Answer:
12.0g/mole
Explanation:
Since the gas is at STP, it'll have standard values of temperature and pressure at STP
V = 22.4L
m = 12.0g
T = 273.15
P = 1.0 atm
R = 0.082 L.atm / K.mol
Using ideal gas equation,
PV = nRT
n = no. Of moles
n = PV / RT
n = (1.0 * 22.4) / (0.082 * 273.15)
n = 22.4 / 22.3983
n = 1.00
But number of moles (n) = mass (m) / molar mass (M)
n = m / M
M = m / n
M = 12.0 / 1.0
M = 12g/mol
The molar mass of the gas is 12.0g/mole
