Matter And the Particle Model — Free IB MYP4 Chemistry Questions

1QuestionDensity differences between statesConcept Practice

4 marks~6 minCriterion B

The diagrams below show the same number of particles in a fixed volume for three states of matter: solid, liquid, and gas. The particles are represented as circles, and the volume is the same in all three diagrams.

Diagram 1 (Solid): Particles are arranged in a regular, closely packed pattern with minimal space between them.
Diagram 2 (Liquid): Particles are arranged randomly but still relatively close together, with some small gaps between them.
Diagram 3 (Gas): Particles are spread far apart with large gaps between them, moving freely.

a

Describe the pattern you observe in the spacing between particles from solid to liquid to gas.

b

Based on this pattern, deduce the order of density (highest to lowest) for the three states.

c

Justify your deduction by explaining how particle arrangement relates to mass per unit volume.

Solutions

2QuestionReal-life examples and state identificationConcept Practice

3 marks~5 minCriterion A

The diagram shows a beaker containing ice cubes floating in liquid water, with steam rising above the water surface. Three regions are labelled: X (ice cubes), Y (liquid water), and Z (steam).

a

State the state of matter represented by each labelled region, X, Y, and Z. [1]

b

Identify one visible property shown in the diagram that distinguishes region X (solid) from region Y (liquid). [1]

c

Explain why region Z behaves differently from regions X and Y in terms of particle arrangement and movement. [1]

Solutions

3QuestionExplaining macroscopic properties using particle theoryConcept Practice

2 marks~3 minCriterion A

The diagram shows particles arranged in a regular, tightly packed lattice with negligible spaces between them.

a

Identify the state of matter shown in the diagram. [1]

b

Explain one macroscopic property of this state of matter using the particle arrangement shown. [1]

Solutions

4QuestionSpacing and forces between particlesConcept Practice

4 marks~6 minCriterion B

The heating curve below shows temperature vs. time for a 100 g sample of substance X being heated at a constant rate. The curve has two plateaus: one at 0°C (melting) and one at 100°C (boiling).

Temperature (°C): -10 → 0 (plateau) → 20 → 100 (plateau) → 110
Time (min): 0 → 2 → 4 → 6 → 8 → 10

a

During the plateaus, what happens to the spacing between particles and the forces between them? Explain briefly.

b

Predict how the heating curve would differ for a 100 g sample of substance Y, which has a higher specific heat capacity than X but the same melting and boiling points. Justify your prediction by referring to energy, spacing, and forces.

Solutions

5QuestionInterpreting heating and cooling graphsConcept Practice

3 marks~5 minCriterion A

The heating curve for water shows temperature (vertical axis) against time (horizontal axis). Five segments are labelled: A (solid ice warming), B (melting at

0^\circ\text{C}

), C (liquid water warming), D (boiling at

100^\circ\text{C}

), and E (steam warming).

a

Identify which segment represents the melting point of water. [1]

b

Explain why temperature remains constant during segment B, even though heat is continuously supplied. In your answer, refer to particle behaviour and how the energy is used. [2]

Solutions

6QuestionExamples of diffusion (perfume spreading, gas exchange)Concept Practice

3 marks~5 minCriterion B

An open perfume bottle is placed in a room. The rate at which the perfume vapour spreads is measured at three temperatures.

Temperature (°C)	20	30	40
Rate of diffusion (arbitrary units)	2.0	3.5	5.5

a

Identify the trend shown by the data. [1]

b

Using particle theory, explain why increasing temperature affects the speed of perfume molecules. [1]

c

Analyse why faster-moving perfume molecules produce a higher rate of diffusion through air. [1]

Solutions

7QuestionExamples of diffusion (perfume spreading, gas exchange)Concept Practice

4 marks~6 minCriterion A

The diagram shows an alveolus in contact with a surrounding capillary. The alveolus contains a high concentration of

O_2

molecules; the capillary blood contains a high concentration of

CO_2

molecules and a low concentration of

O_2

molecules.

a

State the direction of net movement of

O_2

molecules. [1]

b

Deduce the direction of net movement of

CO_2

molecules, and identify the driving force responsible. [1]

c

Explain, using particle theory, why

O_2

moves from the alveolus into the blood rather than in the opposite direction. [2]

Solutions

8QuestionReversible vs irreversible changesConcept Practice

2 marks~3 minCriterion A

When hydrated copper(II) sulfate is heated, it loses water of crystallisation to form anhydrous copper(II) sulfate. This is a reversible reaction: adding water to the anhydrous solid reforms the hydrated salt.

a

State the colour change observed when hydrated copper(II) sulfate is heated, and identify what type of change this represents. [1]

b

Construct the balanced chemical equation, with state symbols, for the forward reaction only. [1]

Solutions

9QuestionDensity differences between statesAssessment Practice

6 marks~9 minCriterion D

A chemical spill releases 5000 L of an organic solvent (density

1.5\ \text{g/cm}^3

) into a freshwater lake (density

1.0\ \text{g/cm}^3

). The solvent is immiscible with water.

(a) Deduce where the solvent will settle in the lake, using the density values given. [1]

(b) Explain the environmental impacts of this spill on:

(i) benthic organisms living on the lakebed. [2]

(ii) surface-dwelling fish and birds. [2]

(c) Evaluate the reliability of using density alone to predict the long-term distribution of the solvent in the lake. [1]

Solutions

10QuestionParticle arrangement in each stateAssessment Practice

5 marks~8 minCriterion C

A student investigates diffusion by placing a drop of the same coloured dye, at the same temperature, into three media. The time for the dye to travel 2 cm is recorded.

Medium: solid agar gel	liquid water	air
Time (min): 120	30	2

a

Describe the arrangement and spacing of particles in solids, liquids, and gases. [2]

b

Explain how the particle arrangement in each medium accounts for the diffusion times recorded above. [2]

c

Evaluate the hypothesis: "Particle spacing is the sole factor determining the speed of diffusion." In your response, assess whether the data fully support this claim and identify one additional factor that influences diffusion rate, explaining how it does so. [1]

Solutions

11QuestionParticle motion in solids, liquids, and gasesAssessment Practice

3 marks~5 minCriterion C

The graph below shows the volume of

H_2

gas produced over time when magnesium ribbon reacts with excess hydrochloric acid at three temperatures: 20°C, 30°C, and 40°C. All three curves reach a final volume of 60 cm³, but the reaction completes at 120 s, 80 s, and 50 s respectively.

a

State what the graph shows about how increasing temperature affects the rate of reaction. [1]

b

Using the particle model, explain why increasing temperature produces this effect. [1]

c

All three reactions produce exactly 60 cm³ of

H_2

. Analyse what this tells you about the amount of magnesium used, and explain why temperature alone cannot change this outcome. [1]

Solutions

12QuestionExplaining macroscopic properties using particle theoryAssessment Practice

5 marks~8 minCriterion D

At sea level (

0 \, \text{m}

), atmospheric pressure is

101.3 \, \text{kPa}

and water boils at

100°\text{C}

. At

3000 \, \text{m}

, pressure falls to

70.0 \, \text{kPa}

and water boils at

95°\text{C}

.

Altitude (m)	0	1000	2000	3000	4000	5000
Atmospheric pressure (kPa)	101.3	89.9	79.5	70.0	61.6	54.0

a

Explain what must happen at the particle level for water to boil. [1]

b

Explain how the data show that atmospheric pressure affects the boiling point of water. [2]

c

A mountaineer claims that food cooked in boiling water at

5000 \, \text{m}

will take longer to cook than at sea level. Evaluate this claim using particle theory and the data provided. [2]

Solutions

13QuestionEnergy transfer during state changes (heating/cooling curves)Assessment Practice

5 marks~8 minCriterion B

A group of students heats separate 10 g samples of stearic acid from

20^\circ\text{C}

to

80^\circ\text{C}

at three different rates, recording temperature every 30 seconds.

Heating rate ( $^\circ\text{C min}^{-1}$ )	0.5	1.0	2.0
Plateau duration (min)	8.0	4.0	2.0

a

Deduce the relationship between heating rate and plateau duration. [1]

b

Justify a prediction for the plateau duration at a heating rate of

4.0^\circ\text{C min}^{-1}

. [2]

c

Analyse how the fixed latent heat of fusion of stearic acid accounts for the plateau durations observed at different heating rates. [2]

Solutions

14QuestionConstant temperature during phase changesAssessment Practice

6 marks~9 minCriterion D

A community thermal battery uses paraffin wax as a phase-change material (PCM) to store solar heat. The wax melts at a constant temperature of

47^\circ\text{C}

during the day, storing energy, and solidifies at night, releasing heat to replace natural gas for domestic heating. Paraffin wax is petroleum-derived; its production releases volatile organic compounds (VOCs) into the local atmosphere.

a

Explain why the temperature remains constant at

47^\circ\text{C}

while the paraffin wax is melting. [2]

b

Analyse the environmental trade-off between reduced natural gas combustion and VOC emissions from paraffin wax production. [2]

c

Evaluate whether the constant-temperature assumption for the PCM remains valid in a real thermal battery, considering heat-exchanger inefficiencies and impurities in the wax. [2]

Solutions

15QuestionEnergy transfer during state changes (heating/cooling curves)Assessment Practice

6 marks~9 minCriterion C

A heating curve shows the temperature of an unknown substance rising from

-50^\circ\text{C}

(solid) to

150^\circ\text{C}

(gas), with two plateaus: one at

0^\circ\text{C}

and one at

100^\circ\text{C}

.

Reference data:

Substance	Melting point ( $^\circ\text{C}$ )	Boiling point ( $^\circ\text{C}$ )
Water	0	100
Ethanol	−114	78
Mercury	−39	357
Methane	−182	−164

a

Deduce the identity of the unknown substance, using the plateau temperatures and the reference data to support your answer. [2]

b

Explain the changes in kinetic energy and potential energy of the particles during the segment of the heating curve between the two plateaus. [2]

c

A second heating curve shows plateaus at

-39^\circ\text{C}

and

357^\circ\text{C}

. Analyse whether this substance would exist as a solid, liquid, or gas at room temperature (

25^\circ\text{C}

), and evaluate what this implies about the strength of its intermolecular forces compared with water. [2]

Solutions

16QuestionFactors affecting diffusion rate (temperature, particle size)Assessment Practice

4 marks~6 minCriterion C

Two identical beakers of water are placed on a bench. Beaker A is at

20^\circ\text{C}

; Beaker B is at

60^\circ\text{C}

. One drop of blue dye is added to each beaker simultaneously.

a

State which beaker shows faster diffusion of the dye. [1]

b

Explain how temperature affects the kinetic energy of particles and, as a result, the rate of diffusion. [2]

c

A student claims that doubling the temperature (from

20^\circ\text{C}

to

40^\circ\text{C}

) will exactly double the diffusion rate. Evaluate this claim. [1]

Solutions

17QuestionFactors affecting diffusion rate (temperature, particle size)Assessment Practice

6 marks~9 minCriterion D

A chemical spill of volatile organic compounds (VOCs) occurs near a residential area. On a hot summer day (

35^\circ\text{C}

), VOCs diffuse rapidly into the air; on a cold winter day (

5^\circ\text{C}

), the same spill diffuses much more slowly.

a

Describe how the increase in temperature from

5^\circ\text{C}

to

35^\circ\text{C}

affects the kinetic energy of VOC molecules. [1]

b

Explain why the rate of diffusion of VOCs is greater at

35^\circ\text{C}

than at

5^\circ\text{C}

. [2]

c

Analyse the health implications for nearby residents on the hot day compared with the cold day, considering both the rate at which hazardous concentrations build up and the time available for protective action. [3]

Solutions

18QuestionReversible vs irreversible changesAssessment Practice

3 marks~5 minCriterion B

The table below shows the solubility of four salts in water at 20°C and 80°C.

Salt — Solubility at 20°C (g / 100 g water) — Solubility at 80°C (g / 100 g water)

$\text{NaCl}$	36	39
$\text{KNO}_3$	32	169
$\text{Ca(OH)}_2$	0.16	0.09
$\text{Na}_2\text{SO}_4$	19.5	43.7

a

State the general trend in solubility with increasing temperature for most solids in this data. [1]

b

Identify the salt that does not follow this trend and describe how its solubility changes between 20°C and 80°C. [1]

c

Explain whether dissolving

\text{Ca(OH)}_2

in water is a reversible or irreversible change, and justify your answer using evidence from the data. [1]

Solutions

19QuestionReversible vs irreversible changesAssessment Practice

8 marks~12 minCriterion D

A student heats 5.00 g of blue copper(II) sulfate pentahydrate (

CuSO_4 \cdot 5H_2O

) crystals in a crucible. The temperature rises steadily from 25 °C to 220 °C over 10 minutes, then holds at 220 °C for 5 minutes; the final mass is 3.20 g. The white solid is then left in a humid atmosphere for 24 hours, after which the mass is 4.50 g.

a

Write a balanced chemical equation, including state symbols, for the dehydration of

CuSO_4 \cdot 5H_2O

. [2]

b

Deduce the theoretical mass of water that should be lost during complete dehydration and compare it with the experimental mass loss. [2]

c

Analyse whether the overall change is chemically reversible. In your answer, refer to evidence for the formation of a new substance, the different conditions required for each reaction direction, and what the partial mass regain indicates about reversibility. [4]

Solutions

20QuestionReversible vs irreversible changesAssessment Practice

3 marks~5 minCriterion C

When sodium hydrogen carbonate is heated, it decomposes according to:

2NaHCO_3(s) \rightarrow Na_2CO_3(s) + H_2O(g) + CO_2(g)

The graph below shows how the mass of a solid mixture containing

NaHCO_3

changes as it is heated.

Graph: mass (g) on the y-axis; time (minutes) on the x-axis. Mass starts at 5.0 g, decreases sharply to approximately 3.2 g between 0 and 2 minutes, then remains constant at 3.2 g from 2 to 5 minutes.

a

Describe the trend shown in the graph. [1]

b

Identify whether this change is reversible or irreversible, and state one piece of evidence from the graph that supports your answer. [1]

c

Analyse why the mass loss alone is insufficient to conclude that a chemical change has occurred, and explain what additional evidence from the reaction equation confirms this conclusion. [1]

Solutions

Matter And the Particle Model — Free MYP4 Chemistry Practice Questions