{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Homework 1-solutions

# Homework 1-solutions - phan(dtp377 – Homework 1 –...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: phan (dtp377) – Homework 1 – sutcliffe – (51045) 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points If Δ G ◦ rxn is positive, then the forward reaction is (spontaneous / nonspontaneous) and K is (less / greater) than one. 1. None of these; Δ G is not directly related to K . 2. spontaneous, less 3. spontaneous, greater 4. nonspontaneous; less correct 5. nonspontaneous; greater Explanation: A positive Δ G ◦ rxn (standard reaction free energy) denotes an endothermic reation, which is nonspontaneous. Also, Δ G ◦ rxn =- RT ln K , so a positive Δ G ◦ rxn would result in a K that is between the values of zero and one. 002 10.0 points Which combination of Δ G ◦ and K is im- possible? 1. Δ G ◦ = 79 . 5 J, K = 8 . 46 × 10 13 correct 2. Δ G ◦ = 31 . 8 kJ, K = 2 . 69 × 10 − 6 3. Δ G ◦ =- 92 . 6 J, K = 1 . 04 4. Δ G ◦ =- 101 kJ, K = 4 . 94 × 10 17 5. Δ G ◦ = 71 . 8 J, K = 0 . 971 Explanation: If Δ G ◦ is positive, K must be less than 1; if Δ G ◦ is negative, K must be greater than 1. Also, if Δ G ◦ is small (compared to RT), then K will be close to 1, and if Δ G ◦ is large, K will be much smaller or greater than 1. 003 10.0 points When Δ G is calculated for a proposed reac- tion, the process being described is 1. any mixture of reactants and products converted to equilibrium mixture. 2. 100% reactants converted to equilibrium mixture. 3. 100% reactants converted to 100% prod- ucts. correct 4. any mixture of reactants converted to equilibrium mixture. Explanation: Δ G = Δ G final- Δ G initial = Δ G products- Δ G reactants 004 10.0 points Note: The ’reaction progress’ axis reads from all reactants (far L) to all products (far R) The figure represents a reaction at 298 K. b b b b b G A B C D E rxn progress Based on the figure, the standard reaction is 1. spontaneous. correct 2. nonspontaneous. Explanation: Δ G ◦ is negative (point E is lower free en- ergy than point A), so the standard reaction is spontaneous. 005 10.0 points A gas-phase reaction has K p = 5 . 62 × 10 20 at 25 ◦ C. Calculate Δ G for this reaction. Correct answer:- 118 . 398 kJ / mol rxn. Explanation: phan (dtp377) – Homework 1 – sutcliffe – (51045) 2 K p = 5 . 62 × 10 20 T = 25 ◦ C + 273 = 298 K Δ G =- RT ln K p =- (8 . 314 J / mol · K) (298 K) × ln ( 5 . 62 × 10 20 ) =- 118 . 398 kJ / mol rxn 006 10.0 points Consider the reaction 2 Fe 2 O 3 (s) + 3 C(s) → 4 Fe(s) + 3 CO 2 (g) , Δ H ◦ = 462 kJ , Δ S ◦ = 558 J · K − 1 . Calcu- late the equilibrium constant for this reaction at 525 ◦ C....
View Full Document

{[ snackBarMessage ]}

### Page1 / 6

Homework 1-solutions - phan(dtp377 – Homework 1 –...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online