Question

Water has a boiling point of 202oF in Denver, Colorado. What is the local absolute pressure?

Answer 1

We are assuming that Boiling point of water has changed due to change in Atmospheric pressure only. We are assuming that there is no impurities in water to effect its Boiling point.

Boiling point of Water is 100C (212F or 373K) at atmospheric pressure 1 atm = 1.013 * 10⁵ N/m²

Boiling Point of water in Denver is 202 F = (202-32)/1.8 = 94.44 C or 367.44 Kelvin

Now, we can use Claussius Clapeyron equation for boiling point at different pressure.

ln(P₂/P₁) = (ΔH_v / R) * (1/T₁ - 1/T₂) ;where ΔH_v = 40660 J/mol, R = 8.314 J/mol-K

P₂ = P₁ * e^{(ΔH_v / R) * (1/T₁ - 1/T₂)}

P₂ = (1.013 * 10⁵) * e^{(40660/8.314)* (1/373 - 1/367.44)}

P₂ = (1.013 * 10⁵) * 0.82

So, Pressure is 0.82 atm or 0.83 * 10⁵ N/m²