EduNinja

Edexcel IAL Chemistry AS Topic 7 Intermolecular forces

Edexcel IAL Chemistry AS Topic 7 Intermolecular forces
Pearson Edexcel IAL Chemistry syllabusChemistry YCH11First assessment 2019

Identify every force present, compare electron number, shape and hydrogen-bond donors or acceptors and connect total attraction to boiling, solubility or layer position.

Exam points

  • Classify London forces, permanent dipoles and hydrogen bonding from structures.
  • Explain boiling trends through electron number, molecular shape and hydrogen bonding.
  • Interpret solvent, hydration and layer evidence for molecular and ionic substances.

Question 3

[Maximum number: 1]

Which of these compounds would be expected to have the highest boiling temperature?

A

(CH3)3COH\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}

B

CH3CH2CH2CH2OH\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}

C

CH3CH2CH(CH3)2\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}\left(\mathrm{CH}_{3}\right)_{2}

D

CH3CH2CH2CH2CH3\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}

Question 6

[Maximum number: 1]

Which is not correct about ice?

A

ice has a lower density than water

B

H2O\mathrm{H}_{2} \mathrm{O} molecules are further apart in ice than in water

C

the H-O-H bond angle is the same in ice and in water

D

H2O\mathrm{H}_{2} \mathrm{O} molecules in ice are held together by hydrogen bonds

Question 8

[Maximum number: 2]

This question is about alkanes.

Question 8(a)

(a)

Which of these alkanes has the highest boiling temperature?

A

butane

B

hexane

C

pentane

D

propane

[ 1 ]

Question 8(b)

(b)

Which of these alkanes has the lowest boiling temperature?
□ A

Question image

□ B

Question image

□ C

Question image

□ D

Question image
[ 1 ]

Question 16

Which row shows the hydrogen halides in order of increasing boiling temperature?
□ A
□ B
□ C
□ D

Table

Question 13

[Maximum number: 5]

Enthalpy changes of formation are often difficult to determine directly.
Some enthalpy data are shown.

Table

Standard enthalpy change of combustion of propane (ΔcH⊖(C3H8))=−2219 kJ mol−1\left(\Delta_{\mathrm{c}} H^{\ominus}\left(\mathrm{C}_{3} \mathrm{H}_{8}\right)\right)=-2219 \mathrm{~kJ} \mathrm{~mol}^{-1}.

Question 13(b)

(a)

The values for the boiling temperatures and the standard enthalpies of combustion of a series of straight-chain alkanes are shown in the table.

Table
[ 5 ]

Question 13(b)(ii)

(i)

The increase in the value of ΔcH⊖\Delta_{\mathrm{c}} H^{\ominus} from butane to pentane is smaller than any other increase.

Suggest an explanation for this.

[ 2 ]

Question 13(b)(iii)

(ii)

Explain, with reference to their intermolecular forces, why the boiling temperatures of alkanes increase as the number of carbon atoms increases. A detailed description of the intermolecular forces is not required.
(3)

[ 3 ]

Question 16(d)

[Maximum number: 4]

This question is about the halogens and some of their compounds.

The graph shows the boiling temperatures of the hydrogen halides.

Question image

Explain the trend in the boiling temperatures of the hydrogen halides.

Question 24(a)

[Maximum number: 3]

Some diesel cars contain an extra catalytic converter for the reduction of nitrogen oxides (NOx)\left(\mathrm{NO}_{\mathrm{x}}\right) in exhaust gases.
A solution of urea is used for this process.

Question image

urea

Urea has a melting temperature of 133∘C133^{\circ} \mathrm{C}.

Explain why this value is higher than expected for a relatively small molecule.
(3)