How much heat must be rmoved from 20C nitrogen gas to produce 1L of liquid nitrogen? density of N=810kg/m^3?

Answer 1

The total heat energy required is:
1) the heat energy required to cool the 0,81kg of N2 to its liquifaction temperature:
Q = m * s * TempChange:

2) the heat energy required to Liquify the N2:
Q = m * L

3) the heat energy required to cool the 0,81kg of liquid N2 to its final temperature:
Q = m * s * TempChange:

now just add up the three values to give your final extracted heat enegy value.
You will need to look up the specific heat capacity of both liquid and gaseous N2 and also its latent heat of vaprorisation.
I hope this enables you to work your way through this Question!