Question 2 (20 points)\ Determine the degrees of freedom for the following systems:\

F=N-\\\\pi +2

\ (a) Pure water at the triple point.

F=1-3+2=0

\ (b) A liquid/vapor mixture of ethanol, methanol, and water at

100kPa

and

60\\\\deg C.F=3

2+2=3

. However,

T

and

P

are fixed so

F=3-2=1

\ (c) A liquid/vapor mixture of benzene and water at

100kPa

. Since benzene is not soluble in water, then we have 2 liquid phases.

F=2-3+2=1

and since

P

is constant,

F=0

\ (d) A gaseous mixture of nitrogen and oxygen at

25\\\\deg C.F=2-1+2=3

and since

T

is constant

F=3-1=2

. In addition,

PVT

are related then

F=2-1=1

. This means that once

P

or

V

is known, the other property can be determined.