The pressure of a gas changes from 120kPa to 50kPa. The volume changes from 45L to 40L. If the initial temperature is 81°C, what is the final temperature in Kelvin units?

The final temperature is 131 K

Explanation:

Step 1: Data given

The initial pressure = 120 kPa = 1.18431 atm

The final pressure = 50 kPa = 0.493462 atm

The initial volume = 45 L

The final volume = 40 L

The initial temperature = 81 °C = 354 K

Step 2: Calculate the final temperature

(P1*V1)/T1 = (P2*V2)/T2

⇒with P1 = the initial pressure = 1.18431 atm

⇒with V1 = the initial volume = 45 L

⇒with T1 = the initial temperature = 354 K

⇒with P2 = the final pressure = 0.493462 atm

⇒with V2 = the final volume = 40 L

⇒with T2 = the final temperature = ?

(1.18431 * 45)/354 = (0.493462*40)/T2

0.15054788 = 19.73848/T2

T2 = 19.73848/0.15054788

T2 = 131 K

The final temperature is 131 K

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"