Photo AI
This question is about an experiment to estimate absolute zero - AQA - A-Level Physics - Question 3 - 2018 - Paper 3
Question 3
This question is about an experiment to estimate absolute zero. Figures 9a to 9d show the stages in the procedure carried out by a student. An empty flask fitted w... show full transcript
Worked Solution & Example Answer:This question is about an experiment to estimate absolute zero - AQA - A-Level Physics - Question 3 - 2018 - Paper 3
Step 1
Explain why the volume of the air in the flask in Figure 9c is less than the volume of the air in the flask in Figure 9d.
Answer
The volume of the air in the flask in Figure 9c is less than in Figure 9d because, in 9c, when the valve is opened, water enters the flask. As water occupies space within the flask, the volume available for the air is reduced. In contrast, in Figure 9d, the valve is closed, and the air is trapped at a larger volume.
Step 2
Explain why Charles’s Law can be applied to compare the air in the flask in Figure 9c with the air in the flask in Figure 9d.
Answer
Charles’s Law states that the volume of a gas is directly proportional to its temperature when the pressure is constant. Since the air in both Figures 9c and 9d is at the same pressure, and we are comparing the volumes at different temperatures, Charles’s Law is applicable.
Step 3
Explain how V1 and V2 can be determined.
Answer
To determine V1 and V2, a suitable measuring instrument such as a measuring cylinder or volumetric flask can be used to accurately measure the volume of water. A systematic error can be minimized by ensuring that the measurement is taken at eye level and ensuring that the meniscus is read accurately at the bottom for clear visibility.
Step 4
Plot on Figure 11 points to show the volume V' and the temperature t of the air in the flask when the flask is as shown in Figure 9a and the flask is as shown in Figure 9d.
Answer
Using the provided values, plot the points corresponding to V' against t on the graph. For the hot water bath at 86 °C, use V' = 48 cm³, and for the room temperature of 19 °C, use V' = V1 = 255 cm³. Connect these points to show the relationship as per Charles's Law.
Step 5
Add a best fit line to your graph in Figure 11 to show how V' should vary with t according to Charles’s Law.
Answer
To add a best fit line, draw a line that best represents the trend of the plotted points, ensuring it is as close to the majority of the points as possible while extending to indicate the expected linear relationship between volume and temperature.
Step 6
Determine the value of absolute zero in °C using your graph in Figure 11.
Answer
Absolute zero can be determined by extending the best fit line on the graph until it intersects the temperature axis (t = 0 °C). The temperature corresponding to the volume of zero air will give the value of absolute zero.