16A.3

Question 1

in an electrochemical cell how does electrons flow

Answer 1

from the half cell with the more negative E, to the have cell with the more positive E

Question 2

electrode potential can tell us

Answer 2

how easily a species loses electrons

Question 3

what is a thermodynamically feasible reaction

Answer 3

a reaction that should take place without any intervention from us, if we consider the enthalpy and entropy changes involved

Question 4

how is a reaction in electrochemical cell thermodynamically feasible

Answer 4

if there is a large gap between the standard electrode potential values with the element giving the electron having a more negative number

Question 5

is the reaction between cupper (s) and dilute sulfuric acid and its reverse reaction thermodynamically feasible

Answer 5

no since cupper E is more positive so it wont give electrons to H, but the reverse reaction works but H gas is never bubbled into a cupper ion solution since too high Ea so the reactants are kinetically stable

Question 6

what is a kinetically stable

Answer 6

the reaction does not take place, or is very slow, because the Ea of the reaction is very high

Question 7

is the reaction between cupper and zinc thermodynamically feasible

Answer 7

yes since zinc has a more negative E

Question 8

is the reaction between zinc and dilute sulfuric acid thermodynamically feasible

Answer 8

yes since zinc has a more negative E

Question 9

What is the reaction between Manganese (IV) oxide and hydrochloric acid

Answer 9

MnO2 (s) + 4HCl(aq) ——> Mn^2+(aq) + 2Cl^-(aq) + 2H2O(l) + Cl2(g) (this is wrong lol)

Question 10

is the reaction between Manganese (IV) oxide and hydrochloric acid thermodynamically feasible

Answer 10

no since Cl needs to release electrons but Mn is has a more negative E

Question 11

What are the two have equations involved in Manganese (IV) oxide and hydrochloric acid

Answer 11

MnO2(s) +4H^+(aq) +2e- ——> Mn^2+(aq) + 2H2O(aq)

Cl2(g) + 2e- —-> 2Cl^-(aq)

Question 12

how do we make the reaction between Manganese (IV) oxide and hydrochloric acid thermodynamically feasible

Answer 12

By increasing the concentration of hydrochloric acid to 10 mol dm^-3, that means that with more hydrogen ions the eq at MnO2 half cell will shift to the right and with more Cl ions the eq at Cl2 will shift to the left, so the E of MnO2 because more positive than the E of Cl2 allowing Cl to lose electrons and give to MnO2

Question 13

the thermodynamic feasibility of a chemical reaction can be predicted using

Answer 13

standard electrode potential

Question 14

the E values may indicate that a reaction is thermodynamically feasible yet it may not take place, what are the two reasons

Answer 14

1. the reaction is kinetically stable because the Ea for the reaction is too large
2. the reactions might not take place under standard conditions

Question 15

a reaction might not be thermodynamically feasible under standard conditions but

Answer 15

may become feasible when the conditions are altered

Question 16

changing the conditions may alter the

Answer 16

standard electrode potential of a half cell since the positions of the eq of the half cell might change

Question 17

what does disproportionation reaction mean

Answer 17

a reaction at which the element is both oxidized and reduced at the same time

Question 18

what is the most common disproportionation reaction

Answer 18

the conversion of copper ions into copper 2+ ions and copper atoms ( reactions page 170

Question 18

explain how the the conversion of copper ions into copper 2+ ions and copper atoms reaction is feasible

Answer 18

because on Cu+ comes from Cu^2+ + e- —-> Cu^+ and the other comes from Cu^+ + e- —–> Cu with the first eq have a more negative E so it gives electrons to the Cu in the second eq

Question 19

what is the equation that defines Ecell and entropy

Answer 19

T x Entropy = nFEcell with F = faradays law

Question 20

number of moles is constant in a cell reaction, and F is also constant, so it follows that at a given temperature the rs between Entropy and E is

Answer 20

E cell (directly proportional) to Entropy ( in exam make sure to write this)

Question 21

if E cell is positive then

Answer 21

the reaction written from left to right in the cell diagram is thermodynamically feasible since entropy will be positive

Question 22

if E cell is negative then

Answer 22

the reaction will be thermodynamically feasible from right to left in the cell diagram

Question 23

what is the reaction between K and E cell

Answer 23

ln K = nFEcell/ RT (derivation page 171)