Hey there!
<span>Use the equation of Clapeyron:
</span>
T in kelvin :
26 + 273.15 => 299.15 K
R = 0.082
V = 10.2 L
P = 0.98 atm
number of moles :
P *V = n * R * T
0.98 * 10.2 = n * 0.082 * 299.15
9.996 = n * 24.5303
n = 9.996 / 24.5303
n = 0.4074 moles
Therefore:
Molar mass H2O = 18.01 g/mol
1 mole H2O ------------- 18.01 g
0.4074 moles ----------- m
m = 0.4074 * 18.01 / 1
m = 7.339 g of H2O
This is a Physical change. No chemistry involved.
Divide the mass of the compound in grams by the molar mass you just calculated. The answer is the number of moles of that mass of compound.
I hope it helps