Pressure exerted by saturated water vapour is called aqueous tension. What correction term will you apply to the total pressure to obtain pressure of dry gas?
Whenever a gas is collected over water, it is moist and saturated with water vapours which exert their own pressure. The pressure due to water vapours is called aqueous tension thus, the to tal pressure of the gas ( $p$ moist gas) is
$$p_{\text {moist gas }}=p_{\text {dry gas }}+\text { aqueous tension }$$
Thus, $p_{\text {dry gas }}$ is given as
$P_{\text {dry gas }}=P_{\text {moist gas }}-$ aqueous tension Hence, the correction term applied to the total pressure of the gas in order to obtain pressure of dry gas is $p$ moist gas - aqueous tension.
Name the energy which arises due to motion of atoms or molecules in a body. How is this energy affected when the temperature is increased?
The energy which arises due to motion of atoms or molecules in a body is known as thermal energy. It is a measure of average kinetic energy of the particles. It increases with increase in temperature.
Name two intermolecular forces that exist between HF molecules in liquid state.
H-F is a polar covalent molecule in which dipole-dipole interactions exists. Since, it contains an electronegative atom, F bonded to H atom, therefore, H -bond exists between its molecules. Due to these H -bonds, -HF molecules exists in liquid state. Hence, in liquid state, H -bonds as well as dipole dipole interactions exists within HF molecules.
One of the assumptions of kinetic theory of gases is that there is no force of attraction between the molecules of a gas. State and explain the evidence that shows that the assumption is not applicable for real gases.
Real gases can be liquefied by cooling and compressing the gas. This proves that force of attraction exist among the molecules.
Compressibility factor, $Z$ of a gas is given as $Z=\frac{p V}{n R T}$
(i) What is the value of $Z$ for an ideal gas?
(ii) For real gas what will be the effect on value of $Z$ above Boyle's temperature?
(i) For ideal gas, compressibility factor, $Z=1$.
(ii) Above Boyle's temperature, real gases show positive deviation.
So, $$Z>1$$