Syllabus Edition

First teaching 2014

Last exams 2024

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Intermolecular Forces & Metallic Bonding (DP IB Chemistry: SL)

Exam Questions

3 hours43 questions
1a2 marks

There are a number of different types of intermolecular force possible between molecules.

Which types of forces can be classified as 'van der Waals' forces?

1b2 marks

Methanol, CH3OH, is a small alcohol molecule that forms hydrogen bonds with water.

Sketch 2 different hydrogen bonding interactions between methanol and water.

1c4 marks

Methanol, CH3OH can be oxidised to methanal, CH2O and then to methanoic acid, HCOOH.

Identify the strongest type of intermolecular force between:

i)
Methanal molecules

ii)
Methanoic acid molecules

iii)
Water and methanal

iv)
Water and methanoic acid
[4]
1d3 marks

Methanoic acid reacts with sodium hydroxide to form sodium methanoate:

HCOOH + NaOH rightwards arrowHCOONa + H2O

Explain why sodium methanoate is a solid at room temperature and methanoic acid is a liquid.

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2a2 marks

Group 17 of the Periodic Table contain non-metals that are often referred to as the halogens.

Iodine, I2, is one of these halogens. At room temperature and pressure it exists as a grey-black solid.

Describe the bonding and forces present in I2 in the solid state.

2b2 marks

The state of the halogens changes down the group, with fluorine being a gas and astatine being a solid.

Explain why the melting point of the halogens increases down the group.

2c3 marks

The halogens are all diatomic covalent molecules.

Predict the most probable physical properties shown by all of the elements in Group 17.

2d3 marks

The halogens can also form interhalogen compounds, such as iodine monochloride, ICl.

Predict the state of iodine monochloride at room temperature and pressure, and explain your answer with reference to the intermolecular forces present.

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3a2 marks

Describe the bonding in solid sodium.

3b2 marks

Potassium has a lower melting point than sodium does.

Explain why.

3c2 marks

Magnesium is in the same period as sodium, but has a much higher melting point.

Explain why.

3d2 marks

Predict whether magnesium is harder or softer than sodium and explain why.

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4a2 marks

Copper is a common metal used in wiring.

Explain the electrical conductivity of copper.

4b2 marks
Explain why copper is also very malleable.
4c1 mark

Copper is used in alloys such as brass and bronze.

Outline why copper alloys are usually less malleable than pure copper.

4d2 marks

Copper is used for water pipes.

Suggest two properties of copper that make it suitable for this use, excluding malleability.

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1a3 marks

Magnesium is a lightweight metal used for the manufacturing of car seats. Describe the structure and bonding present in solid magnesium.

1b3 marks

Magnesium has a considerably higher boiling point than sodium. Explain this difference, despite the fact both elements are in period 3.

1c3 marks

Explain, with reference to bonding, the principal property of a metal that makes it suited to manufacturing shaped objects such as railings.

1d2 marks

Many alloys are harder than their constituent metal elements alone.

Outline the reason for this with reference to the structure of metal alloys.

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2a2 marks

Based on the type of intermolecular force present, explain why butan-1-ol has a higher boiling point than butanal.

2b2 marks

Ethane, C2H6, and disilane, Si2H6, are both hydrides of Group 4 elements with similar structures but different chemical properties.

Explain why disilane has a higher boiling point than ethane.

2c3 marks

Put the following molecules in order of increasing boiling point and explain your choice:

CH3CHO

CH3CH2OH

CH3CH2CH3

2d4 marks

Based on the type of intermolecular force present, explain the difference in solubility in water between ethane and ethanol.

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3a4 marks

The elements sodium, aluminium, silicon, phosphorus and sulfur are in period 3 of the periodic table.

Describe and explain the general trend in melting points of the metals in period 3.

3b3 marks

Identify, with reasoning, which of the period 3 metals has the highest melting point.

3c2 marks

Explain, by reference to the intermolecular forces, why sulfur has a higher melting point than phosphorus.

3d2 marks

Although the molar masses of ICl and Br2 are very similar, the boiling point of ICl is 97.4 °C and that of Br2 is 58.8 °C.

Explain the difference in these boiling points in terms of the intermolecular forces present in each liquid.

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4a3 marks

The melting points of some Group 1 elements are listed in Table 1.

Table 1

 

Na

K

Rb

Melting point / °C

98

63

 

Predict, with a reason, the melting point of Rb.

4b2 marks

Explain why ammonia, NH3, is a gas at room temperature. 

4c3 marks

Phosphine (IUPAC name phosphane) is a hydride of phosphorus, with the formula PH3. Phosphine has a much greater molar mass than ammonia.

Explain why phosphine has a significantly lower boiling point than ammonia.

4d2 marks

Identify the type of interaction that must be overcome when liquid hydrazine, N2H4, vaporizes. Suggest, with a reason, whether hydrazine has a lower or higher boiling point than diimide, N2H2.

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5a2 marks

Copper is a transition metal. Describe the bonding in metals.

5b2 marks

Aluminium and copper can be used to make the alloy duralumin.

Explain why an aluminium-copper alloy is harder than pure aluminium.

5c2 marks

This question is about the chlorides of copper and aluminium.

 

(i)
State the type of bonding present in copper(II) chloride which melts at 771 K.

 

(ii)
The chloride of aluminium, AlCl3, melts 465 K. Suggest why the melting point is so much lower than that of CuCl2.
5d2 marks

Both copper and benzene have delocalised electrons. Explain why both structures have delocalised electrons, copper conducts electricity, but benzene does not.

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1a3 marks

Explain why methanol is soluble in water.

1b4 marks

Methanol, ethanol and propan-1-ol are all primary alcohols. Describe and explain the trend in their melting points shown below.

 
Alcohol

Methanol

CH3OH

Ethanol

C2H5OH

Propan-1-ol

C3H7OH

Melting point / oC -97 -114 -126

1c4 marks

These longer primary alcohols have the following melting points:

 

Alcohol C4H9OH C5H11OH C6H13OH C7H15OH C8H17OH C9H19OH C10H21OH
Melting point / oC -90 -79 -52 -34 -16 -6 6

Describe and explain this trend.

1d2 marks

Predict, with a reason, whether ethanol or ethane-1,2-diol will have the higher melting point?

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2a6 marks

C2H6, C4H10 and C3H8 are alkanes.

i)
Put them in order of increasing boiling point and explain your answer.
[3]
ii)
Put them in order of increasing volatility and explain your answer.

[3]

2b5 marks
Predict, with a reason, whether the alkanes are soluble in water and propanone.

2c5 marks

Pentane can exist as isomers, including pentane, CH3CH2CH2CH2CH3 and 2,2-dimethylpropane, CH3C(CH3)2CH3.

i)
Draw skeletal formula for each isomer shown above.
[2]
ii)
Predict and explain which isomer of pentane would have the greater volatility.

[3]

2d5 marks

There are two isomers possible with the molecular formula C2H6O.

i)
Draw the skeletal formulae of both isomers

[2]

ii)
Identify the strongest type of intermolecular force present in each isomer

[2]

iii)
Predict which isomer would have the higher melting point

[1]

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3a2 marks

Explain why transition metals, such as iron, alloy best with other transition metals, such as nickel.

3b2 marks

State the name of the most common type of iron alloy and the element it is alloyed with.

3c3 marks

Describe and explain the trend in the melting points of all the Group 1 metals as you descend the group.

Use page 7 of the Data book.

3d3 marks

Describe and explain the trend in melting points across the Period 3 metals of sodium, magnesium and aluminium.

Use page 7 of the Data book.

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4a2 marks
Explain why pure gold is not often used to make jewellery.

4b4 marks
b)
Gold is often alloyed with other metals.

i)
Suggest why alloying gold is useful.

[2]

ii)
Give some examples of metals that are commonly alloyed with gold.

[2]

4c3 marks
c)
Silver is the best metal electrical conductor.

i)
Explain how silver conducts electricity so well.

[2]

ii)
Explain why copper is often used instead of silver in wiring.

[1]

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