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This question is about temperature changes - AQA - GCSE Chemistry - Question 1 - 2016 - Paper 2
Question 1
This question is about temperature changes. 1 (a) A student investigated the temperature change when 8 g of sodium nitrate dissolves in 50 cm³ of water. Figure 1 s... show full transcript
Worked Solution & Example Answer:This question is about temperature changes - AQA - GCSE Chemistry - Question 1 - 2016 - Paper 2
Step 1
Calculate the mean decrease in temperature.
Answer
To calculate the mean decrease in temperature, we will consider the results from the experiments, excluding the anomalous value. The results excluding the anomalous value (7.2 °C) are 5.9, 5.7, 5.6, and 5.8.
First, we sum these values:
Next, we divide by the number of experiments (4):
Thus, the mean decrease in temperature is 5.75 °C.
Step 2
Suggest one change in the apparatus in Figure 1 which would improve the accuracy of the results.
Answer
One change that could improve accuracy is to use a polystyrene cup or lid. This would help to insulate the beaker and prevent heat gain from the surroundings, leading to more precise temperature readings.
Step 3
Describe the relationship between the mass of sodium carbonate added and the final temperature of the solution.
Answer
As the mass of sodium carbonate increases from 2.0 g to 8.0 g, the final temperature of the solution also increases—from 21.5 °C to 26.0 °C. However, after reaching a mass of 8.0 g, the temperature stabilizes at 26.6 °C, showing that the temperature remains constant for additional mass increments of sodium carbonate beyond this point. This indicates that there is an initial positive correlation between mass added and temperature increase, which then levels off.