Physics · Heat, temperature, thermal expansion, specific heat capacity, calorimetry, change of state, latent heat

Mercury boils at . However mercury thermometers are made such that they can meas

Mercury boils at \( 356^{\circ} \mathrm{C} \). However mercury thermometers are made such that they can measure temperatures up to \( 500^{\circ} \mathrm{C} \). This is done by :

  • A. maintaining vacuum above the mercury column in the steam of the thermometer
  • B. filling nitrogen gas at high pressure above the mercury column
  • C. filling nitrogen gas at low pressure above the mercury column
  • D. filling oxygen gas at high pressure above the mercury column

Step-by-step solution

Mercury boils at 356°C, but to measure temperatures up to 500°C, the boiling point must be raised. According to the Clausius-Clapeyron relation, increasing the pressure above the mercury column elevates its boiling point. Nitrogen gas at high pressure is used because it is inert and does not react with mercury, allowing the thermometer to function at higher temperatures.
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