Question

At what temperature ammonia condenses from gaseous form into a liquid, at a pressure of 1.5 bars. I know that at normal 1 bar pressure, ammonia is a liquid between -78 and -33 degrees Celsius, but don’t know the math to work out what the temperature would be at 1.5 bars?

Answer 1

The temperature at which ammonia condenses from gaseous form into a liquid at a pressure of 1.5 bars can be approximated to be 246.5 K, using the Clausius-Clapeyron equation.

Step-by-step explanation:

The boiling point of ammonia at 1 bar pressure is -33 °C. To determine the temperature at 1.5 bars, we can use the Clausius-Clapeyron equation, which relates the boiling point of a substance to its vapor pressure. The equation is given by:

ln(P2/P1) = ∆Hvap/R * (1/T1 - 1/T2)

Where P1 and P2 are the initial and final pressures, ∆Hvap is the enthalpy of vaporization, R is the ideal gas constant, T1 is the initial temperature in Kelvin, and T2 is the final temperature in Kelvin.

In this case, we have P1 = 1 bar, P2 = 1.5 bars, T1 = -33 °C + 273.15 = 240.15 K, and we want to solve for T2.

Plugging these values into the equation, we can rearrange to solve for T2:

T2 = (ln(P2/P1) * R/(∆Hvap)) * (1/T1) + 1/T1

Using the given values of ln(P2/P1) = ln(1.5/1) = 0.405, ∆Hvap = 1.37 x 10^6 J/kg, and R = 8.314 J/(mol K), we can calculate T2 to be approximately 246.5 K.