a 108ml sampl of gas has a mass of 77.96mg at a pressure of 1140mmhg and temperature of 183°c .what is the molar mass of the gas ?

Molar mass = 20 g/mol

Explanation:

Given data:

Volume of gas = 108 mL

Mass of gas = 77.96 mg (77.96/1000 = 0.08 g)

Pressure of gas = 1140 mmHg

Temperature of gas = 183°C

Molar mass of gas = ?

Solution:

First of all we will calculate the number of moles of gas.

PV = nRT

R = general gas constant = 0.0821 atm.L/ mol.K

Now we will convert the units and then we will put the values in formula.

Volume of gas = 108 mL× 1 L/1000 mL= 0.108 L

Pressure of gas = 1140 mmHg× 1 atm / 760 mmHg = 1.5 atm

Temperature of gas = 183+273 = 456 K

PV = nRT

1.5 atm ×0.108 L = n × 0.0821 atm.L/ mol.K ×456 K

0.162 atm.L =  n ×37.44 atm.L/ mol

n = 0.162 atm.L/37.44 atm.L/ mol

n = 0.004 mol

Molar mass of gas:

Number of moles = mass/molar mass

0.004 mol = 0.08 g / molar mass

Molar mass = 0.08 g /0.004 mol

Molar mass = 20 g/mol

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8