1. A student investigated the rate of reaction between calcium carbonate (marble chips) and hydrochloric acid - AQA - GCSE Chemistry - Question 1 - 2015 - Paper 2
Question 1
1. A student investigated the rate of reaction between calcium carbonate (marble chips) and hydrochloric acid. The student used the apparatus shown in Figure 1.
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Worked Solution & Example Answer:1. A student investigated the rate of reaction between calcium carbonate (marble chips) and hydrochloric acid - AQA - GCSE Chemistry - Question 1 - 2015 - Paper 2
Step 1
State one conclusion the student could make about the effect of temperature on the rate of the reaction.
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Answer
The student could conclude that higher temperatures increase the rate of the reaction.
Step 2
Give one reason why the student could make this conclusion.
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Answer
This conclusion can be made because the graph shows that at 40 °C, the reaction completes faster compared to 20 °C.
Step 3
Calculate the average rate of reaction from 0 to 15 seconds.
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Answer
The average rate of reaction can be calculated using the formula:
extRate=TimeVolume of gas
Here, the volume is 30 cm³, and the time interval is 15 seconds, so:
Rate=15 s30 cm3=2 cm3/exts
Step 4
Which two variables should the student keep constant? Tick (✓) two boxes.
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Answer
Concentration of acid
Mass of marble chips
Step 5
Explain, in terms of particles and collisions, the effect that increasing the surface area of the marble chips has on the rate of reaction.
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Answer
Increasing the surface area of marble chips allows more particles to be exposed and available for collisions with acid particles. This results in a higher frequency of collisions, leading to an increase in the rate of the reaction.
Step 6
Give one reason why using a catalyst reduces costs.
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Answer
Using a catalyst increases the rate of reaction, allowing for lower energy costs and reducing the time needed for production.
