Question

 

1.A sample of nitrogen at 20.0 °C has a volume of 954 mL at a pressure of 1,101 mmHg. To change the volume to 1,496 mL, what must be the new pressure?

2. A sample of nitrogen has a volume of 4.65 L at 1,639 mmHg and 51 °C. What volume will it occupy at standard temperature and pressure?

3. A sample of O₂ gas with a volume of 6.43 L was collected at 278 °C. What is the volume of the gas if the temperature is changed to 99 °C at constant pressure?

Answer 1

(1) We know that PV = nRT

Where

T = Temperature ;P = pressure ; n = No . of moles ;R = gas constant ; V= Volume of the gas

As the gas remains the same , n will constant also the temperature remains the same

So PV = constant

Thereby PV = P'V'

Where

P = initial pressure = 1101 mm Hg

V = initial volume = 954 mL

P'= final pressure = ?

V' = final volume = 1496 mL

Plug the values we get   P' = (PV) / V'

                                       = 702.1 mm Hg

(2) We know that PV = nRT

Where

T = Temperature ;P = pressure ; n = No . of moles ;R = gas constant ; V= Volume of the gas

As the gas remains the same , n will constant

So PV / T = constant

Thereby PV/T = P'V'/T'

Where

P = initial pressure = 1639 mm Hg

V = initial volume = 4.65 L

T = initial temperature = 51^oC = 51+273 = 324K

P'= final pressure = 760 mm Hg

V' = final volume = ?

T' = final temperature = 273 K

Plug the values we get V' = ( PVT') / (P'T)

                                     = 8.45 L

(3) We know that PV = nRT

Where

T = Temperature ;P = pressure ; n = No . of moles ;R = gas constant ; V= Volume of the gas

As the gas remains the same , n will constant also Pressure will remains the same

So V / T = constant

Thereby V/T = V'/T'

Where

V = initial volume = 6.43 L

T = initial temperature = 278^oC = 278+273 = 551K

V' = final volume = ?

T' = final temperature = 99 oC = 99+273 = 372 K

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

                                     = 4.34 L