Question #99359

To find the gas constant, assume you are at Standard Temperature and Pressure conditions (STP) and you have one mole of gas.
Then, P= 1 atmosphere, T= 273 K, V= 22.4liters and n= 1 mole.
When you plug these values into the ideal gas law formula:
PV=nRT, you find that R, the constant, is equal to 0.0821. This is the constant as long as you remember to change your pressure to atmospheres (mm Hg/760 = atm), your volume to liters (ml/1000 = liters), and of course your temperature must always be in Kelvin (C + 273).

For your problem:
(1.95 atm) (12.30) = (.654 moles) (0.0821) (K)
K=447

The value of the gas constant #R# is a number that your teacher should give you in a test situation or that you can look up if you are doing a homework assignment.

In this problem, you have to find #T#, so you look up the value of #R# (#"0.082 06 L·atm·K"^"-1""mol"^"-1"#).

Since #PV = nRT#,

#T = (PV)/(nR) = (1.95 color(red)(cancel(color(black)("atm"))) × 12.30 color(red)(cancel(color(black)("L"))))/(0.654 color(red)(cancel(color(black)("mol"))) × "0.082 06" color(red)(cancel(color(black)("L·atm·")))"K"^"-1"color(red)(cancel(color(black)("mol"^"-1")))) = "447 K" = "174 °C"#

The temperature of the gas is 174 °C.