S2.4 From models to materials questions for IB Chemistry
89 questions on From models to materials, written by Augment in the style of IB exam papers. Six of them are below in full, to answer on paper.
- IB Chemistry
- Part of S2 Models of bonding and structure
- SL and HL
Questions by paper and level
SL and HL questions are for students at either level. HL only questions cover what only HL students study.
| Paper | SL and HL | HL only | All |
|---|---|---|---|
| Paper 1A | 30 | 7 | 37 |
| Paper 1B | 14 | 3 | 17 |
| Paper 2 | 25 | 10 | 35 |
| Every paper | 69 | 20 | 89 |
Counted on
Questions to try
Written by Augment in the style of IB exams, not past papers. Answer them on paper, then check each one against its markscheme with a free account.
Which compound has the greatest ionic character? Use section 9 of the data booklet.
A student investigated how the percentage of zinc in brass (an alloy of copper and zinc) affects its hardness. A steel ball was dropped from a fixed height onto flat samples of each alloy and the diameter of the dent was measured with vernier calipers. A smaller dent means a harder metal.
Zinc / % by mass | Trial 1 diameter / mm ± 0.02 mm | Trial 2 diameter / mm ± 0.02 mm | Trial 3 diameter / mm ± 0.02 mm |
|---|---|---|---|
0 | 3.42 | 3.38 | 3.46 |
10 | 3.10 | 3.14 | 3.06 |
20 | 2.88 | 2.84 | 2.92 |
30 | 2.70 | 2.63 | 2.95 |
40 | 2.55 | 2.51 | 2.53 |
- (a)
Identify the independent variable, the dependent variable and one controlled variable.
2 marks
- (b)
Identify the anomalous result and calculate the mean diameter for 30 % zinc without it.
2 marks
- (c)
Describe the relationship between the percentage of zinc and the hardness of the alloy.
1 mark
- (d)
Explain, in terms of bonding and structure, why brass is harder than pure copper.
2 marks
- (e)
Pure copper is easily bent. State why the metallic bond is not broken when copper is bent.
1 mark
- (f)
Suggest one improvement to the method that would make the dent diameters more reliable.
1 mark
Overhead power cables can be made from aluminium or copper. Both metals conduct electricity, but their properties differ.
Property | Aluminium | Copper |
|---|---|---|
Density / g cm−3 | 2.70 | 8.96 |
Resistivity / × 10−8 Ω m | 2.65 | 1.68 |
Melting point / °C | 660.3 | 1085 |
A wire with a higher resistivity must have a larger cross-sectional area to have the same resistance. For equal resistance, the cross-sectional area of a cable is directly proportional to the resistivity of its metal.
- (a)
An aluminium cable is 1.00 km long and has a cross-sectional area of 3.00 cm2. Calculate the mass, in kg, of the cable.
2 marks
- (b)
Determine the mass, in kg, of a copper cable of the same length that has the same resistance.
2 marks
- (c)
Using your answers to (a) and (b), suggest why aluminium is preferred for overhead cables.
1 mark
- (d)
Pure aluminium is soft, so the cables are made of an aluminium alloy wound around a steel core. Explain why an alloy is stronger than the pure metal.
2 marks
Which pair of elements is most likely to form a substance with metallic bonding?
A student measured the electrical resistance of wires made of three transition metals and an alloy, constantan (55 % copper, 45 % nickel), to find their resistivity, ρ.
where R is the resistance, A the cross-sectional area, L the length and d the diameter of the wire.
Each wire was 2.000 m ± 0.001 m long. The diameter of each wire, measured with a micrometer, was 0.40 mm ± 0.01 mm. The resistance was measured with a digital ohmmeter.
Wire | Resistance / Ω ± 0.01 Ω | Literature resistivity / × 10−8 Ω m |
|---|---|---|
copper | 0.27 | 1.68 |
nickel | 1.12 | 6.99 |
iron | 1.55 | 9.71 |
constantan | 7.79 | 49.0 |
- (a)
Show that the cross-sectional area of each wire is 1.26 × 10−7 m2.
1 mark
- (b)
Calculate the resistivity of copper, in Ω m.
1 mark
- (c)
Determine the percentage uncertainty in the resistivity of copper. Use section 23 of the data booklet.
3 marks
- (d)
Comment on whether the student's value for copper agrees with the literature value.
1 mark
- (e)
Suggest one modification that would reduce the percentage uncertainty in the resistivity of copper.
1 mark
- (f)
Explain why transition metals such as nickel and iron conduct electricity.
2 marks
- (g)
Constantan has a much higher resistivity than either copper or nickel. Suggest why.
1 mark
Gold has been used for jewellery for thousands of years. It can be hammered into gold leaf less than 0.0001 mm thick.
- (a)
Explain why gold can be hammered into very thin sheets.
2 marks
- (b)
Outline why gold jewellery stays shiny for many years.
1 mark
- (c)
Pure gold is too soft for many rings, so jewellers use 18-carat gold, an alloy of gold with copper and silver. Explain why the alloy is harder than pure gold.
2 marks
- (d)
18-carat gold is 75.0 % gold by mass. Calculate the number of gold atoms in a 5.20 g ring made of 18-carat gold.
2 marks
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More questions in Models of bonding and structure
- S2.1The ionic model
- S2.2The covalent model
- S2.3The metallic model
- S2.4From models to materialsThis page
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