In a constant volume gas thermometer, the pressure of the working gas is measured by the difference in the levels of mercury in the two arms of a U-tube connected to the gas at one end. When the bulb is placed at the room temperature 27.0℃, the mercury column in the arm open to atmosphere stands 5.00 cms above the level of mercury in the other arm. When the bulb is placed in a hot liquid, the difference of mercury levels becomes 45.0 cms. Calculate the temperature of the liquid. (Atmospheric pressure = 75.0 cm of mercury.)
177℃
The pressure of the gas = atmospheric pressure + the pressure due to the difference in mercury levels
At 27℃, the pressure is (75 cm + 5 cm) = 80 cm of mercury. At the liquid's temperature, the pressure is (75 cm + 45 cm) = 120 cm of mercury
Using T2=(P2P1)T1, the temperature of the liquid is -
T=[(12080)×(27.0+273.15)]K=450.22 K=177.07∘C≈177∘C.