5. (a) Based on the reactions listed below, determine delta H for the reaction (

Question

5. (a) Based on the reactions listed below, determine delta H for the reaction (b) Rank the following gas molecules in order of increasing entropy: C3H8, CH4, C6H14. What is the cause of increasing entropy for whatever order you decided on? (c) If you created a galvanic cell by placing copper metal in a 70 mL solution composed of 0.1 moles of dissolved Cu2O in dilute acid on one side and silver metal in a 60mL solution composed of 0.1 moles of AgCl dissolved in dilute acid what would be the voltage at 25 degree C given Cu+ + e- Cu 0.52V and Ag+ + e- Ag 0.8V

Explanation / Answer

a)
Let us name all 5 reactions as 1,2,3,4 and 5
If we see carefully, we can find that, reaction 1 can be writtten as :
- 0.5*reaction 2 -0.5 reaction 3 +0.5 reaction 3-0.5 reaction 4

so, delta H = -0.5*507 - 0.5*(-427) + 0.5*(-43) -0.5 (34)
    = -78.5 KJ
b)
Greater mass lesser entropy
C6H14<C3H8<CH4
c)
[Cu+] = 0.1 mol/0.07 L = 1.43 M
[Ag+] = 0.1mol/0.06 L = 1.67 M
Net cell reaction will be:
Ag+ + Cu ---> Cu+ + Ag
Eo cell = 0.8 - 0.52 = 0.28 V

use:
E = Eo - 0.059 * log {[Cu+]/[Ag+]}
    = 0.28 - 0.059 * log (1.43/1.67)
    = 0.276 V
Answer: 0.276 V

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