Initial Pressure air = 101.99 kPa Initial Temperature air = 21.3 Celsius Pressur
ID: 884368 • Letter: I
Question
Initial Pressureair = 101.99 kPa Initial Temperatureair = 21.3 Celsius
Pressure (kPA)
Temperature (Celsius)
trial 1
105.80 kPA
21.4 C
trial 2
108.69 kPA
25.5 C
trial 3
111.42 kPA
29.0 C
trial 4
115.18 kPA
33.1 C
trial 5
117.07 kPA
36.6 C
1. For each temperature point, Calculate the pressure of just the air in the flask. Show one calculation, then list the other results.
2. Using the Pair calculated in the previous question and the Ptotal measured in the experiment calculate the Pvap, ethanol at each temperature. Show one calculation.
Pressure (kPA)
Temperature (Celsius)
trial 1
105.80 kPA
21.4 C
trial 2
108.69 kPA
25.5 C
trial 3
111.42 kPA
29.0 C
trial 4
115.18 kPA
33.1 C
trial 5
117.07 kPA
36.6 C
Explanation / Answer
We can use the Ideal GAs Law to get the result.
The Ideal Gas Law is given by,
PV/T = constant.
Where P is the Pressure, V is the volume and T is the temperature in Kelvins(be careful, the temperature has to be in Kelvin else you will get incorrect results).
1) We will use the first trial.
so PV/T= constant (since the volume is alsso constant), the equation reduces to P/T=constant.
so, Pi/Ti = Pf/Tf
101.99/(273+21.3) = P/(273+21.4)
or P1=102.024 kPa
similarly, for the other trials,
P2=103.4455 kPa
P3=104.6584 kPa
P4=106.0793 kPa
P5=107.2922 kPa
2)Pvap,ethanol + Pair = Ptotal
so, for the first trial,
Pvap,ethanol = 105.8-102.024
= 3.776 kPa
for the second trial,
Pvap,ethanol = 108.69 -103.4455
=5.2445 kPa
for the third trial,
Pvap,ethanol = 111.42-104.6584
Pvap,ethanol = 6.7616 kPa
for the fourth trial = 115.18 - 106.0793
for the fifth trial,
Pvap,ethanol = 117.07 - 107.2922
=9.7778 kPa