Predict the effect of an increase in pressure and temperature on the production of ammonia in the reaction: N2(g) + 3H2(g) <-> 2NH3 (g) , where the change in enthalpy is -92.4 kJ

An increase in temperature and an increase in pressure will have contradictory effects on the reaction.

The effect of an increase in the temperature of a system, on the equilibrium of a reaction, is dependent on whether the reaction is endothermic (positive change in enthalpy) or exothermic (negative change in enthalpy).

The forward reaction is exothermic since the change in enthalpy is negative. If we increase the temperature of the system the extra heat energy is converted into chemical energy. Thus, the position of equilibrium moves towards the endothermic reaction. In the case of our reaction an increase in temperature would shift the position of equilibrium towards the endothermic backwards reaction, reducing the yield of ammonia produced.

A change in pressure will only have an effect on equilibria involving gaseous molecules. An increase in pressure results in more molecules per area within the system. The effect of this upon the position of equilibrium is dependent on the gas molecules on either side of equilibrium. The system reacts to an increase in pressure by favouring a reduction in pressure. Since we have four gas molecules on the left and two on the right of our reaction, an increase in pressure will shift the position of equilibrium to the right, favouring the forward reaction and increasing the overall yield of ammonia produced.

Aaron S. A Level Biology tutor, GCSE Biology tutor, A Level Chemistry...

2 months ago

Answered by Aaron, an A Level Chemistry tutor with MyTutor

Still stuck? Get one-to-one help from a personally interviewed subject specialist


PremiumMichal D. A Level Chemistry tutor, IB Chemistry tutor, Mentoring Chem...
View profile
£26 /hr

Michal D.

Degree: Chemistry (Masters) - Oxford, Jesus College University

Subjects offered: Chemistry


“A 2nd year Chemistry student at University of Oxford looking to help you with any problems with the subject. Chemistry may seem difficult to you. This is probably because you don't know WHY something works the way it works. You don't ...”

PremiumHannah G. A Level Chemistry tutor, A Level Biology tutor, GCSE Chemis...
View profile
£26 /hr

Hannah G.

Degree: Chemistry (Other) - Liverpool University

Subjects offered: Chemistry, Science+ 1 more


“First year Chemistry undergraduate, looking to help you achieve your full potential in Chemistry and Biology. ”

Fahad M. A Level Maths tutor, A Level Chemistry tutor, A Level Biolog...
View profile
£30 /hr

Fahad M.

Degree: Medicine And Surgery - MBChB (Bachelors) - Birmingham University

Subjects offered: Chemistry, Psychology+ 7 more

.BMAT (BioMedical Admissions)
-Personal Statements-
-Medical School Preparation-

“About MeGraduating highschool with many distinctions I went on to become a medical student at the University of Birmingham. Having excelled in my interview (gaining the top rank in Motivation and Experience) I went on immediately to ...”

About the author

Aaron S. A Level Biology tutor, GCSE Biology tutor, A Level Chemistry...
View profile
£20 /hr

Aaron S.

Degree: Experimental Pharmacology and Therapeutics (Masters) - University College London University

Subjects offered: Chemistry, Biology+ 1 more

-Personal Statements-

“My Name is Aaron, I recently graduated with first class honours degree in Biochemistry and am currently undertaking a MSc degree in Experimental pharmacology and therapeutics. I have gained experience tutoring from mentoring undergrad...”

MyTutor guarantee

You may also like...

Other A Level Chemistry questions

What are optical isomers?

What evidence is there to support the delocalised model of benzene over Kekulé's model?

What is le Chatelier's principle?

View A Level Chemistry tutors


We use cookies to improve our service. By continuing to use this website, we'll assume that you're OK with this. Dismiss