Question

The substance nitrogen has the following properties:

normal melting point:	63.2 K
normal boiling point:	77.4 K
triple point:	0.127 atm, 63.1 K
critical point:	33.5 atm, 126.0 K

A sample of nitrogen is initially at a pressure of 40.9 atm and a temperature of 56.8 K. The pressure on the sample is reduced to 0.127 atm at a constant temperature of 56.8 K. Which of the following are true?

Choose all that apply

The sample is initially a solid.

The final state of the substance is a gas.

The gas initially present will solidify.

The final state of the substance is a solid.

No phase change will occur.

Answer 1

Using the data the phase diagram is

From the given data at 40.9 atm and 56.8 K the gas is solid.

Now as triple point is 0.127 atm , 63.1 K.

So, at 0.127 atm and 56.8 K the nitrogen is present in solid state.

So, correct options are

The sample is initially a solid.

The final state of the substance is a solid.

No phase change will occur.