Answer :
The required elemental gas which has a mass of 10.3 g in the given conditions is helium gas.
How do we calculate molar mass?
Relation between the molar mass and moles of any substance will be represented as:
n = W/M, where
- W = given mass
- M = molar mass
Moles of gas will be calculated by using the ideal gas equation:
PV = nRT, where
- P = pressure = 758 torr
- V = volume = 58.4L
- n = moles = ?
- R = universal gas constant = 62.363 L.torr / K.mol
- T = temperature = 25 degree C = 298K
On putting all values, we get moles
n = (758)(58.4) / (62.363)(298) = 44,267.2 / 18,584.2
n = 2.38 moles
Molar mass of the gas will be calculated by using the above first equation is:
M = 10.3g / 2.38mol = 4.32 g/mol = 4g/mol (approx)
Hence given elemental gas is helium.
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