Question

Question 1 You want to reach a high boiling point in an aqueous system, so you increase the pressure in the reaction flask. You find that the water boils at a temperature of 212.6 °C. What is the pressure in the reaction flask, in atmospheres? (Given: AH°vap(H20) = 43.4 kJ/mol) (Please answer to 2 decimal places, just to keep Brightspace happy, no matter what the sig figs should be!

Answer 1

To determine the pressure in the reaction flask, we can use the Clausius-Clapeyron equation, which relates the boiling point of a substance to its enthalpy of vaporization and the pressure.

The Clausius-Clapeyron equation is given by:

ln(P2/P1) = (ΔHvap/R) * (1/T1 - 1/T2)

Where:
P1 is the initial pressure (1 atm)
P2 is the final pressure (to be determined)
ΔHvap is the enthalpy of vaporization (43.4 kJ/mol)
R is the ideal gas constant (0.0821 L·atm/(mol·K))
T1 is the initial temperature (in Kelvin)
T2 is the final temperature (in Kelvin)

Given:
T1 = 100 °C = 373.15 K (boiling point of water at 1 atm)
T2 = 212.6 °C = 485.75 K
ΔHvap = 43.4 kJ/mol
P1 = 1 atm

Step-by-step solution:

1. Convert ΔHvap from kJ/mol to J/mol:
ΔHvap = 43.4 kJ/mol * 1000 J/kJ = 43,400 J/mol

2. Convert temperatures to Kelvin:
T1 = 373.15 K
T2 = 485.75 K

3. Plug in the values into the Clausius-Clapeyron equation:
ln(P2/1) = (43,400 J/mol / (0.0821 L·atm/(mol·K))) * (1/373.15 - 1/485.75)

4. Solve for ln(P2/1):
ln(P2/1) = (43,400 J/mol / (0.0821 L·atm/(mol·K))) * (0.002680 - 0.002058)

5. Calculate P2/1 by taking the exponential of both sides of the equation:
P2/1 = e^((43,400 J/mol / (0.0821 L·atm/(mol·K))) * (0.002680 - 0.002058))

6. Calculate P2 by multiplying both sides by 1 atm:
P2 = 1 atm * e^((43,400 J/mol / (0.0821 L·atm/(mol·K))) * (0.002680 - 0.002058))

Now, apply the calculations to find the pressure in the reaction flask.