Step 1
Water is supposed to be in the gas phase and it is assumed that it is an ideal gas.
Therefore, it can be applied:
p x V = n x R x T (1)
p = pressure = 6.32 atm
V = volume = 39.2 L
n = moles = unknown
R = gas constant = 0.082 atm L/mol K
T = absolute temperature = 486 °C + 273 = 759 K
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Step 2
n is cleared from (1):
p x V/R x T = n
(6.32 atm x 39.2 L)/(0.082 atm L/mol K x 759 K) = n
3.98 moles = n
Answer: number of moles = 3.98 moles
