- #1

CAF123

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## Homework Statement

The ideal gas law states that 1 mole of an ideal gas at 0°C and 1 atmosphere=1.0125x105Pa (standard temperature and pressure, or “STP”) occupies a volume of 22.4litres (2.24x10-2m3).

(i) Use this result to obtain an approximate value for the increase in volume that occurs when a mass of water at 100°C is converted into steam at the same temperature.

For argon (monatomic gas, mass=40amu) at STP, estimate:

(ii) The typical spacing between atoms

(iii) The root-mean-square (rms) speed of the atoms

## The Attempt at a Solution

i)I am not sure how to use the ideal gas law STP conditions. For one, this assumes 0 degrees temperature, while the question is concerned with 100 degrees. I know I have to incorporate the latent heat of vapourisation since the water is changing phase. (and at the same temperature)

ii) Assuming small spherical atoms, ##r = \left(\frac{6}{\pi n}\right)^{1/3}##, where n = N_a/V, but I think this just takes me in a circle since I don't know V. Also, I think I have to assume ideal gas conditions, so each particle would be of negligible volume.

Many thanks.