Ch5 Lec 3

in progress...

Ideal Gas Law Equation (Sec 5.4)

from Crash Course

When combining all of the gas laws, Boyles, Charles', and Avogadro's we get the Ideal Gas Law Equation: As with any mathematical relationship/equation, if there are 5 variables (P, V, n, R, T) all you need to know is 4 of them and the 5th can be calculated.

R, the gas constant is equal to (depending on the units):

Question 1

If given the following data, which gas constant would you use?

P = 1.12 atm

V= 2.45 L

n = 1.00 moles

T = 298 K

Answer: 0.082057 L*atm/(mol*K)

If the volume was not given in the question above, show how it can be calculated:

P = 1.12 atm

n = 1.00 moles

T = 298 K

R = 0.082057 l*atm/(mol*K)

Calculate V and make sure your work shows how the units cancel:

Question 2

If given the V, n, and T, which gas constant would you use if you want to calculate the pressure in "bar"?

Answer: 0.08314 L*bar/(mol*K)

Given:

V= 22.414 L

n = 1.0000 moles

T = 273.15 K

R = from above...

Calculate the pressure in bar and make sure your work shows how the units cancel:

Comments on Temperature: Always use Kelvin. ^oC + 273.15 = K

Nearly all gases behave similarly when under a set of conditions (P, V, and T). So much so that we define a set of conditions, "standard temperature and pressure" (STP) as T = 273.15 K and P = 1 atm. Under STP, the volume of 1.00 moles of gas is 22.4 L. This concept was discussed in the crash course video.

from Crash Course

As you might expect...there is a short WA waiting for you...(8 am, Weds)...

End of Chapter 5