Question

A sealed glass jar has a small amount of water on the bottom. The rest of the volume in the jar is taken up by helium gas at a partial pressure of 526 mmHg, and water vapor. If the total pressure inside the jar is 760. mmHg, what is the temperature of the water?

Answer 1

The temperature of the water is 70°C

Step-by-step explanation:

Partial pressure of helium gas = 526 mmHg

Total pressure inside the jar= 760 mmHg

Suppose partial pressure of helium gas is
`P_H_e` and partial pressure of water is
`P_H__2O`

And total pressure is
`P_T`

As we know

`\mathrm{P}_{\mathrm{T}}=\mathrm{P}_{\mathrm{HE}}+\mathrm{P}_{\mathrm{H} 2 \mathrm{O}}`

Hence

Putting the values

`760=526+\mathrm{P}_{\mathrm{H} 2 \mathrm{O}}`

`\mathrm{P}_{\mathrm{H} 2 \mathrm{O}}=760-526`

`\mathrm{P}_{\mathrm{H} 20}=234 \mathrm{mm} \mathrm{Hg}`

In bar,

`\mathrm{P}_{\mathrm{H} 2 \mathrm{O}}=234 \mathrm{mm} \mathrm{Hg} * \frac{1.01325 \mathrm{bar}}{760 \mathrm{mm} \mathrm{Hg}}`

= 0.312 bar

Now according to the steam table

With the vapour pressure of water as 0.312 bar the temperature corresponds to 70°C