Some reactions are exothermic and some reactions are endothermic - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2022 - Paper 1
Question 2
Some reactions are exothermic and some reactions are endothermic.
(a) What does an exothermic reaction always give out?
A heat energy
B light
C a gas
D sound
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Worked Solution & Example Answer:Some reactions are exothermic and some reactions are endothermic - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2022 - Paper 1
Step 1
What does an exothermic reaction always give out?
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Answer
An exothermic reaction always gives out heat energy, making option A the correct choice.
Step 2
Give the letter of the piece of apparatus that is used to measure the temperature.
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Answer
The piece of apparatus used to measure the temperature is labelled A in Figure 3.
Step 3
Give the name of the piece of apparatus B shown in Figure 3.
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Answer
The piece of apparatus B is known as a thermometer.
Step 4
State why polystyrene is a better material than glass for this piece of apparatus.
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Answer
Polystyrene is a better material than glass for this piece of apparatus because it is an insulating material, minimizing heat loss to the surroundings and ensuring more accurate temperature measurement.
Step 5
Calculate the change in temperature. Give a sign and a unit in your answer.
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Answer
To calculate the change in temperature:
delta T = T_{final} - T_{initial} = 16.1 °C - 18.6 °C = -2.5 °C
Therefore, the change in temperature is -2.5 °C.
Step 6
Give the formula and the name of the solid.
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Answer
The formula of the solid is NH₄NO₃ and its name is ammonium nitrate.
