Question

What is the number of moles in 9.63 L of `H_2S` gas at STP?

Answer 1

0.430 mol (rounded with significant figures)

Explanation:

Any gas, at STP, will have 22.4 L per mol. Taking this into account, using dimensional analysis:

`9.63 L H_2S * (1 mol H_2S)/(22.4 L H_2S)`

`(9.63 L H_2S)/(22.4 L H_2S)=0.4299 mol`

Which rounds to 0.430 mol, with three significant figures

Answer 2

`P.V=n.R.T`

Explanation:

Use the ideal gas equation

`P.V=n.R.T`

Solve for `n`,

`n=( P*V)/(R.T)`

`P" is the pressure of the gas (" atm")"`
`V" is the volume of the gas ("L")"`
`T" is the Kelvin temperature ("K")"`
`R" is the universal gas constant ("0.0821L.\atm.mol^-1.K^-1")"`

`n=(1.00*atm*9.63*L) /(0.0821*L*atm*mol.^-1*K^-1*273*K`

`n=(1.00*cancel(atm)*9.63*cancel(L)) /(0.0821*cancel(L)* cancel(atm)*mol.^-1*cancel(K^-1)*273*cancel(K)`

`n=0.430* mol.`