Photo AI
1 (a) A student investigated the temperature change when 8 g of sodium nitrate dissolves in 50 cm³ of water - AQA - GCSE Chemistry - Question 1 - 2016 - Paper 2
Question 1
1 (a) A student investigated the temperature change when 8 g of sodium nitrate dissolves in 50 cm³ of water. Figure 1 shows the apparatus the student used. The stu... show full transcript
Worked Solution & Example Answer:1 (a) A student investigated the temperature change when 8 g of sodium nitrate dissolves in 50 cm³ of water - 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 first exclude the anomalous result (which is 7.2 °C). The remaining results are 5.9 °C, 5.7 °C, 5.6 °C, and 5.8 °C. We add these values together:
Next, we divide this sum by the number of experiments, which is 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. Give a reason for your answer.
Answer
One change that could improve accuracy is to use a polystyrene cup or lid to insulate the beaker. This would help to prevent heat gain from the surroundings, ensuring more accurate 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, the final temperature of the solution also increases, reaching a peak at 10 g, where the temperature is 26.6 °C. Beyond this amount, adding more sodium carbonate (12 g and 14 g) does not further increase the temperature, indicating that the solution has stabilized at this temperature. Thus, the temperature increases with mass up to a point and then remains constant.