Two ideal gas thermometers Aand Buse oxygen and hydrogen respectively. The following observations are made:

Temperature

Pressure thermometer A

Pressure thermometer B

Triple-point of water

1.250 × 10⁵ Pa

0.200 × 10⁵ Pa

Normal melting point of sulphur

1.797 × 10⁵ Pa

0.287 × 10⁵ Pa

(a) What is the absolute temperature of normal melting point of sulphur as read by thermometers Aand B?

(b) What do you think is the reason behind the slight difference in answers of thermometers Aand B? (The thermometers are not faulty). What further procedure is needed in the experiment to reduce the discrepancy between the two readings?

Open in App

Solution

(a) Triple point of water, T = 273.16 K.

At this temperature, pressure in thermometer A, P_A = 1.250 × 10⁵ Pa

Let T₁ be the normal melting point of sulphur.

At this temperature, pressure in thermometer A, P₁ = 1.797 × 10⁵ Pa

According to Charles’ law, we have the relation:

= 392.69 K

Therefore, the absolute temperature of the normal melting point of sulphur as read by thermometer A is 392.69 K.

At triple point 273.16 K, the pressure in thermometer B, P_B = 0.200 × 10⁵ Pa

At temperature T₁, the pressure in thermometer B, P₂ = 0.287 × 10⁵ Pa

According to Charles’ law, we can write the relation:

Therefore, the absolute temperature of the normal melting point of sulphur as read by thermometer B is 391.98 K.

(b) The oxygen and hydrogen gas present in thermometers A and B respectively are not perfect ideal gases. Hence, there is a slight difference between the readings of thermometers A and B.

To reduce the discrepancy between the two readings, the experiment should be carried under low pressure conditions. At low pressure, these gases behave as perfect ideal gases.

Suggest Corrections

Similar questions

The ideal gas law, which relates the P, V and temperature T of an ideal gas in a closed box, given as PV = nRT, can be manipulated to construct an effective thermometer. A "constant volume gas thermometer” uses a sample of gas (commonly, nitrogen or helium) in a closed chamber, thus fixing the volume V. The temperature is then measured by reading off the corresponding pressure P. At the freezing point of water, it is seen that a gas thermometer records a pressure of 0.9 x 10⁵ Pa; it also records a pressure of 1.2 x 10⁵ Pa at the boiling point of water. What pressure will you find in the gas chamber at a room temperature of 23⁰C?

Q. A gas thermometer is used as a standard thermometer for measurement of temperature. When the gas container of the thermometer is immersed in water at its triple point

273.16

K, the pressure in the gas thermometer reads

3.0 \times 10^{4}

N / m^{2}

. When the gas container of the same thermometer is immersed in another system, the gas pressure reads

3.5 \times 10^{4}

N / m^{2}

. The temperature of this system is therefore __________

^{o} C

Q. A thermometer has wrong calibrations. It reads melting point of ice as

- 10^{o} C

and reads

60^{o} C

at temperature of

50^{o} C

. Temperature of boiling point noted by this thermometer will be (All temperature are note d atmospheric pressure)

Q. A Kelvin thermometer and a Fahrenheit thermometer used to record temperature of a melting metal are showing the same reading. What will a Celsius thermometer read at that temperature?

Q. The upper and lower fixed points of a faulty mercury thermometer are

210^{o} F

and

34^{o} F

respectively. The correct temperature read by this thermometer is

Join BYJU'S Learning Program

Temperature	Pressure thermometer A	Pressure thermometer B
Triple-point of water	1.250 × 10⁵ Pa	0.200 × 10⁵ Pa
Normal melting point of sulphur	1.797 × 10⁵ Pa	0.287 × 10⁵ Pa