Changing the surface area of the reactants
3 marks · EasyIron filings (very small pieces) and an iron nail (large piece) are both placed separately into dilute sulfuric acid. The mass of each iron sample is the same.
State which form of iron will react more quickly.
Describe two reasons why the form you selected in (a) reacts faster.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Iron filings
(b) 1. Iron filings have a larger surface area in contact with the acid. 2. More particles are exposed, increasing the chance of collisions so the reaction is faster.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly states iron filings.
M1 (b) · 1 mark · Mentions greater/larger/more surface area exposed for filings.
M2 (b) · 1 mark · Mentions more particles involved/available; or more frequent collisions.
Worked solution
a) Iron filings
b) Iron filings have a larger surface area, so more particles are exposed to react. This means more collisions happen per second, so the reaction goes faster.