Answer:
P₁ = 0.0562 atm
Explanation:
Using the Clausius-Clapeyon equation
ln (P₁ / P₂) = ΔHvap/R (1/T₂ - 1/T₁) ------ (eqn 1)
Step 1: From the question given, we state out the parameters given
P₁ = ? T₁ = -148.0⁰C
P₂ = 1atm T₂ = -108.0⁰C
ΔHvap = 12.6kJ/mol R = 8.314J/K.mol
Step 2: Do conversions where necessary for unit consistency since our R value is in J/K.mol
a) convert ⁰C to K
1K = ⁰C + 273.15
T₁ = -148.0⁰C => -148.0⁰C + 273.15
T₁ = 125.15K
T₂ = -108.0⁰C => -108.0⁰C + 273.15
T₂ = 166.15K
b) convert kJ/mol to Joules
ΔHvap = 12.6kJ/mol = 12600Joules
substituting parameters into eqn 1
ln (P₁ / P₂) = ΔHvap/R (1/T₂ - 1/T₁)
ln (P₁/1atm) = 12600J / 8.314 (1/166.15 - 1/125.15)
= 1515.51 (0.0060 - 0.0079)
= 1515.51(-0.0019)
ln (P₁/1atm) = -2.8794
taking exponential of both sides to get rid of the natural log
P₁ = e^ -2.8794
P₁ = 0.05616 atm
P₁ = 0.0562atm
Key Words
1) Clausius-Clapeyon: shows the relationship between pressure and temperature and it is used to estimate the vapour of a solution at a different temperature
