Question

I am having trouble with Part B!! A-- You have a solution of 0.935 m ammonium chloride (MW 53.49 g/mol). This solution was made by dissolving solid ammonium chloride in 1.00 kg of ethanol (MW 46.07g/mol). The vapor pressure of pure ethanol at 25 degrees Celsius is Pvap=55.0 mmHg. Calculate the vapor pressure for the ammonium chloride solution at 25 degrees Celcius B--Using the information in part A, calculate the vapor pressure of the solution at 55 degrees Celcius.

Answer 1

Ok. So you are in trouble with part B. So for that problem you can use Antoine's equation which is actually derived from the Clausius-Clapeyron equation. The equation is,

Where p = vapor pressure

T = temperature

A, B and C are component specific constants

Some times a simpler form of the equation is used with only two coefficients A and B.

i.e.;  

Now coming to the most important part of this question. For this particular numerical you have to know the values of A and B in the 25⁰C temperature. The values of A, B and C are given below,

A = 8.2042 mmHg

B = 1642.9 mmHg

C = 230.3 mmHg

All these above data will be valid in the temperature range of -57⁰C to 80⁰C

The values of A and B are positive for ethanol. It is clear from the equation with an increase in temperature(T) the vapor pressure(p) also increases.

Now, using the previous data you can find out the final result (vapor pressure of the solution at 55⁰C)