Question

1. choose the best answer. which mnemonic device is used to help people remember how oxidation - reduction reactions proceed? oil rig oil gar lio rig rig oil 8) look at the oxidation numbers in this reaction. then choose whether or not oxidation - reduction takes place. 2al(s) + cr₂o₃(aq) → al₂o₃(aq) + 2cr(s) 0 +3 -2 +3 -2 0 no yes 9) find the oxidation number in the reaction. then, choose whether or not oxidation - reduction takes place. p₄o₁₀(s) + 6h₂o(l) → 4h₃po₄(aq) +3 -2 +1 -2 +1 +5 -2 yes no

Explanation:

Step1: Identify redox mnemonic

OIL RIG stands for Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons), the standard mnemonic for redox reactions.

Step2: Analyze reaction 8 redox status

• Al: Oxidation number from $0$ to $+3$ (loses electrons, oxidized)
• Cr: Oxidation number from $+3$ to $0$ (gains electrons, reduced)

Redox reaction occurs.

Step3: Analyze reaction 9 redox status

• P: Oxidation number $+5$ in $\text{P}_4\text{O}_{10}$ and $+5$ in $\text{H}_3\text{PO}_4$
• H: Oxidation number $+1$ in $\text{H}_2\text{O}$ and $\text{H}_3\text{PO}_4$
• O: Oxidation number $-2$ in all species

No oxidation number changes, so no redox reaction.

Answer:

1. OIL RIG
2. yes
3. no