IB Chemistry SL Structure 1: Models of the particulate nature of matter questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

Type

Multiple choice Written

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Question 1

Paper 2Hard8 marks

A sample of ice is heated at constant pressure. Figure 1 shows the structural formula of the substance. The temperature is recorded at intervals.

Time / min	Temperature / °C
0.0	−8.2
2.0	−2.1
4.0	0.0
6.0	0.0
8.0	8.1
10.0	32.2

(a)

State the formula of each particle in the sample, using Figure 1.

[1]

(b)

Convert the temperatures recorded at 8.0 min and 10.0 min to kelvin, to the nearest kelvin.

[2]

(c)

Identify the time interval during which the sample is changing state.

[1]

(d)

A student concludes: “At 10.0 min, the average kinetic energy of the particles is about four times its value at 8.0 min, because 32.2 is about four times 8.1. The average kinetic energy also continues to increase from 4.0 to 6.0 min because the sample is still being heated.”

Evaluate both statements, using the data and your answer to (b).

[4]

Question 2

Paper 2Hard10 marks

A laboratory checks a powdered reference blend containing only paracetamol and caffeine. The structures of the two compounds are shown in Figure 1.

A sample of the blend has a mass of 1.6754 g and contains a total amount of 0.01000 mol of molecules. A quality-control note states that the two compounds are present in equal masses.

(a)

Use Figure 1 and the Ar values in the data booklet to determine the molecular formula and Mr of each compound.

[4]

(b)

Determine the amount, in mol, of each compound in the sample. Show your reasoning.

[4]

(c)

Calculate the mass of each compound in the sample and state whether the quality-control note is supported.

[2]

Question 3

Paper 2Hard12 marks

A laboratory is checking whether the ideal-gas model gives reliable volume estimates for gases in a transfer line. Samples of carbon dioxide and methane are measured at $280\ \mathrm{K}$ The table gives their measured molar volumes and the ideal-gas molar volume at each pressure.

Pressure / bar	Ideal-gas molar volume / dm³ mol⁻¹	Measured CO₂ molar volume / dm³ mol⁻¹	Measured CH₄ molar volume / dm³ mol⁻¹
1.00	23.3	23.1	23.2
5.00	4.66	4.54	4.63
10.0	2.33	2.14	2.29
20.0	1.16	0.94	1.11

(a)

Use Figure 1 to determine the molecular formula of each gas.

[2]

(b)

For an ideal-gas sample of $1.00\ \mathrm{mol}$ at $280\ \mathrm{K}$ and $20.0\ \mathrm{bar}$ calculate the molar volume. Give your answer in $\mathrm{dm^3\,mol^{-1}}$ to three significant figures. Use the ideal gas equation in the data booklet.

[2]

(c)

At $1.00\ \mathrm{bar}$ compare the measured molar volume of each gas with the ideal-gas value.

[2]

(d)

Explain why real gases are more likely to deviate from the ideal-gas model at low temperature and high pressure.

[2]

(e)

A technician argues that the ideal-gas model is equally reliable for carbon dioxide and methane at $280\ \mathrm{K}$ and $20.0\ \mathrm{bar}$ because the ideal molar volume is the same for both gases. Evaluate this argument using the table and Figure 1.

[4]

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