The borohydride reducing agent is useful because semirreação diagrammed below sh

ID: 943538 • Letter: T

Question

The borohydride reducing agent is useful because semirreação diagrammed below shows low reduction potential:

H2BO3–(aq) + 5H2O(l) + 8e– BH4(aq) + 8 OH–(aq)

The borohydride ions may be used in the nickel deposition from a solution containing Ni2 +. The reaction between the borohydride ion and Ni 2 + is

(A) transfer with 2 moles of electrons for every mole of ion borohydride.

(B) because the potential Ni 2+ / Ni is smaller than the semirreação presented.

(D) because the boron oxidizes while nickel is reduced.

(E) the transfer of 8 moles of electrons for every mole of Ni 2+ ion.

answer : (C) the ratio of 4 mol to 1 mol Ni2 + ion borohydride.

explanation and proof

oxidation :

BH4(aq) + 8 OH–(aq) ---------------------> H2BO3–(aq) + 5H2O(l) + 8e–

Ni+2 + 2e --------------------------> Ni ) x 4

4 Ni+2 + 8 e- ------------------------> 4 Ni+2

overall reaction:

BH4(aq) + 8 OH–(aq) + 4 Ni+2 ---------------------> H2BO3–(aq) + 5H2O(l) + 4 Ni

1 mol BH4- = 4 mol Ni+2

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