20. What is the change in entropy at 298 K of the surroundings if a reaction is
ID: 637091 • Letter: 2
Question
20. What is the change in entropy at 298 K of the surroundings if a reaction is 150 kJ exothermie? a)+839 J/K b)+4.47 X 107 J/K c) +1.98 J/K d)+503 J/K e)+1,170 J/K 21. How many electrons are transferred in the following balaneed redox reaction ( 4 Al(s) + 3 Odg) ? 2A|201s) )? a)3 b) 6 c)9 d)12 e) 8 22. Under acidic conditions, when the half reaction (H NO2(aq) ? NO(g) ) ?s balanced, electrons are added to the side of the half reaction. ?) 2, left nonspontaneous (AH' = +198.2 kJ: AS. +189.6 J/K )? a) 517 K b) l, right c) 2, right d) 3, right e) 1, left 23. At what temperature does the reaction (2 SOs(g) 2 S0-(g)+ 0:(8)) switch from being spontaneous to b) 1,045 K c) 787 K d)298 K e) it is nonspontaneous at all temperatures 24. A reaction has a decrease in entropy of the system and is spontaneous. Therefore: a) the reaction is exothermic b) AGy, is positive c) AS yd) the surroundings have a decrease in entropy e) the universe has a decrease in entropy 25. Which of the following act as driving force(s) for a chemical reaction? a)reaction is exothermic b)reaction is endothermic c) reaction has an increase in entropy of the system d) reaction has an decrease in entropy of the system e) both a and eExplanation / Answer
20. Correct option is B
21.Correct otion is C as
The two half reactions are:
half oxidation: Al --> Al+3 + 3e-
half reduction: O + 2e- --> O2-
In the Second 1/2reaction, 3 electrons are transferred.
4 Aluminum ions are used in the equation, so 12e (4x3) are transferred in total.
Then in the second 1/2reaction
6 Oxygen ions used gaining 2e each = 12 (6x2) electrons transferred in total.
22. Answer B is correct
You have to move from 3 to 2
hence add 1 electron in the right side
23. answer is E the reaction is spontaneous at all temperature
24. answer A is correct the reaction will be exothermic
25. Answer E is correct as in both cases there it will provide a driving force to move in forward direction
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