If I have an unknown quantity of gas at a pressure of 5.0 atm, a volume of 17 liters, and a temperature of 45°C, how many moles of gas do I have?

Ok to find the amount of moles of gas you have, you need to use the ideal gas law to solve this problem which is PV=nRT

P is pressure in atm

V is volume in Liters

n is the amount of substance (moles)

R is the ideal gas constant (0.0821)

T is the temperature (make sure its in kelvin) this will be 45+273 = 318K

Now to solve plug the values into the equation

(5) (17) = n (0.0821) (318)

Now solve which will be:

85 = 26.1078n

Then you have to isolate the variable n by dividing both sides by 26.1078 which will get you a final answer of:

3.2557 moles (rounded)