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, $$Z>1$$
The critical temperature $\left(T_c\right)$ and critical pressure $\left(p_c\right)$ of $\mathrm{CO}_2$ are $30.98^{\circ} \mathrm{C}$ and 73 atm respectively. Can $\mathrm{CO}_2(\mathrm{~g})$ be liquefied at $32^{\circ} \mathrm{C}$ and 80 atm pressure?
The given critical temperature and pressure of $\mathrm{CO}_2$ gas are $30.98^{\circ} \mathrm{C}$ and 73 atm respectively. This suggests that $\mathrm{CO}_2$ gas cannot be liquified above $30.98^{\circ} \mathrm{C}$ and 73 atm hewsoever high temperature and pressure may be applied on $\mathrm{CO}_2$ gas. Hence, $\mathrm{CO}_2$ gas cannot be liquified at $32 .{ }^{\circ} \mathrm{C}$ and 80 atm .