Matter And the Particle Model — Free IB MYP5 Chemistry Questions

1QuestionDensity differences between statesConcept Practice

2 marks~3 minCriterion A

The diagram below shows particle arrangements in three states of matter.

Box (a): particles arranged in a regular, tightly packed pattern.
Box (b): particles close together but arranged irregularly, able to slide past one another.
Box (c): particles far apart, moving freely and randomly.

a

Identify which box represents the state with the highest density. [1]

b

Explain why that state has the highest density, using particle spacing in your answer. [1]

Solutions

2QuestionDensity differences between statesConcept Practice

4 marks~6 minCriterion B

The diagrams below show equal numbers of particles arranged in three different states of matter within identical containers. The spacing between particles varies: in Diagram 1, particles are tightly packed; in Diagram 2, particles are loosely packed; in Diagram 3, particles are far apart.

Diagram 1: Solid (tightly packed particles)
Diagram 2: Liquid (loosely packed particles)
Diagram 3: Gas (far apart particles)

a

Investigate the pattern: For each diagram, calculate the density if each particle has a mass of 0.1 g and the container volume is 10 cm³. Use the formula density = mass/volume, where mass = number of particles × mass per particle.

b

Generalize a rule: Based on your calculations, describe the relationship between particle spacing and density.

c

Test your rule: A new diagram shows particles with moderate spacing. Predict whether this substance is most likely a solid, liquid, or gas, and justify your prediction using your rule.

Solutions

3QuestionParticle motion in solids, liquids, and gasesConcept Practice

2 marks~3 minCriterion A

The diagrams below show particle arrangements in three states of matter.

Diagram A: particles arranged in a regular, closely packed lattice.
Diagram B: particles close together but in no regular pattern.
Diagram C: particles far apart, moving randomly.

a

Identify the state of matter shown in Diagram A. [1]

b

Diagram C shows particles that are far apart and moving randomly. Deduce which property of a gas — compressibility or electrical conductivity — is directly explained by this particle arrangement, and justify your reasoning. [1]

Solutions

4QuestionConstant temperature during phase changesConcept Practice

2 marks~3 minCriterion A

The heating curve for water shows two flat regions — one at

0^\circ\text{C}

and one at

100^\circ\text{C}

.

a

State what the term "latent heat of fusion" refers to in the context of the flat region at

0^\circ\text{C}

. [1]

b

Explain why the kinetic energy of water molecules remains constant during the flat region at

0^\circ\text{C}

, even though energy is continuously being supplied. [1]

Solutions

5QuestionExamples 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

6QuestionDefinition of diffusion in gases and liquidsConcept Practice

2 marks~3 minCriterion A

A glass diffusion tube has cotton wool soaked in ammonia (

NH_3

) at one end and cotton wool soaked in hydrochloric acid (

HCl

) at the other. After several minutes, a white ring of ammonium chloride (

NH_4Cl

) forms inside the tube, closer to the

HCl

end.

a

Identify the apparatus used in this experiment. [1]

b

Explain what the position of the white ring demonstrates about the rates at which

NH_3

and

HCl

gases diffuse. [1]

Solutions

7QuestionDefinition of chemical change (new substances formed)Concept Practice

3 marks~5 minCriterion A

The diagram shows two processes at the particle level.

Process 1:

H_2O

molecules move farther apart while remaining intact.

Process 2:

CH_4

molecules and

O_2

molecules react to form

CO_2

molecules and

H_2O

molecules.

a

Identify which process represents a chemical change. [1]

b

Explain why Process 1 is classified as a physical change, referring to the definition of a chemical change in your answer. [2]

Solutions

8QuestionProperties of solids, liquids, and gases (shape, volume, compressibility)Assessment Practice

3 marks~5 minCriterion C

The graph below shows how the volume of a fixed mass of a substance changes as it is heated at constant pressure, passing through melting and then vaporisation.

a

State what happens to particle spacing as a substance changes from solid to liquid to gas. [1]

b

Explain why a gas is significantly more compressible than a liquid, using particle spacing. [1]

c

The graph shows a much larger volume increase during vaporisation than during melting. Analyse what this difference reveals about the relative compressibility of liquids and gases, and justify why solids are considered almost incompressible. [1]

Solutions

9QuestionProperties of solids, liquids, and gases (shape, volume, compressibility)Assessment Practice

6 marks~9 minCriterion D

Industrial refrigeration plants use either hydrofluorocarbons (HFCs) or ammonia (

\text{NH}_3

) as refrigerants. HFCs are non-toxic and highly compressible but carry a high global warming potential (GWP). Ammonia is a natural refrigerant with zero GWP and high efficiency but is toxic and requires strict handling protocols. Engineers must weigh immediate safety risks against long-term environmental harm when selecting a refrigerant.

a

Explain, using the particle model, why gases are compressible and how this property makes both HFCs and

\text{NH}_3

suitable as refrigerants. [2]

b

Compare the safety implications of using

\text{NH}_3

versus HFCs as refrigerants, linking your comparison to the physical properties of each gas. [2]

c

Evaluate the limitations of the particle model when assessing the real-world risks of refrigerant choice, including gas leaks and environmental impact. [2]

Solutions

10QuestionExplaining macroscopic properties using particle theoryAssessment Practice

7 marks~11 minCriterion B

The table below shows gas volumes for four reactions carried out at the same temperature and pressure.

Reaction 1:

2H_2 + O_2 \rightarrow 2H_2O

— volumes: 4 L, 2 L, 4 L

Reaction 2:

N_2 + 3H_2 \rightarrow 2NH_3

— volumes: 2 L, 6 L, 4 L

Reaction 3:

CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O

— volumes: 1 L, 2 L, 1 L, 2 L

Reaction 4:

2NO + O_2 \rightarrow 2NO_2

— volumes: 3 L, 1.5 L, 3 L

a

Analyse the data and state the pattern relating gas volumes to the coefficients in the balanced equations. Support your answer with one example from the data. [2]

b

Deduce the volume of

CO_2

produced when 6 L of

CO

reacts completely with excess

O_2

:

2CO + O_2 \rightarrow 2CO_2

Show your reasoning. [2]

c

Justify why, at constant temperature and pressure, volume ratios between reacting gases equal their mole ratios. Use the particle model in your answer, and evaluate whether this reasoning would still hold if pressure were doubled mid-reaction. [3]

Solutions

11QuestionExplaining macroscopic properties using particle theoryAssessment Practice

3 marks~5 minCriterion C

The diagram shows the particle arrangement of the same substance in its solid state (left) and liquid state (right).

a

Describe the spacing and movement of particles in the solid. [1]

b

Explain, using particle theory, why the solid maintains a fixed shape and volume while the liquid conforms to the shape of its container. [1]

c

A student claims: "If you heat the solid just enough to melt it, the particles must be moving faster, so the liquid should take up more volume than the solid." Evaluate this claim. [1]

Solutions

12QuestionExplaining macroscopic properties using particle theoryAssessment Practice

5 marks~8 minCriterion D

A student hypothesises that gas particles have negligible volume and exert no forces on each other. To test this, she measures the pressure of a fixed mass of gas at constant temperature across five volumes.

Volume ( $\text{cm}^3$ )	10	20	30	40	50
Pressure ( $\text{kPa}$ )	200	100	66.7	50	40

a

Calculate the product

P \times V

for each data point and deduce the mathematical relationship between pressure and volume. [1]

b

Explain how the particle model accounts for the observed relationship between pressure and volume at constant temperature. [2]

c

Evaluate the extent to which this experimental evidence supports the student's hypothesis, and discuss the limitations that prevent a universal conclusion. [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

14QuestionMelting, freezing, boiling, condensation, sublimationAssessment Practice

5 marks~8 minCriterion C

A student heats a pure solid substance from room temperature to above its boiling point, recording temperature every 30 seconds. The substance melts at

80^\circ\text{C}

and boils at

200^\circ\text{C}

.

Temperature data collected:
-

0

to

120

s: temperature rises from

20^\circ\text{C}

to

80^\circ\text{C}

(solid phase)
-

120

to

240

s: temperature remains at

80^\circ\text{C}

, except at

180

s where

82^\circ\text{C}

is recorded
-

240

to

360

s: temperature rises from

80^\circ\text{C}

to

200^\circ\text{C}

(liquid phase)
-

360

to

480

s: temperature remains at

200^\circ\text{C}

(boiling plateau)
- After

480

s: temperature rises (gas phase)

a

Identify the anomalous reading and state why it is inconsistent with the data collected during the melting plateau. [2]

b

Explain, in terms of particles and energy transfer, why temperature remains constant throughout the melting plateau. [2]

c

The boiling plateau also shows a constant temperature. Evaluate whether the energy transfer occurring at the boiling plateau is the same as, or different from, that occurring at the melting plateau, and justify your reasoning. [1]

Solutions

15QuestionConstant temperature during phase changesAssessment Practice

6 marks~9 minCriterion D

A factory uses acetone (boiling point 56 °C) to clean metal parts. During a summer heatwave, the storage shed reaches 55 °C. The acetone remains liquid despite being only 1 °C below its boiling point.

a

Explain why the acetone does not boil at 55 °C. In your answer, refer to vapour pressure and the energy required for the phase change. [2]

b

A temperature spike raises the shed to 70 °C, causing rapid vaporisation of the acetone. Discuss the health risks to workers and one environmental consequence of this event. [3]

c

Evaluate one assumption made in part (b) and assess how relaxing that assumption changes the severity of the risk. [1]

Solutions

16QuestionRelationship between kinetic energy and diffusion speedAssessment Practice

6 marks~9 minCriterion D

A factory leak releases tetrachloroethylene (C2Cl4, molar mass 166 g/mol) into an aquifer at 285 K. The solvent diffuses through the groundwater toward a municipal well 500 m away. The average kinetic energy of molecules is given by $E_k = \frac{3}{2}kT$ , where $k = 1.38 \times 10^{-23}$ J/K.

a

[2 marks] Calculate the root-mean-square speed of tetrachloroethylene molecules at 285 K. Use

v_{rms} = \sqrt{\frac{3kT}{m}}

, where

m

is the mass of one molecule in kg.

b

[1 mark] State one reason why the actual time for the solvent to reach the well is much longer than predicted by the root-mean-square speed alone.

c

[3 marks] Discuss the health implications of tetrachloroethylene reaching the municipal well. Your discussion should include:

Solutions

17QuestionBrownian motion and evidence for particle movementAssessment Practice

3 marks~5 minCriterion C

A graph shows the distance travelled by potassium permanganate (

\text{KMnO}_4

) crystals dissolving in water at 20 °C, 40 °C, and 60 °C over 10 minutes. The distance increases with temperature.

a

State what happens to the kinetic energy of water particles as temperature increases. [1]

b

Using the particle model, explain how this change in kinetic energy causes

\text{KMnO}_4

to spread further at higher temperatures. [1]

c

The graph shows that the distance travelled at 60 °C is approximately three times that at 20 °C, yet the temperature has not tripled. Explain why a relatively small increase in temperature produces a disproportionately large increase in diffusion distance. [1]

Solutions

18QuestionDefinition of chemical change (new substances formed)Assessment Practice

4 marks~6 minCriterion B

A student investigated whether new substances were formed in five experiments. The results are shown below.

Experiment 1: 10 g iron + 6 g sulfur → 16 g black solid. New substance formed: Yes. Reversible: No.
Experiment 2: 5 g salt + 50 g water → 55 g salt solution. New substance formed: No. Reversible: Yes.
Experiment 3: 10 g green powder → 6 g black powder + gas released. New substance formed: Yes. Reversible: No.
Experiment 4: 20 g solid wax → 20 g liquid wax. New substance formed: No. Reversible: Yes.
Experiment 5: 2 g magnesium → 3.3 g white ash. New substance formed: Yes. Reversible: No.

a

Deduce a general rule linking new substance formation, reversibility, and mass change, using evidence from at least two experiments. [2]

b

A sixth experiment heats a mixture of sand and sugar. The sugar chars to a black solid and a gas is released; the sand is unchanged. Justify whether a new substance is formed and whether the change is reversible, applying your rule from part (a). [2]

Solutions

19QuestionDefinition of chemical change (new substances formed)Assessment Practice

8 marks~12 minCriterion D

Polyethylene is a synthetic polymer produced by polymerising ethene gas under high pressure and temperature. This chemical change forms long-chain molecules with strong covalent C–C bonds throughout the backbone. Polyethylene is widely used in food packaging because of the properties that emerge from this new molecular structure. However, global plastic recycling rates remain below 10%, and polyethylene persists in the environment for hundreds of years.

a

Identify and explain two societal benefits of polyethylene packaging that arise directly from the properties of the polymer formed. [2]

b

Describe two environmental problems caused by polyethylene waste, linking each problem to the chemical nature of the polymer. [2]

c

Evaluate the sustainability of producing and using polyethylene packaging, considering the chemical stability of the polymer, current waste management limitations, and the balance between societal benefits and environmental costs. [4]

Solutions

20QuestionDefinition of physical change (no new substance formed)Assessment Practice

4 marks~6 minCriterion C

The diagram shows water molecules arranged in ice (fixed lattice, hydrogen bonds shown as dashed lines) and in steam (molecules far apart, moving freely).

a

State what is meant by a physical change. [1]

b

Explain, using the diagram, why melting ice is classified as a physical change rather than a chemical change. Refer to the bonds involved. [2]

c

A student claims that boiling water requires more energy than melting ice, so boiling must involve a chemical change. Evaluate this claim. [1]

Solutions

Matter And the Particle Model — Free MYP5 Chemistry Practice Questions