Question

What initial volume (in mL) will 0.00660 mol of hydrogen gas occupy at a pressure of 0.907 atm and a temperature of 9°C? If you heat the sample up to 45°C and maintains a constant pressure, what is the final volume (in mL)?

Answer 1

Ideal gas equation is PV = nRT

Where P = pressure = 0.907 atm

V = volume = ?

n = number of moles = 0.00660 mol

R = gas constant = 0.0821 L atm / mol-K

T = temperature = 9 ^oC = 9+273 = 282 K

Plug the values we get   V = nRT / P

                                           = ( 0.00660 x 0.0821 x 282 ) / 0.907

                                           = 0.153 L

So the volume occupied by H₂ gas is 0.153 L

Since pressure & the number of moles of the gas remains constant , So V T

So V / V' = T / T'

Where

V = initial volume = 0.153 L

V' = final voluime = ?

T = initial temperature = 9 ^oC = 9 + 273 = 282 K

T' = final temperature = 45 oC = 45+273 = 318 K

Plug the values we get V' = VT' / T

                                          = ( 0.153 x 318 ) / 282

                                          = 0.172 L

Therefore the final volume of the gas is 0.172 L