Calculated how many grams of methane are in a sealed 80 mL flask at room temperature (22ºC) and 780 mm Hg?

Answer 1

To solve this problem, you will need to use the general gas equation (its my favourite equation!) ie

PV = nRT

where
P = pressure
V = volume
n = number of moles
R = Universal Gas Constant
T = Temperature

Having calculated the number of moles from above, you can then find the mass using

n = m/MM

where
m = mass (g)
MM = molar mass (gmol^-1)

If you need more help than that, please re post or email me.

Answer 2

0.05439 g.