Redox Reactions

Question 1

Redox reactions

Answer 1

Oxidation-reduction reaction is a type of chemical reaction that involves a transfer of electrons between two species.

Question 2

Oxidation nr./state

Answer 2

Nr. of electrons an atom has to take, give or share with another atom in order to fill the valance shell.
A1 → looses 1 → +1
A2 → looses 2 → +2
A3 → looses 3 → +3
A4 → either 4 → +/-4
A5 → gains 3 → -3
A6 → gains 2 → -2
A7 → gains 1 → -1
A8 → has a full valance shell.

Question 3

Rules for assigning oxidation nr. to elements of group A (except carbon)

Answer 3

• Oxidation nr. of a single element is always 0. F.ex. Fe, Na, H2, O2, N3…
• Oxidation nr. of a monatomic ion equals the charge. F.ex. Na+ → +1, F- → -1, Ca2+ → +2.
• Fluorine F always -1
• Alkali metals (group 1A) always +1
• Alkaline earth metals (2A) always +2
• Oxygen -2 except H2O2 -1 and OF2 +2
• Hydrogen with +1 with non-metals, -1 with metals (A1,A2).
• ΣOxidation nr. of elements in a neutral compound: 0 (no +/-)
• ## ΣOxidation nr. of polyatomic ions: the charge of the ion (+/-)

Question 4

LEO

Answer 4

Loosing electrons is oxidation.
The nr. on the molecule increases: 0→+2, -1→0
Reducing agent.

Question 5

GER

Answer 5

Gaining electrons is reduction
The nr. on the molecule decreases 1→0
-1→-2
Oxidizing agent

Question 6

Reducing agent

Answer 6

Compound being oxidized (loosing electrons)

Question 7

Oxidizing agent

Answer 7

Compound being reduced (gaining electrons)

Question 8

Oxidation nr./state of Carbon

Answer 8

• Every C-H decreases the oxidation nr of C by -1
• Every C-O, C-N, C-F, C-Cl increases the oxidation nr. of C by +1
• C-C does nothing.

Question 9

Redox reaction in biochemistry

Answer 9

Oxidation: Reduction:
Gain in oxygen Loss of oxygen
Loss of hydrogen Gain in hydrogen
Loss of electrons Gain of electrons

Question 10

Redox reaction in Glucose breakdown (Cellular respiration)

Answer 10

C6H12O6 + 6O2 → 6CO2 + 6H20 + energy
Glucose looses H, Carbon is being oxidized, glucose is the reducing agent.
O receives H which means O is being reduced, O2 is the oxidizing agent.

Question 11

Electron carriers

Answer 11

NAD+ ↔ NADH
Reduced Oxidized
Oxidizing agent Reducing agent

NAD+ takes 2 electrons and a proton from another molecule to become NADH.
NADH looses 2 electrons and a proton to become NAD+