Uses of aluminium
2 marks · EasyA piece of pure aluminium can support a maximum load of 90 N before it bends permanently. An alloy of aluminium of the same size supports a load of 190 N before permanent bending. Calculate the difference in maximum loads supported, and state the reason for this difference.
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100 N; alloy is stronger due to atoms disrupting regular layers. N (±1)
Also accept: The alloy supports 100 N more than pure aluminium; Difference is 100 N
Common mistakes: Subtracting in wrong order; Not stating a reason
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Marking points
M1 · 1 mark · Calculates difference: 190 N - 90 N = 100 N
B1 · 1 mark · States that the alloy is stronger because different sized atoms (from other elements) disrupt the layers.
Worked solution
The alloy is stronger because adding other elements disrupts the regular arrangement of atoms, making it more difficult for layers to slide.