AQA · Chemistry · 8462
GCSE Chemistry (AQA): Factors Affecting Rates of Reaction & Collision Theory
Topic 6 — The Rate & Extent of Chemical Change. Generated from the caption track of Cognito's lesson video "GCSE Chemistry - Factors Affecting Rate of Reaction & Collision Theory (2027/28 exams)"; each card deep-links to the moment in the video it came from. Lesson 6.02 of Cognito's AQA GCSE Combined Science (Trilogy) and Chemistry course (Higher tier), filed under AQA Chemistry 8462. Teaching by Cognito — https://cognitoedu.org/coursesubtopic/c2-gcse-aqa-h-c_6.02.
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Define a catalyst.
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A substance that speeds up a reaction without being used up in it.
How does a catalyst speed up a reaction?
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It provides an alternative reaction pathway with a lower activation energy, so a higher proportion of collisions are successful.
Which two things determine the rate of a reaction in collision theory terms?
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The energy of the particles and the frequency of collisions.
On a reaction profile, the activation energy is the difference between the reactants' energy level and the ?.
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top of the curve
Why does increasing concentration increase the rate of reaction?
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There are more particles per unit volume, so collisions are more frequent.
What are enzymes, in terms of catalysis?
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Catalysts made by living organisms.
Define activation energy.
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The minimum energy particles must have when they collide for a reaction to occur.
What happens when particles collide with less than the activation energy?
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No reaction occurs — they simply bounce apart.
Which group of metals is a common source of catalysts?
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The transition metals, e.g. cobalt and nickel.
Why does increasing temperature increase the rate of reaction?
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Particles move faster, so they collide more frequently and with more energy, giving more successful collisions.
Why are concentration and pressure treated as the same rate factor?
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Both describe how many particles there are per unit volume — concentration for solutions, pressure for gases.
Why are catalysts not included in a reaction equation?
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They are neither reactants nor products — they are not used up.
Which form of 3 g of magnesium reacts fastest with acid: a block, chunks, or powder?
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Powder — it has the highest surface area to volume ratio, so collisions with the acid are more frequent.
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