Question

if the density of a certain gas at 30 degree Celsius and 768 store is 1.35 kg per metre cube its density at STP would be

Answer 1

I think it can be solved like this.

Hope it helps you.

Answer 2

Answer: Density of a gas at STP is 1.482 kg/L

Explanation:

Given:

$d=1.35 kg/m^3$

T = 30 °C = 273 + 30 = 303K

P = 768 torr

Using Ideal gas equation,

PV = nRT

N = number of moles and this can be written as:

$n=\frac{W}{M}$ where W and M are the given mass and molar mass respectively.

Putting value of 'n' in ideal gas equation,we get

$PV=\frac{WRT}{V}$

and $density=\frac{W}{V}$

Now, putting this in above equation, we get

$P=\frac{dRT}{M}$     ....(1)

We are given temperature, pressure and density, we can calculate Molar mass by using above equation, we get

$R=62.364\text{ L Torr }K^{-1}mol^{-1}$

$M=\frac{(1.35kg/L)(62.364\text{ L Torr }K^{-1}mol^{-1})(303K)}{768Torr}$

M = 33.216 kg/mol

Now, to calculate density at STP, conditions are:

P = 1 atm

$R=0.082057\text{ L atm }mol^{-1}K^{-1}$

T = 273 K

M = 33.216 kg/mol (calculated above)

Density is calculated by using the equation 1, we get

$d=\frac{PM}{RT}=\frac{(1atm)(33.216kg/mol)}{(0.082057\text{ L atm }mol^{-1}K^{-1})(273k)}$

d = 1.482 kg/L