Home
Class 11
CHEMISTRY
34.05 mL of phosphorus vapour weights 0....

34.05 mL of phosphorus vapour weights 0.0625 g at `546^(@)C` and 1 bar pressure. What is the molar mass of phosphorus ?

Text Solution

Verified by Experts

According to ideal gas law,
`pV=nRT=(w)/(M)RT`
`therefore M=(wRT)/(pV)`
where,
Molecular mass of phosphorus, (w) = 0.0625 g
Gas Constant `(R )=8.314xx10^(-2)` bar `L mol^(-1)K^(-1)`
Pressure of phosphorus vapour (p) = 1.0 bar
Absolute temperature `(T)=(546+273)K=819 K`
Volume of Phosphorus vapour (V) = 34.05 mL
= 0.03405 L
`therefore M =((0.0625 g)(8.314xx10^(-2)"bar L mol"^(-1)K^(-1))(819K))/(("1 bar")(0.03405 L))`
`= 124.98 = 125 g mol^(-1)`
Note : If 0.1 bar is corrct for according to text book then answer will be 1249.8. It is not real because,
`P_(4)=31xx4=124`
Promotional Banner

Topper's Solved these Questions

  • STATES OF MATTER

    KUMAR PRAKASHAN|Exercise SECTION - A QUESTIONS (Sub Question)|3 Videos

  • STATES OF MATTER

    KUMAR PRAKASHAN|Exercise SECTION - A QUESTIONS (TRY YOUR SELF)|47 Videos

  • SOME BASIC CONCEPTS OF CHEMISTRY

    KUMAR PRAKASHAN|Exercise Section - D (Solutions of NCERT Exemplar Problems) (Long Answer Type Questions)|4 Videos

  • STRUCTURE OF ATOM

    KUMAR PRAKASHAN|Exercise QUESTINS PAPER FROM MODULE (SECTION -D)|2 Videos

Similar Questions

Explore conceptually related problems

A pure gas that is 14.3% hydrogen and 85.7% carbon by mass has a density of 2.5g L^(-1) at 0^(@)C and 1 atm pressure. What is the molecular formula of the gas :

The vapor pressure of acetone at 20^(@)C is 185 torr. When 1.2 g of a non-volatile solute was dissolved in 100 g of acetone at 20^(@)C , it vapour pressure was 183 torr. The molar mass (g mol^(-1)) of solute is:

The vapour pressure of pure benzene at a certain temperature is 640 mm Hg . A non-volatile solid weighing 2.175g is added to 39.0g of benzene. The vapour pressure of the solution is 600mm Hg . What is the molar mass of the solid substance?

A solution containing 30g of a nonvolatile solute in exactly 90g water has a vapour pressure of 21.85 mm Hg at 25^(@)C . Further 18g of water is then added to the solution. The resulting solution has vapour pressure of 22.18 mm Hg at 25^(@)C . calculate (a) molar mass of the solute, and (b) vapour pressure of water at 25^(@)C .