relationship between no. of moles of gas with volume

CHAPTER 3 : CHAPTER 3 : CHEMICAL FORMULAE & CHEMICAL FORMULAE &

EQUATIONSEQUATIONS

3.4 The Mole & the Volume 3.4 The Mole & the Volume of Gasof Gas

MOLAR VOLUME

22.4 dm22.4 dm33 at at STPSTP

(0°C and 1 atm)(0°C and 1 atm)

- volume occupied by 1 - volume occupied by 1

mole of any gasmole of any gas

24 dm24 dm33 at Room at Room Conditions Conditions

(25°C and 1 atm)(25°C and 1 atm)

3.4 The Mole & the Volume of Gas3.4 The Mole & the Volume of Gas

3.4 The Mole & the Volume of Gas3.4 The Mole & the Volume of Gas

O2 gas

O2 gas

In STP In Room Condition

22.4 22.4 dmdm

33 24 dm 24 dm 33VolumVolume of Oe of O22 = =

VolumVolume of Oe of O22 = =

GENERALISATION OF GENERALISATION OF MOLAR VOLUME OF MOLAR VOLUME OF

GASESGASES

•1 mole1 mole of any gas always occupies of any gas always occupies

the the samesame volumevolume under the under the same same

temperature and pressure.temperature and pressure.

3.4 The Mole & the Volume of Gas3.4 The Mole & the Volume of Gas

No. of Moles

Volume of gas (dm3)

x molar volume

molar volume

RELATIONSHIP BETWEEN THE RELATIONSHIP BETWEEN THE NUMBER OF MOLES AND THE MASS NUMBER OF MOLES AND THE MASS

OF A SUBSTANCEOF A SUBSTANCE

3.4 The Mole & the Volume of Gas3.4 The Mole & the Volume of Gas

Examples:

Calculate the volume of 0.075 mol of carbon dioxide gas measured at STP

Find the number of moles of 4800 cm³of ammonia gas at room conditions

Try to find:

3.4 The Mole & the Volume of Gas3.4 The Mole & the Volume of Gas

No. of Moles

Volume of gas (dm3)

Mass (g)

x molar massNo. of

Particles

x NA

NA

molar x

volume

molar volume

molar mass

P/S:Number of moles act as an intermediate

No. of moles

=Mass (g)

Molar mass (Ar or Mr)

No. of moles

=Volume (dm3)

Molar volume (STP=22.4 dm3 mol-1 or

Room=24 dm3 mol-1)

No. of particles

=No. of moles x NA