Redox reactions using oxidation numbers
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This document discusses identifying redox reactions using oxidation numbers. It provides examples of assigning oxidation numbers to determine if a reaction is redox. A redox reaction is identified when oxidation numbers change for an element. The first reaction provided is a redox reaction where bromine is oxidized and chlorine is reduced. The second reaction shown is determined to not be a redox reaction because no oxidation numbers change. Multiple choice questions are given at the end to test identifying redox reactions.
Redox reactions using oxidation numbers
- 1. REDOX REACTIONS USING OXIDATION NUMBERS
- 2. Identifying Redox Reactions The change in oxidation number can be used to identify whether each reaction is a redox reaction or a reaction of some other type. If a reaction is a redox reaction, identify the element reduced, the element oxidized. a. Cl2(g) + 2NaBr(aq) → 2NaCl(aq) + Br2(aq) b. 2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l)
- 3. Applying oxidation numbers to the equation a. Assign oxidation numbers. 0 +1 –1 +1 –1 0 Cl2(g) + 2NaBr(aq) → 2NaCl(aq) + Br2(aq) If changes in oxidation number occur, the reaction is a redox reaction
- 4. The oxidation numbers have increased and decreased for bromine and chlorine respectively • This is a redox reaction. • The chlorine is reduced. • The bromide ion is oxidized. 0 +1 –1 +1 –1 0 Cl2(g) + 2NaBr(aq) → 2NaCl(aq) + Br2(aq)
- 5. Let us look at another example. Assign oxidation numbers. +1 –2 +1 +1 +6 –2 +1 +6 –1 +1 –2 2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l)
- 6. Calculate the change (if any) in the oxidation numbers • There was no change in any of the elements oxidation numbers. • This is not a redox reaction. +1 –2 +1 +1 +6 –2 +1 +6 –1 +1 –2 2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l)
- 7. Which of the following are redox reactions? 1. NH3 + HCl → NH4Cl 2. SO3 + H2O → H2SO4 3. NaOH + HCl → NaCl + H2O 4. H2S + NHO3 → H2SO4 + NO2 + H2O
- 8. Did you get them correct? 1. NH3 + HCl → NH4Cl 2. SO3 + H2O → H2SO4 3. NaOH + HCl → NaCl + H2O 4. H2S + NHO3 → H2SO4 + NO2 + H2O