A gas system has a pressure, a volume, and a temperature of 1.27atm, 6.17L, and 557.0oC, respectively. How many moles of the gas are present?

Answer 1

Let's start with our Ideal Gas Equation: PV = nRT where P = Pressure (atm), V = Volume (L), n = amount of gas (mol), R = universal gas constant (L*atm/mol*K), and T = Temperature (K). Note the units!

Since we want to solve for moles, let's solve our equation for n. n = PV/RT

Now we can plug in values. P = 1.27 atm, V = 6.17 L, R = 0.0821 L*atm/mol*K, and T = 557.0+273 = 830. K

n = (1.27)(6.17) / (0.0821)(830.) = 0.115 mol of gas

Note 1: The most common mistake students will make when solving gas law problems is forgetting to convert degrees C to K.

Note 2: Your teacher may use a different number of sig figs for the R constant or conversion to K so make sure your work is consistent with your teacher's.