Question

The volume of a sample of gas is 4.50 L at STP What volume will the sample occupy at 20.0`"^o`C and 650.0 torr?

Answer 1

5.65 L

Explanation:

First, recall that “Standard” temperature and pressure are 0’C and 1 atm (760Torr), as opposed to “Normal” temperature and pressure of 20’C and 1 atm.

In the Ideal Gas Law calculations all temperatures must be in “absolute” (‘Kelvin) degrees for the ratios to work correctly. Either Torr (mm Hg) or atm may be used for the pressure values.

From the Ideal Gas Laws we know that `((PV)/T)_1 = ((PV)/T)_2`

Inserting our given values into this equation with the correct temperature values we get:

`(760 * 4.50L)/(273’K) = (650.0 * V_2)/(293’K)`

`V_2 = (760/650) * (4.50)*(293/273)`

`V_2 = 5.65 L`