Question

Calculate the final pressure, in millimeters of mercury, for each of the following, if volume and amount of gas do not change: Part A A gas with an initial pressure of 1400 torr at 158 °C is cooled to 0°C Express your answer to two significant figures and include the appropriate units. P= Value Units Submit Request Answer Part B A gas in an aerosol can at an initial pressure of 1.40 atm at 15°C is heated to 38°C. Express the pressure to three significant figures and include the appropriate units. P= Value Units Submit Request Answer

Answer 1

Assuming ideal behaviour we know that for a gas if pressure is P, temperature (in K) is T ;then P is directly proportional to T

a) T1=1580C = 431K, T2= 00C = 273K

so P​​​​​1​​​​​/P​​​​​​2=T​​​​​1/T 2

Here P​​​​​​1= 1400 torr = 1400 mm Hg

Hence P2 = 1400*273/431 = 8.9* 102 mm Hg= 1.2 atm

b) here P1= 1.4 atm = 1.4 * 760 mm Hg = 1064 mm Hg, T1= 150C = 288 K, T2= 311 K

So P2 =1064*311/288 = 1.15*103 mm Hg = 1.51 atm

As here mentioned about significant figure so pressure in atm unit will be more acceptable as it will match with significant no requirements.

1 torr =1 mm Hg= (1/760) atm this is the governing relation of pressure term.