $97\,^\circ\text{C}$ .
D.Use a separating funnel to remove $P$ from the mixture, then distil the remaining liquids and collect the fraction at $68\,^\circ\text{C}$ .
E.Distil the mixture and collect the fraction at $68\,^\circ\text{C}$ , then filter the distillate to remove any $P$ .

Answer: B

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Question 26

1 mark

A student used paper chromatography to investigate three unknown liquid samples,

X

,

Y

, and

Z

, alongside a pure standard

S

. After the solvent front had moved

12.0\,\text{cm}

from the baseline, the following distances from the baseline were recorded for the observed spots:

- Pure standard

S

: one spot at

9.0\,\text{cm}

- Sample

X

: two spots at

6.0\,\text{cm}

and

9.0\,\text{cm}

- Sample

Y

: one spot at

3.0\,\text{cm}

- Sample

Z

: one spot at

9.0\,\text{cm}

Which of the following statements is/are correct?

1. The chromatogram indicates that Sample

X

is a mixture containing substance

S

.
2. The

R_f

value of the substance in Sample

Y

is

0.25

.
3. The substance in Sample

S

has a higher affinity for the stationary phase than the substance in Sample

Y

.

A.1 only
B.1 and 2 only
C.1 and 3 only
D.2 and 3 only
E.1, 2 and 3

Answer: B

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Question 27

1 mark

Two solutions are prepared at

25^\circ\text{C}

:

Solution X:

100\,\text{cm}^3

of

0.0050\,\text{mol dm}^{-3}

sulfuric acid (

H_2SO_4

), which is a strong diprotic acid.

Solution Y:

100\,\text{cm}^3

of a weak monoprotic acid (

HB

) which has the same pH as solution X.

Consider the following three statements:

1. The pH of solution X is

2.0

.

2. To reach the end-point of a titration, solution Y requires a greater amount (in moles) of sodium hydroxide than solution X.

3. When excess magnesium ribbon is added to solution X,

24\,\text{cm}^3

of hydrogen gas is produced, measured at room temperature and pressure.

(Assume the molar volume of a gas at room temperature and pressure is

24.0\,\text{dm}^3\,\text{mol}^{-1}

).

Which of the statements is/are correct?

A.1 only
B.2 only
C.1 and 2 only
D.2 and 3 only
E.1, 2 and 3

Answer: C

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Question 28

1 mark

A

0.56\text{ g}

sample of calcium oxide (

CaO

) is added to

2.0\text{ dm}^3

of distilled water. The calcium oxide reacts completely to form a solution of calcium hydroxide (

Ca(OH)_2

).

Assume that the final volume of the solution is

2.0\text{ dm}^3

and that calcium hydroxide is a strong base that dissociates completely.

Which of the following statements about this process and the resulting solution is correct?

(

A_r

values:

H = 1, O = 16, Ca = 40

;

\log_{10} 2 \approx 0.30

)

A.The concentration of $OH^-(aq)$ ions in the solution is $0.005\text{ mol dm}^{-3}$ .
B.The $pH$ of the final solution is $12.3$ .
C.The $pH$ of the final solution is $12.0$ .
D.Calcium hydroxide is a weak base because it is in a dilute solution.
E.Calcium oxide acts as a Brønsted-Lowry acid in its reaction with water.

Answer: C

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Question 29

1 mark

Three experiments are carried out to investigate the temperature change during the neutralisation of hydrochloric acid,

\text{HCl}(aq)

, and sodium hydroxide,

\text{NaOH}(aq)

.

In each experiment, the initial temperature of both solutions is

20.0^\circ\text{C}

. The solutions are mixed in an insulated polystyrene cup and stirred.

Experiment 1:

50\,\text{cm}^3

of

1.0\,\text{mol dm}^{-3}

\text{HCl}

is added to

50\,\text{cm}^3

of

1.0\,\text{mol dm}^{-3}

\text{NaOH}

.

Experiment 2:

100\,\text{cm}^3

of

1.0\,\text{mol dm}^{-3}

\text{HCl}

is added to

100\,\text{cm}^3

of

1.0\,\text{mol dm}^{-3}

\text{NaOH}

.

Experiment 3:

50\,\text{cm}^3

of

2.0\,\text{mol dm}^{-3}

\text{HCl}

is added to

50\,\text{cm}^3

of

2.0\,\text{mol dm}^{-3}

\text{NaOH}

.

Which of the following correctly compares the maximum temperatures (

T_{\text{max}}

) reached in these experiments? (Assume that the density and specific heat capacity are the same for all solutions, and there is no heat loss to the surroundings.)

A. $T_{\text{max}}(\text{Exp 1}) < T_{\text{max}}(\text{Exp 2}) < T_{\text{max}}(\text{Exp 3})$
B. $T_{\text{max}}(\text{Exp 1}) = T_{\text{max}}(\text{Exp 2}) = T_{\text{max}}(\text{Exp 3})$
C. $T_{\text{max}}(\text{Exp 1}) = T_{\text{max}}(\text{Exp 2}) < T_{\text{max}}(\text{Exp 3})$
D. $T_{\text{max}}(\text{Exp 1}) < T_{\text{max}}(\text{Exp 2}) = T_{\text{max}}(\text{Exp 3})$
E. $T_{\text{max}}(\text{Exp 2}) < T_{\text{max}}(\text{Exp 1}) = T_{\text{max}}(\text{Exp 3})$

Answer: C

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Question 30

1 mark

Calcium carbonate reacts with hydrochloric acid according to the following equation:

\text{CaCO}_3(\text{s}) + 2\text{HCl}(\text{aq}) \rightarrow \text{CaCl}_2(\text{aq}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g})

In a reference experiment,

1.00\,\text{g}

of calcium carbonate chips (a few large pieces) is added to

100\,\text{cm}^3

of

1.0\,\text{mol\,dm}^{-3}

hydrochloric acid at

25\,^\circ\text{C}

. The volume of carbon dioxide gas produced is monitored over time, and the result is plotted as line P on a graph.

Which of the following experiments, performed with the same apparatus, would produce a curve that has a steeper initial gradient than line P, but levels off at exactly half the final volume of line P?

(

A_r

values:

\text{Ca} = 40.0, \text{C} = 12.0, \text{O} = 16.0

. Assume that the volume of one mole of gas is

24.0\,\text{dm}^3

at the temperature and pressure of the laboratory.)

A. $0.50\,\text{g}$ of identical calcium carbonate chips and $100\,\text{cm}^3$ of $1.0\,\text{mol\,dm}^{-3}$ hydrochloric acid at $25\,^\circ\text{C}$ .
B. $1.00\,\text{g}$ of identical calcium carbonate chips and $100\,\text{cm}^3$ of $0.1\,\text{mol\,dm}^{-3}$ hydrochloric acid at $25\,^\circ\text{C}$ .
C. $0.50\,\text{g}$ of calcium carbonate powder and $100\,\text{cm}^3$ of $1.0\,\text{mol\,dm}^{-3}$ hydrochloric acid at $25\,^\circ\text{C}$ .
D. $1.00\,\text{g}$ of identical calcium carbonate chips and $50\,\text{cm}^3$ of $2.0\,\text{mol\,dm}^{-3}$ hydrochloric acid at $25\,^\circ\text{C}$ .
E. $0.50\,\text{g}$ of identical calcium carbonate chips and $100\,\text{cm}^3$ of $1.0\,\text{mol\,dm}^{-3}$ hydrochloric acid at $40\,^\circ\text{C}$ .

Answer: C

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ESAT Mock Chemistry Esat-chem-bank-3

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