Question

b. K2Cr2O7(aq)(ACIDIC)+Co(NO3)2(aq)

• Reduction Half Reaction

• Oxidation Half Reaction

• Overall Balanced Redox Reaction

• Explain occurrence or non-occurrence of reaction by calculating Ecell.

Answer 1

ANSWER:

K2Cr2O7 only could be converted into Cr+3. Then, Cr2O7-2 is reduced to Cr+3 and Co+2 is oxidized to Co+3. Ions K+ and NO3- does not participate in the reaction.

Reduction half reaction:

• Balance Cr atoms

• Balance O atoms (adding one molecule of water per missing O atom)

• Balance H atoms (adding one H+ ion per missing H)

• Balance charges (adding electrons)

Oxidation half reaction:

• Co atoms are balanced and there is neither O or H atoms. Balance charges

Overall balanced Redox reaction

• To get overall balanced reactions, we make that both half reactions have the same number of electrons

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or

Ecell => occurrence or non-occurence of reaction

The standard potential of each half reaction are:

The standard potential of cell is defined as

replacing by values we get

This cell has a negative potntial. This means that reaction is non-spontaneous and this reaction does not occurs.