Thermal Properties of Matter
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Question : 5
Total: 22
Two ideal gas thermometers A and B use oxygen and hydrogen respectively. The following observations are made :
(a) What is the absolute temperature of normal melting point of sulphur as read by thermometers A and B?
(b) What do you think is the reason behind the slightly difference in answers of thermometers A and B? (The thermometers are not faulty). What further procedure is needed in the experiment to reduce the discrepancy between the two readings?
| Temperature | Pressure | |
|---|---|---|
| thermometer A | thermometer B | |
| Triple-point of water | | |
| Normal melting point of sulphur | | |
(b) What do you think is the reason behind the slightly difference in answers of thermometers A and B? (The thermometers are not faulty). What further procedure is needed in the experiment to reduce the discrepancy between the two readings?
Solution:
Let T be the melting point of sulphur.
The triple point of water,T t r = 273.16 K
For thermometerA : P t r = 1.25 × 10 5 P a
P = 1.797 × 10 5 P a
∴ T A =
× t r =
× 273.16 = 392.69 K
For thermometerB : P t r = 0.200 × 10 5 P a
P = 0.287 × 10 5 P a
T B =
× T t r =
× 273.16 = 391.98 K
(b) The discrepancy arises because the gases are not perfectly ideal. To reduce the discrepancy, readings should be taken at lower pressure as in that case, the gases approach to the ideal gas behaviour.
The triple point of water,
For thermometer
For thermometer
(b) The discrepancy arises because the gases are not perfectly ideal. To reduce the discrepancy, readings should be taken at lower pressure as in that case, the gases approach to the ideal gas behaviour.
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