Question

Test IV (Electrochemistry) 2018 Fall What is the oxidation number for the Which of the following is true concerning a galvanic cell? (A) Oxidation occurs at the anode and is 1. 8. underlined manganese in Mn04 (A)-8 (8)-2 (C)-1 (D)4 (E) 7 where anions move towards where anions move towards where cations move towards where anions move towards where anions move towards 2. When balancing the below half-reaction in acidic solutionelectrons are added to the (B) Oxidation occurs at the cathode and is (C) Oxidation occurs at the anode and is (D) Reduction occurs at the cathode and is (E) Reduction occurs at the anode and is side of the equat (A) 6, reactant (C) 8, reactant (B) 6, product (0) 8, product 3. The oxidizing agent in the below reaction is Fe(s)+Cu'(ag) Fe (ag) + Cu(s) (A) Fe(s) (C) Fe (oq) (D) Ethanol, C HoO, is used in a fuel cell, for which the overall reaction is the combustion of ethanol. The anode half-reaction is: ChLO(g) + 3H20() .-2CO,(g) + 12H.(aq) + 12e" What is the cathode half-cell reaction? 9. (B) Cu (aq) 4. What is the total number (n) of electrons transferred in the below reaction? 2S203 (aq)+2Cu(ag) (B) 2H(aq)+ 2e (C) 2H20(/) + 2e-→ H2(g) + 2OH-(aq) (D) O(g) 2H20()+4e40H (aq) (E) 02(g)+ 4H*(aq)+4e 2H2OU H2lg) S,0% (ag) +2Cu'(ag) (A) 2 (8)3 (C)4 (D) 6 (E) 8 5. If Eu 1.50 V, ECa*/ca -2.87v what is Eoetl for the below reaction? 10. What is the equilibrium constant for the below reaction at 25 C? 2Au(s) + 3Ca2"(aq)-→ 2Au1+(aq) + 3Ca(s) (A) 4.37 V (B) 1.37 V (C)-1.37 V (D)-4.37V(E)-11.6V 2H20 (aq) 2H200) +0:(g) Standard Reduction Potentials, V H,02(aq) + 2H+(aq) + 2e 120(1) +1.77 If a galvanic cell is made of a standard hydrogen electrode (SHE) and a silver 0g)+2H(a)e (A) 7.5x103 (C) 2.7x1018 HOaq)+0.68 (B) 1.3x10- (D) 3.6x10-19 6. electrode, what is the overall cell reaction? (A) 2H (aq) + 2Ag (aq) > H2(g)+2Agls) (B) H'(ag) + Ag(s) H2(g)+ Ag (aq) (C) 2H'(aq)+ 2Ag(s) > H2(g)+2Ag (ag) (D) H2(g) + Ag(aq) H'(aq)+2Agls) (E) H2(g) 2Ag(aq) 2H (aq)+ 2Ag(s) 11. Which statement is true for a galvanic cell? 12. Which statement is true for an oxidation- 7. When a voltaic cell reaches equilibrium, which following will be zero? (A) E (D) Kc reduction reaction if the equilibrium constant K is less than 1? (A) It is spontaneous (B) E is positive (C) AG® is negative (D) It is nonspontane (E) More than one of above (C) ΔΗ' (E) AS Page

Answer 1

Ans 1 : E) 7

The charge of the ion is -1

The default oxidation state of O is -2

Let the oxidation state of Mn be x

So putting values :

x + 4(-2) = -1

x = +7

So the oxidation state of Mn will be +7.