(a) State two postulates of the kinetic theory of... | WAEC SSCE - Chemistry - 1998

Question 1 Report

(a) State two postulates of the kinetic theory of gases.

(b) Write two chemical properties that are common to both carbon (IV) oxide and sulphur (IV) oxide.

Answer

(a) Two postulates of the kinetic theory of gases:

A gas consists of a very large number of tiny particles (molecules) which are in continuous, rapid, random motion.
The actual volume of the gas particles is negligible compared with the total volume of the container (there is a lot of empty space between them). (Also acceptable: there are negligible forces of attraction between the particles, and collisions between them are perfectly elastic; the average kinetic energy is proportional to the absolute temperature.)

(b) Two chemical properties common to both carbon(IV) oxide, \(CO_2\), and sulphur(IV) oxide, \(SO_2\):

Both are acidic oxides: they dissolve in water to form acids (\(CO_2\) forms trioxocarbonate(IV) acid, \(SO_2\) forms trioxosulphate(IV) acid) and turn moist blue litmus red.
Both react with alkalis (bases) to form salt and water, e.g. \(CO_2 + 2NaOH \rightarrow Na_2CO_3 + H_2O\) and \(SO_2 + 2NaOH \rightarrow Na_2SO_3 + H_2O\). (Both are also non-supporters of combustion.)

Answer Details

(a) Two postulates of the kinetic theory of gases:

A gas consists of a very large number of tiny particles (molecules) which are in continuous, rapid, random motion.
The actual volume of the gas particles is negligible compared with the total volume of the container (there is a lot of empty space between them). (Also acceptable: there are negligible forces of attraction between the particles, and collisions between them are perfectly elastic; the average kinetic energy is proportional to the absolute temperature.)

(b) Two chemical properties common to both carbon(IV) oxide, \(CO_2\), and sulphur(IV) oxide, \(SO_2\):

Both are acidic oxides: they dissolve in water to form acids (\(CO_2\) forms trioxocarbonate(IV) acid, \(SO_2\) forms trioxosulphate(IV) acid) and turn moist blue litmus red.
Both react with alkalis (bases) to form salt and water, e.g. \(CO_2 + 2NaOH \rightarrow Na_2CO_3 + H_2O\) and \(SO_2 + 2NaOH \rightarrow Na_2SO_3 + H_2O\). (Both are also non-supporters of combustion.)

(a) State two postulates of the kinetic theory of gases. (b) Write two chemical properties that are common to both carbon (IV) oxide and sulphur (IV) oxide.