You are trying to boil water while camping in the colorado rockies. the surrounding barometric pressure is 0.9 bar, and the water is currently boiling. using gibb's phase rule, the system is under specified over specified perfectly specified

Perfectly Specified

Explanation:

Pressure, P = 0.9 atm

Boiling point = T

Number of components C = 1

Number of phases P = 2

Using  Gibbs phase rule as:

F = C - P + 2

F = 1 - 2 + 2 = 1

At Pressure = 0.9 atm, boiling point is T which means that the temperature is also fixed which is equal to 96.7 °C . The data taken from steam table.

In given problem, the pressure is fixed so temperature is also fixed.

The system is perfectly specified.

the maximum mass of nh3 is nh3 in grams