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Aluminium alloys are used instead of pure aluminium in aircraft manufacture - Edexcel - GCSE Chemistry - Question 10 - 2021 - Paper 1
Question 10
Aluminium alloys are used instead of pure aluminium in aircraft manufacture. (a) Explain, in terms of the arrangement of metal particles, why aluminium alloys are s... show full transcript
Worked Solution & Example Answer:Aluminium alloys are used instead of pure aluminium in aircraft manufacture - Edexcel - GCSE Chemistry - Question 10 - 2021 - Paper 1
Step 1
Explain, in terms of the arrangement of metal particles, why aluminium alloys are stronger than pure aluminium.
Answer
Aluminium alloys are stronger than pure aluminium due to the arrangement of metal particles within the alloy. In an alloy, different metal particles disrupt the regular arrangement of atoms found in pure aluminium, creating a more complex structure. This disruption hinders the movement of dislocations, which are defects in the crystal lattice that allow deformation. As a result, the alloy exhibits greater strength and hardness compared to pure aluminium.
Step 2
Calculate the mass of aluminium in this sample.
Answer
To find the mass of aluminium in the sample, we first calculate the mass of magnesium:
- Mass of magnesium = 2.00% of 695.0g
- Mass of magnesium = (2.00/100) * 695.0g = 13.90g
Next, we subtract the mass of magnesium from the total mass of the alloy to find the mass of aluminium:
- Mass of aluminium = Total mass - Mass of magnesium
- Mass of aluminium = 695.0g - 13.90g = 681.10g
Step 3
Describe what Figure 12 shows about the relative strength of these alloys when the percentage by mass of magnesium changes.
Answer
Figure 12 demonstrates a direct relationship between the percentage by mass of magnesium in the alloy and its relative strength. As the percentage of magnesium increases, the relative strength of the alloy also increases, indicating that the addition of magnesium enhances the overall strength of the aluminium-magnesium alloy.
Step 4
Determine, using Figure 12, the percentage by mass of aluminium in an aluminium-magnesium alloy with a relative strength of 103.
Answer
Referring to Figure 12, a relative strength of 103 corresponds to a percentage by mass of magnesium of approximately 2.5%. To find the percentage by mass of aluminium, we can assume that the alloy is comprised of aluminium and magnesium:
- Percentage by mass of aluminium = 100% - Percentage by mass of magnesium
- Percentage by mass of aluminium = 100% - 2.5% = 97.5%
Step 5
Give two reasons why metal objects are electroplated with gold.
Answer
- Gold provides a corrosion-resistant surface, which protects the underlying metal from tarnishing or rusting.
- Gold has a pleasing aesthetic quality, giving the metal object an attractive finish that enhances its visual appeal.