Answer: The boiling point of water at 81 kPa will be 298.17 K.
Explanation:
The boiling point of water is 373 K at atmospheric pressure. So, to calculate the boiling point at 81 kPa, we use the law given by Gay-Lussac.
Gay-Lussac Law states that pressure is directly proportional to the temperature when volume and moles remain constant.
Mathematically,
[tex]\frac{P_1}{T_1}=\frac{P_2}{T_2[/tex]
where,
[tex]P_1\text{ and }T_1[/tex] = Initial pressure and temperature
[tex]P_2\text{ and }T_2[/tex] = Final pressure and temperature
We are given:
[tex]P_1=1atm=101.325kPa\\T_1=373K\\P_2=81kPa\\T_2=?K[/tex]
Putting values in above equation, we get:
[tex]\frac{101.325kPa}{373K}=\frac{81kPa}{T_2}\\\\T_2=298.17K[/tex]
Hence, the boiling point of water at 81 kPa will be 298.17 K.
