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How many mol of CH4 are in a 150 L
tank exerting a pressure of 20.0 atm when the temperature
is 24.0 degrees Celsius?
Problem Solving Strategy:
Since this is a problem about a gas, and all the data
provided are physical properties we conclude it is an Ideal Gas Law Problem
and we need to construct a table to associate values in the problem statement
with the variables in the Ideal Gas Law (PV = nRT).
Completing the table with the data from the problem;
P
|
V
|
n
|
R
|
T
|
Condition
|
20.0 atm
|
150 L
|
?
|
0.0821 L atm mol-1 K-1
|
24.0 C
|
1
|
Notice there is only one condition for this gas. If
there were more than one condition we would extend the table for additional
conditions. Before continuing we must convert all the units for each variable
so they correspond to the units for R. In this problem the units on pressure
and volume agree with the units in R, but the units on temperature are in Celsius.
Temperature units must be Kelvins in any Ideal Gas Law Problem
Converting degrees Celsius to Kelvins;
K = 273.15 + degrees Celsius
K = 273 + 24.0 = 297
K
Click here to show the table with
the correct values for each variable.