Explaining what's happening
3 marks · EasyThe reaction between powdered iron and dilute sulfuric acid produces hydrogen gas.
State what particles must do for a reaction to take place according to collision theory.
Name the term for the minimum amount of energy particles need to react when they collide.
Explain why the reaction slows down as the acid is gradually used up.
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(a) Collide with each other.
(b) Activation energy.
(c) There are fewer acid particles left, so fewer collisions occur per second.
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Marking points
B1 (a) · 1 mark · States that particles must collide (with each other) for reaction to occur.
B2 (b) · 1 mark · Correctly names activation energy.
B3 (c) · 1 mark · Explains that as acid is used up, fewer particles remain so collision frequency decreases and reaction slows.
Worked solution
a) According to collision theory, the reactant particles must collide with each other to react.
b) The minimum energy required is called the activation energy.
c) As the acid is used up, there are fewer acid particles to collide with the iron, so collisions per second (collision frequency) decrease, slowing the reaction.