Chemistry 30

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1. For each of the following reactions, complete the summary table below the equation. If an element does not undergo any change, leave the last two columns blank

a. 4 HCl + O → 2 HO + 2 Cl

element	Initial Ox. No		Final Ox. No.	e - gained or lost	Oxidized or reduced	Agent
H	+1	→	+1	0	--	--
Cl	-1	→	0	1	oxidized	reducing agent
O	0	→	-1	2	reduced	oxidizing agent

b. 4 Al _(s) + 3 O_{2 (g)} → 2 Al₂O₃

element	Initial Ox. No		Final Ox. No.	e - gained or lost	Oxidized or reduced	Agent
Al	0	→	+3	3	oxidized	reducing agent
O	0	→	-2	2	reduced	oxidizing agent

c. Fe_(s) + SnCl_{2 (aq)} → FeCl_{2 (aq)} + Sn_(s)

element	Initial Ox. No		Final Ox. No.	e - gained or lost	Oxidized or reduced	Agent
Fe	0	→	+2	2	oxidized	reducing agent
Sn	+2	→	0	2	reduced	oxidizing agent
Cl	-1	→	-1	--	--	--

d. PbO₂ + 4 HI → I₂ + PbI₂ + 2 H₂O

element	Initial Ox. No		Final Ox. No.	e - gained or lost	Oxidized or reduced	Agent
Pb	+4	→	+2	gain 2 e -	reduction	oxidizing agent – PbO2
O	-2	→	-2	0
H	+1	→	+1	0
I (to I2)	-1	→	0	lose 1	oxidation	reducing agent – HI
I (to PbI2)	-1	→	-1	0

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2. For each of these reactions, determine whether or not it is a redox reaction. If any are, identify oxidizing and reducing agents in those reactions.

a. CaBr₂ + Pb(NO₃)₂ → PbBr₂ + Ca(NO₃)₂

element	Initial Ox. No		Final Ox. No.	e - gained or lost	Oxidized or reduced	Agent
Not a redox reaction – no substance undergoes a change in oxidation number.

b. P₄ + 5O₂ → P₄O₁₀

element	Initial Ox. No		Final Ox. No.	e - gained or lost	Oxidized or reduced	Agent
P	0	→	+5	5	oxidized	reducing agent
O	0	→	-2	2	reduced	oxidizing agent

c. SnCl₂ + 2 FeCl₃ → 2 FeCl₂ + SnCl₄

element	Initial Ox. No		Final Ox. No.	e - gained or lost	Oxidized or reduced	Agent
Sn	+2	→	+4	2	oxidized	reducing agent
Fe	+3	→	+2	1	reduced	oxidizing agent

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