When boiling water, what is the degree of freedom inside the vapour dome?

[Death eater]

When water converts to steam while boiling a vapour dome can be formed, what is the degree of freedom inside this vapour dome and on the saturated points?

 

[Bystander]

Are you asking about, or how to apply, the phase rule?

 

[Death eater]

Are you asking about, or how to apply, the phase rule?

Actually I wanted to understand why degree of freedom is 1 in the wet region ??
I know by the Gibbs formula it comes 1 but to locate certain point inside the dome we need to know two properties ( eg- pressure and dryness fraction) ?
How can we define the state by just one intensive property?

 

[Bystander]

dryness fraction

How many components?

 

[Death eater]

How many components?

There is only 1 component

 

[Bystander]

only 1 component

At equilibrium?