S1.1 Introduction to the particulate nature of matter
Practice exam-style IB Chemistry questions for Introduction to the particulate nature of matter, aligned with the syllabus and grouped by topic.
Question 1
A sample contains only atoms with the symbol Fe. What type of matter is the sample?
A.
A homogeneous mixture
B.
An element
C.
A heterogeneous mixture
D.
A compound
Question 2
What state symbol represents a substance dissolved in water?
A.
(l)
B.
(g)
C.
(s)
D.
(aq)
Question 3
What distinguishes a compound from a mixture?
A.
A compound has components in a fixed ratio and chemically bonded.
B.
A compound can always be separated by filtration.
C.
A compound contains elements in any proportion.
D.
A compound must be heterogeneous.
Question 4
An insoluble solid is separated from an aqueous solution using filter paper. What are the names of the solid retained and the liquid collected?
A.
Distillate and residue
B.
Filtrate and residue
C.
Solute and solvent
D.
Residue and filtrate
Question 5
What change of state is represented by CO₂
A.
Condensation
B.
Deposition
C.
Sublimation
D.
Vaporization
Question 6
What is 35.0 °C expressed on the Kelvin scale?
A.
238.2 K
B.
350.0 K
C.
308.2 K
D.
273.2 K
Question 7
Define a pure substance.
[1]
Distinguish between a compound and a mixture in terms of bonding and composition.
[1]
Question 8
State the change of state for each process.
H₂O
[1]
→ H₂O
[1]
[1]
I₂
→ I₂
[1]
Question 9
Convert 18.0 °C to K.
[1]
Convert 250.0 K to °C.
[1]
Question 10
A mixture of ethanol and water is to be separated. Ethanol boils at a lower temperature than water. What physical property is used in distillation?
A.
Difference in colour
B.
Difference in particle size
C.
Difference in magnetism
D.
Difference in volatility
Question 11
During boiling of a pure liquid at constant pressure, what happens to the temperature and average kinetic energy?
A.
Both remain constant.
B.
Both increase continuously.
C.
Temperature increases and average kinetic energy is constant.
D.
Temperature is constant and average kinetic energy increases.
Question 12
A metal sample contains copper atoms and zinc atoms with metallic bonding and a composition that can vary between samples. How should the sample be classified?
A.
An alloy mixture
B.
A compound
C.
An element
D.
A pure molecular substance
Question 13
In paper chromatography, a spot travels furthest from the baseline. What does this indicate about the substance?
A.
It has the largest particle size.
B.
It has the greatest attraction to the stationary phase.
C.
It has the highest boiling point.
D.
It has the greatest attraction to the mobile phase.
Question 14
Which row gives the correct energy change for deposition and vaporization?
A.
Deposition endothermic; vaporization exothermic
B.
Both are exothermic
C.
Deposition exothermic; vaporization endothermic
D.
Both are endothermic
Question 15
Two samples of the same gas are at 300 K and 600 K. What is the relationship between their average kinetic energies?
A.
The 600 K sample has twice the average kinetic energy.
B.
The two samples have the same average kinetic energy.
C.
The relationship cannot be inferred from Kelvin temperature.
D.
The 600 K sample has half the average kinetic energy.
Question 16
A mixture contains sand and sodium chloride.
State a suitable solvent for sodium chloride.
[1]
Outline how the sand can be separated from the dissolved sodium chloride.
[1]
Question 17
Use the kinetic molecular theory to explain why a liquid has a fixed volume but no fixed shape. [3]
Question 18
A pure solid is heated at constant pressure and begins to melt.
State what happens to the temperature during melting.
[1]
Explain why energy is still required during melting.
[1]
Question 19
Classify each as an element, compound, homogeneous mixture or heterogeneous mixture.
Oxygen gas, O₂
[1]
Sodium chloride, NaCl
[1]
Oil and water after shaking and standing
[1]
Question 20
The graph shows a heating curve for a pure substance at constant pressure.
Identify the sections where a change of state occurs.
[1]
State what happens to the average kinetic energy during a sloping section.
[1]
Explain why the temperature is constant during a horizontal section.
[1]
Question 21
A paper chromatogram was obtained from a food dye mixture using water as the solvent.
Identify the mobile phase.
[1]
State the number of components shown in the mixture.
[1]
Suggest which component is most strongly attracted to the stationary phase and explain your choice.
[1]
Question 22
A flow chart shows the separation of a mixture of insoluble solid A and soluble solid B.
Identify the step where solvation occurs.
[1]
Name the solid collected on the filter paper.
[1]
Suggest a method to obtain dry solid B from the filtrate.
[1]
State the physical property used in filtration.
[1]
Question 23
A solid product dissolves well in hot ethanol but only slightly in cold ethanol. Most coloured impurities remain soluble when cold. What purification method is most suitable?
A.
Evaporation to dryness only
B.
Simple filtration of the dry mixture
C.
Paper chromatography of the bulk solid
D.
Recrystallization from ethanol
Question 24
A sealed syringe contains a gas. The plunger is pushed in at constant temperature. Which particle-level explanation best accounts for the observation?
A.
Gas particles are far apart, so the space between them decreases.
B.
Gas particles chemically bond to form a liquid.
C.
Gas particles become smaller under pressure.
D.
Gas particles stop moving randomly.
Question 25
A sample is cooled from 25 °C to −25 °C. What is the temperature change in kelvin?
A.
323 K
B.
223 K
C.
−50 K
D.
50 K
Question 26
A clear liquid evaporates completely at room temperature, leaving no residue. What conclusion is best supported?
A.
It contained no dissolved non-volatile solid detectable by this test.
B.
It was a heterogeneous mixture.
C.
It was definitely an element.
D.
It was definitely pure water.
Question 27
A student has an aqueous copper(II) sulfate solution and wants dry crystals.
State the separation technique used to remove some water before crystallization.
[1]
Outline how crystals are obtained after concentrating the solution.
[1]
State one reason not to heat strongly to complete dryness.
[1]
Question 28
An impure organic solid is purified by recrystallization.
Explain why a minimum volume of hot solvent is used.
[1]
State why the crystals are washed with a small volume of cold solvent.
[1]
Suggest why melting point determination can assess purity.
[1]
Question 29
In paper chromatography a component has a low Rf value.
State the stationary phase in paper chromatography.
[1]
Explain the low Rf value in terms of attractions.
[1]
Question 30
A colourless liquid has a boiling range of 78–82 °C and leaves a small white solid residue after evaporation.
State whether the evidence supports the liquid being pure.
[1]
Give two pieces of evidence for your answer.
[1]
State one limitation of using only these tests.
[1]
Question 31
A gas and a liquid are placed in identical sealed containers. The gas is much more compressible.
Describe the particle spacing in the gas compared with the liquid.
[1]
Explain why this produces greater compressibility.
[1]
Question 32
Frost can form on a very cold surface from water vapour in air.
Name the change of state.
[1]
State whether it is endothermic or exothermic and explain why.
[1]
Question 33
A table gives melting ranges for three samples of the same solid: crude product, recrystallized product and reference pure substance.
| Sample | Melting begins / °C | Melting ends / °C |
|---|---|---|
| Crude product | 121.4 | 126.8 |
| Recrystallized product | 128.0 | 129.1 |
| Reference sample | 128.4 | 129.0 |
Identify which sample is most pure.
[1]
State one feature of the data that indicates impurity.
[1]
Explain why melting point data can be used to assess purification.
[1]
Question 34
The diagram shows particle models for three samples X, Y and Z.
Identify the gas.
[1]
Identify the liquid.
[1]
Compare the arrangement and motion of particles in the solid and gas.
[1]
Question 35
The graph shows average kinetic energy for samples of the same gas at different temperatures.
Describe the relationship shown.
[1]
Explain why the graph passes through the origin when temperature is in K.
[1]
Predict the effect on average kinetic energy when the Kelvin temperature is tripled.
[1]
Question 36
Two samples of argon are at −50 °C and 50 °C.
Convert both temperatures to K.
[1]
Explain why 50 °C does not mean twice the average kinetic energy of −50 °C.
[1]
Question 37
A mixture contains iron filings, sand and sodium chloride.
State a physical property that could remove iron filings first.
[1]
Outline a sequence to obtain dry sodium chloride from the remaining mixture.
[1]
Question 38
A sample of brass contains copper and zinc. It conducts electricity and has metallic bonding between particles.
State why brass is not classified as a compound.
[1]
Explain why its properties can differ from pure copper.
[1]
Question 39
A table compares four possible solvents for recrystallizing a solid product.
| Solvent | Product solubility at 20 °C / g per 100 g | Product solubility near bp / g per 100 g | Impurity solubility at 20 °C / g per 100 g | bp / °C | Safety note |
|---|---|---|---|---|---|
| Water | 0.4 | 3.0 | 0.2 | 100 | Low hazard |
| Ethanol | 4.8 | 46 | 31 | 78 | Flammable |
| Propanone | 18 | 55 | 34 | 56 | Highly flammable |
| Hexane | 1.1 | 7.5 | 1.5 | 69 | Flammable; harmful |
Identify the most suitable solvent.
[1]
Give two reasons for your choice using the table.
[1]
Explain why the solvent should not react with the product.
[1]
State one safety or environmental factor that should also be considered.
[1]
Question 40
A distillation apparatus is shown for separating a volatile solvent from a solution.
Label the condenser.
[1]
State the role of the condenser.
[1]
Identify one error in the apparatus setup.
[1]
Explain how distillation separates the solvent from the dissolved solid.
[1]
Question 41
A cooling curve for a pure substance is shown.
Identify the section where condensation occurs.
[1]
State the sign of the energy change during condensation.
[1]
Explain the particle-level change during the plateau.
[1]
Question 42
Define an element and a compound.
[1]
Compare and contrast compounds and mixtures in terms of composition, bonding, properties and methods of separation.
[1]
Question 43
Describe the arrangement and motion of particles in a solid.
[1]
Explain, using the kinetic molecular theory, the differences in shape, volume and compressibility of solids, liquids and gases.
[1]
Question 44
A pure substance is heated from solid to gas at constant pressure.
State what is represented by sloping and horizontal regions on its heating curve.
[1]
Explain the changes in temperature, average kinetic energy and particle arrangement during heating, melting and boiling.
[1]
Question 45
A mixture contains a soluble salt, an insoluble impurity and water.
Identify two separation techniques that may be used to obtain a purified dry salt.
[1]
Discuss the sequence of operations and the physical property used in each step.
[1]
Question 46
A chromatogram compares an unknown ink U with three reference dyes A, B and C.
Identify which reference dye is present in U.
[1]
State whether U is pure or a mixture.
[1]
Explain your answer to (b).
[1]
Suggest why a component with the same height in two lanes may be the same substance.
[1]
State one reason chromatography alone may not prove identity conclusively.
[1]
Question 47
A reaction gives an impure solid product contaminated with insoluble particles and soluble coloured impurities.
Outline the main steps in recrystallization after the crude solid has been collected.
[1]
Evaluate how recrystallization and melting point determination can be used to improve and assess purity.
[1]
Question 48
A technician must separate a mixture containing two miscible liquids, a dissolved non-volatile solid and a coloured trace impurity.
State two physical properties that can be used in choosing separation methods.
[1]
Discuss suitable separation methods and practical limitations for this mixture.
[1]
Question 49
State the names and energy changes for vaporization and condensation.
[1]
Compare and contrast boiling, evaporation, condensation and deposition using particle motion, particle attractions and energy transfer.
[1]
Question 50
A student claims: “A sample at 40 °C has twice the average kinetic energy of a sample at 20 °C. During boiling, the average kinetic energy continues to increase because heat is being supplied.”
Convert 20 °C and 40 °C to kelvin.
[1]
Evaluate the student’s claim using the Kelvin scale and the kinetic molecular theory.
[1]
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