Question

a natural gas has a following composition by volume methane=82%, ethylene=12% N2=6% Calculate the density of gas at 288 k and 101.325kPa and composition in weight%​

Answer 1

Answer:

DENSITY OF A GAS

Recall that the density of a gas is its mass to volume ratio,

ρ=mV

. Therefore, if we can determine the mass of some volume of a gas, we will get its density. The density of an unknown gas can used to determine its molar mass and thereby assist in its identification. The ideal gas law, PV = nRT, provides us with a means of deriving such a mathematical formula to relate the density of a gas to its volume in the proof shown in Example 1.

Example 1

Derivation of a Density Formula from the Ideal Gas Law

Use PV = nRT to derive a formula for the density of gas in g/L

Solution

PV = nRT

Rearrange to get (mol/L):

nv=PRT

Multiply each side of the equation by the molar mass, M

. When moles are multiplied by M in g/mol, g are obtained:(M)(nV)=(PRT)(M) g/L=ρ=PMRT

Check Your Learning

A gas was found to have a density of 0.0847 g/L at 17.0 °C and a pressure of 760 torr. What is its molar mass? What is the gas?

Answer:

ρ=PMRT

0.0847

g/L=760torr×1atm

760torr×M0.0821

Latm/mol K×290KM

= 2.02 g/mol; therefore, the gas must be hydrogen (H2, 2.02 g/mol)

We must specify both the temperature and the pressure of a gas when calculating its density because the number of moles of a gas (and thus the mass of the gas) in a liter changes with temperature or pressure. Gas densities are often reported at STP.

Explanation:

Hope it helps you ✌