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An experiment is carried out to measure the temperature change when solid ammonium chloride is dissolved in water - Edexcel - GCSE Chemistry - Question 5 - 2012 - Paper 1
Question 5
An experiment is carried out to measure the temperature change when solid ammonium chloride is dissolved in water. initial temperature of water = 19 °C final temper... show full transcript
Worked Solution & Example Answer:An experiment is carried out to measure the temperature change when solid ammonium chloride is dissolved in water - Edexcel - GCSE Chemistry - Question 5 - 2012 - Paper 1
Step 1
Explain what the temperature readings show about the type of heat change occurring when ammonium chloride dissolves in water.
Answer
The temperature readings indicate that the process is endothermic. This can be inferred from the decrease in temperature from 19 °C to 15 °C, which suggests that heat energy has been absorbed from the water as the ammonium chloride dissolves. Therefore, the dissolution of ammonium chloride requires energy input from the surroundings, leading to a drop in the water's temperature.
Step 2
Use this information to complete the diagram.
Answer
In the diagram, the reactants are represented at a higher energy level, while the products are shown at a lower energy level. The line connecting the reactants to the products must be horizontal until reaching the reactants' energy level, followed by a downward slope to reflect the release of heat energy, indicating that the reaction is exothermic.