A 2.0g sample of SX6 (g) has a volume of 329.5 cm3 at 1.00 atm and 20o C. Identify the element 'X'. Name the compound.

Volume (v) = 329 cm³*10^ (-3) litre=0.329 litre

pressure (p) = 1 atm

temperature (t) = 20°C = (20+273) K=293K

no of moles of gas=n (=m/M)

given mass=m=2 gm

universal gas constant (R) = 0.0821

molar mass (M) = ?

Using the case of ideal gas,

pv=nRt

or, 1*0.329 = (m/M) * 0.0821 * 293

or, 0.329 = (2/M) * 0.0821 * 293

or, M = (2 * 0.0821 * 293) / 0.329

M=48.1106/0.329

M=146.23 g

i. e, molar mass of SX6=146 (approx. value)

molar mass of X6=146-molar mass of S

=146-32=114 (approx.)

➡molar mass of X=114/6=19 ... which is the molar mass of fluorine (F).

So, the given compound is SF6