Answer to Question #154253 in Organic Chemistry for 123

Question

1, Explain the role of a salt bridge in a voltaic cell

2, Assign oxidation numbers to the following compounds:

a. KClO3 b. NO3 c. CH3 CHO

3, Balance the following half-reaction in an acidic solution:

Cr₂ O₇^2- → Cr³⁺

Answer 1

1. Salt bridges complete the electrical circuit. They also allow the movement of ions from one solution to another without mixing of the two solutions and maintain electrical neutrality.
2. KClO₃: oxidation number of K is +1, oxidation number of Cl is +5, oxidation number of O is -2, the oxidation number of the compound (the sum) is 1+5-2*3=0. NO₃: oxidation number of N is +5, oxidation number of O is -2, the oxidation number of the compound (the sum) is 5-2*3=-1. C¹H¹₃C²H²O: oxidation number of C¹ is -3, oxidation number of H¹ is +1, oxidation number of C² is +1, the oxidation number of H² is +1, oxidation number of O is -2, the oxidation number of the compound (the sum) is -3+1*3+1+1-2=0.
3. Cr₂O₇^2– + 7H⁺ + 4e⁻ → 2Cr³⁺ + 3.5H₂O