Calculate the entropy change for the reaction: N2(g) + 3H2(g) -> 2NH3(g) Entropy data: NH3 = 192.5 J/mol K H2 = 130.6 J/mol K N2 = 191.5 J/mol K

Expert Answers

An illustration of the letter 'A' in a speech bubbles

The entropy change for the given reaction, involving the manufacturing of ammonia from nitrogen and hydrogen, can be calculated as the difference between the entropy of the products and reactants. In other words:

The entropy change of the reaction = entropy of products - entropy of the reactants

For the given chemical reaction:

N2 + 3H2 -> 2NH3

Entropy of products = 2 x entropy of ammonia = 2 moles x 192.5 J/mol K = 385 J/K

Similarly, entropy of reactants = 1 mole x entropy of nitrogen + 3 moles x entropy of hydrogen

= 1 mole x 191.5 J/mol K + 3 moles x 130.6 J/mol K

= 583.3 J/K

Thus, the entropy change for the manufacturing of ammonia can be calculated as:

Entropy change = entropy of products - entropy of reactants

= 385 J/K - 583.3 J/K = -198.3 J/K

Hope this helps.

Approved by eNotes Editorial Team

We’ll help your grades soar

Start your 48-hour free trial and unlock all the summaries, Q&A, and analyses you need to get better grades now.

  • 30,000+ book summaries
  • 20% study tools discount
  • Ad-free content
  • PDF downloads
  • 300,000+ answers
  • 5-star customer support
Start your 48-Hour Free Trial