Reactions- L14

Question 1

Redox reactions in Acidic solutions

Answer 1

• NO3- will oxidize metals that H+ cannot
• NO3- + X ==> NO + X^ax
• nitrate==>nitrogen monoxide

Question 2

Balancing REDOX reactions in acidic solutions

Answer 2

1. Write the two unbalanced half-reactions
2. Balance all atoms except O and H
3. Balance O by adding H2O molecules
4. Balance for H by adding H+ ions
5. Balance the charge by adding electrons
6. Cross multiply to cancel electrons
7. Add half reactions and cancel things that are the same

Question 3

Common Reductions is Acidic Solutions

Answer 3

• Nitrate: NO3- (aq)==> NO(g)
• Permanganate: MnO4-(aq)==>Mn+2
• Dichromate: Cr2O7-2(aq)==>Cr+3(aq)

Question 4

Oxidation of Sulfite

Answer 4

• SO3-2==>SO4-2

- The oxidation number of sulfur increases from +4 to +6

Question 5

Oxidation of Hydrogen Peroxide

Answer 5

• H2O2(aq)==>O2(g)

- The oxidation number on oxygen increases from -1 to 0

Question 6

Substances with Lower (less positive) oxidation states than usual

Answer 6

• In C2O4-2, Carbon has an oxidation state of +3
• As carbon is in Group 4A, it would rather have an oxidation state of +4
• It will oxidize (lose electrons) to raise its oxidation sates
• C2O4-2(aq)==>CO2(g)

Question 7

What if you have a choice of two species that can be oxidized

Answer 7

• When compounds contain p or d block metals and nonmetals with less positive than haul oxidation states THE METAL WILL BE OXIDIZED
• SnCl2, Sn+2 will be oxidized to Sn+4

Question 8

to add oxygen

Answer 8

add H20

Question 9

to add H

Answer 9

add H+ ions

Question 10

Basic solutions

Answer 10

• have a high concentration of hydroxide ions (OH+)

Question 11

Common reduction in Basic Solutions

Answer 11

Permanganate: MnO4- (aq) ==> MnO2 (aq)

Question 12

Redox Reactions in Basic Solutions

Answer 12

• last step is to add OH- to Eliminate H+
• OH- added to H+ makes H2O
• OH- added to H2O makes H20 + OH- and H20 usually ends up canceling out

Question 13

Redox titrations

Answer 13

• Often used to determine the concentration of a species that can be oxidized in a solution
• A solution with a known concentration of a species that is easily reduced is added to a solution with an unknown concentration of a species that will be oxidized in the reaction
• A color change signals the arrival at the endpoint
• Equivalence point occurs when equal numbers of moles of the species being oxidized and the species being reduced have combined