Question

Calculate the molar mass of a gas

with 0.4 g mass and 280 mL of
volume at standard temperature
and pressure (STP).​

Answer 1

MOLAR MASS = 32 g/mol

Step-by-step explanation:

Condition of standard temperature and pressure(STP) are as follow:

Temperature = 273 K

Pressure = 1 atm (or 100000 Pa)

Here atm is atmosphere and Pa is Pascal

STP conditions arte used for measuring gas density and volume using Ideal Gas Law.Here 1 mole of ideal gas occupies 22.4 L of volume.

According toi Ideal Gas Equation :

PV = nRT

where P = pressure, n= number of moles, V = volume ,R= Ideal Gas Constant and T= temperature

`n=(PV)/(RT)`

From question:

V=280 ml = 0.28 L

P = 1 atm

R=0.08205 L atm/K mol

T=273 K

Putting values in above formula :

`n=(1* .280)/(0.08205* 273)`

n = 0.0125 moles

Now
`n=(given\ mass)/(Molar\ mass)`

`<strong>Molar\ mass=(given\ mass)/(n)</strong>`

given mass = 0.4 g (given)

`<strong>Molar\ mass=(0.4)/(0.0125)</strong>`

On solving we get:

Molar mass = 32 g/mol