Question

1. look at the oxidation numbers in this reaction. then choose whether or not oxidation-reduction takes place.

0 +3 -2 +3 -2 0
2al(s) + cr₂o₃(aq) → al₂o₃(aq) + 2cr(s)

yes
no

1. find the oxidation number in the reaction. then, choose whether or not oxidation-reduction takes place.

+5 -2 +1 -2 +1 +5 -2
p₄o₁₀(s) + 6h₂o(l) → 4h₃po₄(aq)

yes
no

Explanation:

Question 8

Step1: Analyze Al's oxidation state

Al starts as 0 (solid metal) and becomes +3 in $\ce{Al2O3}$. It loses electrons (oxidation).

Step2: Analyze Cr's oxidation state

Cr is +3 in $\ce{Cr2O3}$ and becomes 0 (solid metal). It gains electrons (reduction).

Step3: Determine redox

Since there's both oxidation (Al) and reduction (Cr), it's a redox reaction.

Step1: Check P's oxidation state

In $\ce{P4O10}$, P is +5. In $\ce{H3PO4}$, P is also +5.

Step2: Check H and O states

H is +1 (no change), O is -2 (no change) in all compounds.

Step3: Determine redox

No element changes oxidation state, so no redox.

Answer:

yes

Question 9