Chemistry questions

Question

You are given a sample of chlorine gas with a volume of 9.00 liters, a temperature of 15 degrees Celsius, under pressure of 80.0 kilopascals. How many miles of chlorine gas do you have?

Answer 1

What you know (are given):

V1 (initial volume) = 9.00 L

T1 (initial temperature) = 15ºC + 273 = 288K

P1 (initial pressure) = 80.0 kPa

Question (need to find):

number of moles of gas (n)

Using the Ideal Gas Law, we know that PV = nRT, and solving for n (moles), we have...

n = PV/RT. Now we plug in our values, being sure to use the correct value for the gas constant (R), since the value of R varies with the units of pressure. For a pressure in kPa, we use R = 8.314 L-KPa/K-mole.

n = (80.0 kPa)(9.00 L)/(8.314 L-atm/Kmol)(288K)

n = 0.301 moles of Cl₂ gas (to 3 significant figures)

If you want to change kPa to atmospheres, and use the more conventional value of R = 0.0821 L-atm/K-mole,

then 80.0 kPa x 1 atm/101.325 kPa = 0.7895 atm

n = (0.7895 atm)(9.00 L)/(0.0821 Latm/Kmol)(288)

n = 0.301 moles Cl₂ gas

Answer 2

You can use the ideal gas equation here: PV = nRT. Rearrange to n = PV/RT.

n = (80.0 kPa)(9.00 L)/(8.314 L•kPa/K•mol)(15 + 273.15 K) = 0.301 mol