question_answer 5)

Two ideal gas thermometers A and B use oxygen and hydrogen respectively. The following observations are made Temperature Pressure thermometer A Pressure thermometer B Triple point of water \[\therefore \] \[\vartriangle V=V-V'=M\left( \frac{1}{P}-\frac{1}{P'} \right)\] Normal melting point of sulphur \[\therefore \] \[\frac{\vartriangle V}{V}=M\left( \frac{1}{P}-\frac{1}{P'} \right)\] (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 for the slightly different answers from A and B? (The thermometers are not faulty). What further procedure is needed in the experiment to reduce the discrepancy between the two readings.

Answer:

Let T be the melting point of sulphur. For water,\[\times \frac{P}{M}=1-\frac{P}{P'}\] For Thermometer A \[\frac{\vartriangle V}{V}=1-\frac{1\cdot 03\times {{10}^{3}}}{P'}\] For Thermometer B \[B=\frac{pV}{\vartriangle V}\] (b) The cause of slight different answers is that the oxygen and hydrogen gases are not perfectly ideal. To reduce this discrepancy, the readings should be taken at lower and lower pressures as in that case, the gases approach to the ideal gas behaviour.