Gas Laws: Avogadro’s, Gay Lussac’s law of combining volumes, Graham’s law of diffusion

CONTENT

• Avogadro’s law
• Gay lussac’s law of combining volumes
• Graham’s law of diffusion

AVOGADRO’S LAW

This law states that equal volume of all gases at the same temperature and pressure contain the same number of molecules. This means that 1 mole of any gas at s.t.p has a volume of 22.4dm³.

GAY LUSSAC’S LAW OF COMBINING VOLUMES

It states that when gases react they do so in volumes which are simple ratios to one another and to the volumes of the products if gaseous, provided that the temperature and pressure remain constant.

EVALUATION

1. State the Gay Lussac’s law of combining volumes
2. 40cm³ of hydrogen was sparked with 160cm³ of oxygen at 100^oC and 1atm. Determine the volume of oxygen left after the reaction.

GRAHAM’S LAW OF DIFFUSION

It states that the rate of diffusion of a gas is inversely proportional to the square root of its density at constant temperature and pressure.

GENERAL EVALUATION/REVISION

1. State Graham’s law of diffusion
2. Under the same condition of temperature and pressure, hydrogen diffuses 8 times as     fast as gas Y. Calculate the relative molecular mass of Y.
3. State the following rule/principle: (a) Hund’s rule of maximum multiplicity (b) Aufbau principle
4. Write the electronic configuration of (a) oxide ion, (b) Aluminium ion,  (c) potassium (d) phosphorus.

READING ASSIGNMENT

New School Chemistry for Senior Secondary School by O.Y. Ababio, Pg 86-92

WEEKENDASSIGNMENT

1. 400cm³ of a gas X diffuses through a porous pot in 2 minutes. Calculate the rate at which X diffuses. A. 6.3cm³s^-1B. 20cm³s^-1 C. 200cm³s^-1D. 3.33cm³s^-1#
2. The relationship between the density (d) of a gas and the rate at which the gas diffuses is A. R = kd

B. R= k/√d C. R = k√d D. k/d

• Calculate the minimum volume of oxygen required for the complete combustion of a mixture of 20cm³ CO and 20cm³ of H₂. A. 10cm³B. 20cm³C. 40cm³D. 60cm³
• If sulphur (iv) oxide and methane (CH₄) are released at the same time at opposite ends of a tube, the rate of diffusion will be in the ratio A. 2:1 B. 4:1 C. 1:4 D. 1:2
• ‘Equal volume of all gases at the same temperature and pressure contain same number of molecules’ is a state of which law A. Avogadro’s law B. Boyle’s lawC. Charles’ law      D. Chemical law

THEORY

1. Arrange the following gases in order of increasing rate of diffusion: CO, SO₂, H₂S,NO₂ and O₂.
2. The vapour densities of O₂ and Cl₂ are 16 and 36 respectively. If 60cm³ of O₂ diffuses through a porous partition in 14 seconds, how long will it take 1000cm³ of Cl₂ to diffuse through the same partition?