Question

A 1L flask contains 32g of O2 gas at 27°C. What mass of O2 must be released to reduce the pressure in flask to 12.315

Answer 1

Released mass of oxygen is 16 g/mol

Explanation:

Initial mass of oxygen $M_{1}$= 32 g

Temperature , T = $27^{0} \mathrm{C}$ = (27 + 273) = 300 K

Volume of flask = 1L

Pressure of gas reduced P = 12.315 atm

An ideal gas equation $P V=n R T$

Rearrange the equation is as follows.

$n=\frac{P V}{R T}$

$=\frac{12.315 \times 1}{0.0082 \times 300}$

=0.5 moles

Hence, number of moles of oxygen = 0.5

One mole of oxygen has 32 g/mol

For 0,5 mole of oxygen will be 16 g/mol

Mass of released oxygen = 32 -16 = 16 gm .