Question

Carbon dioxide, when it is at -145 degreesC has a density of 2.54 g/L. What is the pressure in torr??

Answer 1

Answer: The pressure in torr is 461 torr

Explanation:

To calculate the relation of density and molar mass of a compound, we use the ideal gas equation:

PV=nRT

P = pressure

V = Volume

n = number of moles

R = gas constant = 0.0821 Latm/Kmol

T = temperature =$-145^0C=(273-145)K=128K$

Number of moles (n) can be written as:

$n=\frac{m}{M}$

where, m = given mass

M = molar mass  = 44 g/mol

$PV=\frac{m}{M}RT\\\\PM=\frac{m}{V}RT$

where,

$\frac{m}{V}=d$

where d = density = 2.54 g/L

The relation becomes:

PM=dRT  

$P=\frac{dRT}{M}$

$P=\frac{2.54\times 0.0821\times 128}{44}=0.607atm$

$P=461torr$    (760torr=1atm)

Thus the pressure in torr is 461 torr