Engineering Chemistry Questions and Answers – Gibb’s Phase Rule

This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Gibb’s Phase Rule”.

1. What does Gibb’s phase rule state?
a) P+F=C-1
b) P+F=C+1
c) P+F=C-2
d) P+F=C+2
View Answer

Answer: d
Explanation: The above phase rule is a formula that gives the condition for finding the number of phases in a system. This phase rule can be applied to both condensed as well as normal systems.

2. What is the point at which all the three phases of a system exist?
a) Triple point
b) Sublimation point
c) Vapor point
d) Eutectic point
View Answer

Answer: a
Explanation: Since at the triple point, the degree of freedom is zero (that is invariant reaction takes place at that point), therefore according to phase rule, F=C-P+2. Substituting the known values, we get P=3 (all states).

3. For water system, the number of phases at the triple point is _____________
a) 0
b) 1
c) 2
d) 3
View Answer

Answer: d
Explanation: Since at the triple point, the degree of freedom is zero, while applying the formula F=C-P+2, we get the number of phases as three because C=1, F=0 (since water system forms only single component).
advertisement
advertisement

4. Liquid phase exists for all compositions above _________ region.
a) Eutectic region
b) Equilibrium region
c) Isometric region
d) Sublimation region
View Answer

Answer: c
Explanation: In a phase region above the eutectic point, both the solid and liquid phases exist together where the region is bi variant and this region is called isometric region. Here the region has 2 degrees of freedom.

5. Select the wrong statements from the following statements with respect to a phase diagram.
a) Gives information about concentration
b) Gives information about solubility
c) Gives information on melting and boiling points
d) Gives information on relative concentration
View Answer

Answer: d
Explanation: A phase diagram gives information only on the concentration of species, their solubility rate, degree of freedom and other physical properties. It does not explain about transformation rates and relative concentration (relative concentration=total concentration/equilibrium concentration).
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. Select a non-homogeneous system from the following.
a) Salt solution
b) Sugar solution
c) Glucose in water
d) Saturated solution of NaCl
View Answer

Answer: d
Explanation: A homogeneous mixture is one which is miscible completely with one another. In any saturated solution, when the amount of solute reaches more than a critical point, then the solution becomes heterogeneous.

7. Select the odd statement with respect to a phase reaction.
a) Saturated solution
b) Equilibrium solution
c) Concentric solution
d) Amorphous solution
View Answer

Answer: a
Explanation: A terminal solution, an intermediate solution, an equilibrium solution and concentric solutions, are the ones which take part in a phase reaction. On the other hand, a saturated solution is involved in the Lever system.
advertisement

8. Which of the following is the formula for condense phase rule?
a) F=C-P+2
b) F=C-P+1
c) F=C+P-2
d) F=C+P-1
View Answer

Answer: b
Explanation: In a condensed phase rule system, the phases are represented in three dimension which is not suitable for graphic purposes and hence the pressure is considered to be zero (this is helpful in drawing 2D images). Hence the formula reduces to F=C-P+2.

9. Calculate the eutectic concentration given the following data.
Pressure= 1atm
Temperature: 1oC
a) 0
b) 2
c) 1
d) 3
View Answer

Answer: c
Explanation: According to Weiss law (which suits only for phase components), concentration at equilibrium is C=T/P. therefore in this case, C=1/1=1. This law is also called as Gibbs relativity law.
advertisement

10. Under what condition, will we get a stable phase diagram?
a) Solid + Liquid
b) Solid + Vapor
c) Liquid + vapor
d) Liquid + Solid
View Answer

Answer: a
Explanation: According to equilibrium mixture ration, an appropriate ratio of 1:10 parts of solid and liquid along with an aqueous solution will give a stable phase product.

Sanfoundry Global Education & Learning Series – Engineering Chemistry.

To practice all areas of Engineering Chemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.

advertisement
advertisement
Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & discussions at Telegram SanfoundryClasses.