Use Appendix E in the textbook. Which of the following substances can oxidize RuO42 - (aq) to RuO4 - (aq) under standard conditions? Use Appendix E in the textbook. Which of the following substances can oxidize to under standard conditions? Ni2 + (aq) I2 (s) Cr2O72 - (aq) ClO3 - (aq) Pb2 + (aq)

Cr₂O₇⁻² (aq) and ClO₃⁻ (aq)

Explanation:

At a redox reaction, one substance must be reduced (gain electrons) and others must be oxidized (lose electrons). To evaluate the potential of the substance to be reduced, it's placed a reaction, in standards conditions, with H₂.

The potential reduction is quantified by E°, and as higher is the value of E°, as easy is to the compound to be reduced. So, at a redox reaction, the compound with the greatest E° will be reduced, and the other will be oxidized, in a spontaneous reaction. The values of E° are:

RuO₄⁻ (aq) to RuO₄²⁻ (aq) E° = + 0.59 V (the reduction reaction is the opposite of the oxidation reaction).

Ni⁺² (aq) E° = - 0.257 V

I₂ (s) E° = + 0.535 V

Cr₂O₇⁻² (aq) E° = + 1.33 V

ClO₃⁻ (aq) E° = + 0.890 V

Pb²⁺ (aq) E° = - 0.125 V

So, the substances that have E° higher than the E° of the RuO₄⁻² (aq) are Cr₂O₇⁻² (aq) and ClO₃⁻ (aq), which are the substances that can oxidize RuO₄⁻ (aq) to RuO₄²⁻ (aq).