Given: P1: 4.2162 atm, P2: 5.7166 atm, V2: 53.914L, T1: 681.53K, T2: 891.28K , Wanted: liters of CH4

Answer 1

Hello, Brandy,

We can use a gas law relationship in a case where there is no gain or loss of the number of moles of the gas. It is:

P1V1/T1 = P2V2/T2

Where P, V, and T are pressure, volume and temperature (in Kelvin), respectively. The subscripts 1 and 2 mean initial and final.

Make a table with the values and rearrange the equation to solve for the unknown, In this case, the unknown is V1.

V1 = V2(P2/P1)(T1/T2)

I’ve arranged the equation to demonstrate that the initial volume is a function of the final volume times the ratio of initial and final temperatures and pressures. (T1/T2) tells us the impact due to the temperature change, and. (P2/P1) the impact of the pressure change.

Set up a table and enter the data. Pay attention to see if the units cancel to leave liters. Also be certain that temperatures are in Kelvin, which they are already, in this case.

Before we do the calculation, make a prediction as to what should happen. (T1/T2) is less than 1 so this will reduce V1 by around 25%, I would judge. (P2/P1) is higher, by about 35%. These tend to cancel each other out, but it seems that we might expect a 10% increase for V1, around 59L, using very approximate mental calculations.

Plug in the numbers from the table

V1 = V2(P2/P1)(T1/T2)

I get V1 = 55.9 L

We guesstimated 59L, but I'm comfortable with this result. It went in the correct direction, by around %

..

Bob