Question #c1c9e

1 Answer
May 30, 2014

The approximate temperature is 20 °C.

To solve this problem, we can use the Ideal Gas Law

PV = nRTPV=nRT.

In the formula, PP is the pressure, VV is the volume, nn is the number of moles of gas, RR is the Universal Gas Constant, and TT is the Kelvin temperature.

We want to solve the Ideal Gas Law for TT.

To get TT by itself, we must divide both sides of the equation by nRnR:

PV = nRTPV=nRT

(PV)/(nR)PVnR = (nRT)/(nR)nRTnR

(PV)/(nR) = TPVnR=T.

Thus,

T = (PV)/(nR)T=PVnR

Substituting values, we get

T = (PV)/(nR) = (0.987"atm" × 12"L")/(0.50"mol" × 0.082 06"L·atm·K⁻¹mol⁻¹") = 290 K

Notice how the units cancel to give the temperature in kelvins.

Now we convert to the Celsius temperature:

290 K = (290 - 273.15)°C ≈ 20 °C

Note: I have calculated the answer to only 1 significant figure, because the number of moles and the volume had only 2 significant figures.

The calculated Kelvin temperature had only 2 significant figures. When we subtracted 273.15, we lost one of these significant figures. If you need more precision, you will have to recalculate.