<u>Answer:</u> The vapor pressure of naphthalene in the flask is atm.
<u>Explanation:</u>
For the conversion of naphthalene solid to naphthalene gas, the equilibrium reaction follows:
- The equation used to calculate enthalpy change is of a reaction is:
The equation for the enthalpy change of the above reaction is:
We are given:
Putting values in above equation, we get:
- The equation used to calculate gibbs free change is of a reaction is:
The equation for the enthalpy change of the above reaction is:
We are given:
Putting values in above equation, we get:
- To calculate the (at 25°C) for given value of Gibbs free energy, we use the relation:
where,
= Gibbs free energy = 22.5 kJ/mol = 22500 J/mol (Conversion factor: 1kJ = 1000J)
R = Gas constant =
T = temperature =
= equilibrium constant at 25°C = ?
Putting values in above equation, we get:
- To calculate the equilibrium constant at 35°C, we use the equation given by Arrhenius, which is:
where,
= Equilibrium constant at 35°C = ?
= Equilibrium constant at 25°C =
= Enthalpy change of the reaction = 72.1 kJ/mol = 72100 J
R = Gas constant =
= Initial temperature =
= Final temperature =
Putting values in above equation, we get:
- To calculate the partial pressure of naphthalene at 35°C, we use the expression of , which is:
Partial pressure of solid is taken as 1 at equilibrium.
So, the value of will be equal to
Hence, the partial pressure of naphthalene at 35°C is atm.