Molar Volume of Gas, VMolar Volume of Gas, VMM

Molar gas is defined as the volume Molar gas is defined as the volume occupies by one mole of the gas.occupies by one mole of the gas.

At S.T.P condition:At S.T.P condition: Molar Volume of aMolar Volume of a gas is 22.4 dm gas is 22.4 dm33

At Room condition:At Room condition: Molar Volume of aMolar Volume of a gas is 24 dm gas is 24 dm33

Molar Volume of a GasMolar Volume of a Gas

Note :Note : 1 dm 1 dm3 3 = 1000 cm= 1000 cm33

22.4 dm22.4 dm3 3 = 22 400 cm= 22 400 cm33

24 dm24 dm3 3 = 24 000 cm= 24 000 cm33

S.T.P. conditionS.T.P. condition [ temperature 0[ temperature 0°C, Pressure 1 atmosfera or 101kPa ]°C, Pressure 1 atmosfera or 101kPa ]

Room condition :Room condition :

[temperature 25[temperature 25°C, Pressure 1 atmosfera atau 101kPa ]°C, Pressure 1 atmosfera atau 101kPa ]

Conversion of Conversion of Mol and Volume of Gas Mol and Volume of Gas

Moles of Moles of GasGas

Volume of Volume of Gas (dmGas (dm33))

Molar Volume

Molar Volume

Example of Calculation I

Calculate the volume of gas occupies by 0.2 mol of ethene gas , C2H4 at S.T.P..

[ molar volume of gas : 22.4dm3mol–1 at S.T.P.]

Volume of C2H4 gas = mol × molar volume of gas

= 0.2 × 22.4 dm3

= 4.48 dm3

Example of Calculation II

A balloon contains 12.0cm3 of helium gas, He at room condition. How many moles of helium is in the balloon?

[Molar Volume of gas : 24dm3mol–1 at room condition]

mol0005.0molcm24000

cm12

moldm24

cm0.12

gasofvolumeMolar

heliumofvolumegasHeofMol

13

3

13

3

Conversion of Conversion of Mole , Number of Particles, Mass and Mole , Number of Particles, Mass and Volume of Gas Volume of Gas

Mole (n)

Of Gas

Volume (V)

Of Gas

Mv

Mv

Mass (m)

of Gas

Number of Particles Number of Particles (N) Gas(N) Gas

Mm

Mm

NA NA

Example of Calculation 1

What is the volume of hydrogen that contain in 0.6 g of gas hidrogen at STP?

[ AR : H, 1 ; Molar Volume of gas : 22.4dm3mol–1 at STP]

Volume of H2 gas = mol × molar volume of gas

3

3

2

2

dm72.6

dm4.22)1(2

6.0

gasofvolumemolarHmassMolar

HofMass

Example of Calculation 2

A sample of monoatom gas P contains 1.505 ×1022 of atom. What is the volume of P gas at room condition?

[Avogadro Constant, NA = 6.02× 1023 ; molar volume of gas : 24dm3mol–1 at room condition.]

Volume of P gas = mol × molar volume of gas

3

323

22

A

dm6.0

dm241002.6

10505.1

gasofvolumemolarN

atomPgasofNumber

Example of Calculation 3

How many molecules are there in 8.96dm3 of sulphur dioxide at S.T.P.?

[Avogadro Constant, NA = 6.02× 1023 ; Molar Volume of gas : 22.4dm3mol–1 at S.T.P. condition]

Number of SO2 molecules = mole × NA

molecules10408.2

1002.64.22

96.8

NVolumeMolar

SOofvolume

23

23

A2