Question

A 1.15 mol sample of carbon monoxide gas has a temperature of 27°C and a pressure of 0.300 atm. If the temperature were lowered to 17°C, at constant volume, what would be the new pressure?

Answer 1

The new pressure will be 0.29 atm .

Explanation:

This is an example of Gay-Lussac's gas law, which states that the pressure of a given amount of gas kept at constant volume is directly proportional to the temperature in Kelvins.

The equation for this gas law is `(P_1)/(T_1)=(P_2)/(T_2)`. Notice that the number of moles is not a variable in the equation. The number of moles was given to indicate that the `"1.15 mol CO"_2"` does not change, and is the "given amount of gas."

Determine the known and unknown values.

Known
`P_1="0.300 atm"`
`T_1="27"^@"C"+"273.15"="300 K"`
`T_2="17"^@"C"+"273.15"="290 K"`

Unknown
`P_2`

Solution
Rearrange the equation to isolate `P_2`. Substitute the known values into the equation and solve.

`P_2=(P_1T_2)/(T_1)`

`P_2=((0.300"atm")xx(290cancel"K"))/(300cancel"K")="0.29 atm"`