Che Chm

1. A 385-mL sample of neon exerts a pressure of 670. torr at

26°C. At what temperature in °C would it exert a pressure

of 940. torr in a volume of 560. mL?

(Pi)(Vi)/(Ti) = (Pf)(Vf)/(Tf)

(670 torr)(385 ml)/(299 K) = (940 torr)(560 ml)/(Tf)

Tf= 610 K

2. A 6.0 L sample at 25 °C and 2.00 atm of pressure contains 0.5 moles of a gas. If an additional 0.25 moles of gas at the same pressure and temperature are added, what is the final total volume of the gas?

Vi/ni = Vf/nf

where

Vi = initial volume

ni = initial number of moles

Vf = final volume

nf = final number of moles

For this example, Vi = 6.0 L and ni = 0.5 moles.

When 0.25 moles are added

nf = ni + 0.25 moles

nf = 0.5 moles = 0.25 moles

nf = 0.75 moles

The only variable remaining is the final volume.

Vi/ni = Vf/nf

Solve for Vf

Vf = Vinf/ni

Vf = (6.0 L x 0.75 moles)/0.5 moles

Vf = 4.5 L/0.5 Vf = 9 L

3. 10.0 L of a gas is found to exert 97.0 kPa at 25.0°C. What would be the required temperature (in Celsius) to change the pressure to standard pressure?

Pi/Ti = Pf/Tf

(97.0 Kpa) / (298 K) = (101.325 Kpa) / Tf

Tf = 311 K

Tf = 311K – 273K = 38 degrees Celsius