Equation: Mno4-Mno4 + Divide Into Two Half Reaction?

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Examples and Solutions

Example 1: Given Equation: MnO4- + S2-  Mn2+ + S0 Balance the equation by using the ion-electron method.
Step 1 Oxidation: S2-  S0
Reduction: MnO4-  Mn2+ Divide into two half reactions. Identify the element that is being oxidized and the other being reduced. (Use the entire ion or molecule.)
Step
2 Oxidation: S2-  S0
Reduction: MnO4-  Mn2+ Balance all the elements (other than oxygen and hydrogen).
Step
3 Oxidation: S2-  S0
Reduction: 8H+ + MnO4-  Mn2+ + 4H2O Balance O and H. The oxidation requires neither O nor H, but the reduction equation needs 4H2O on the right and 8H+ on the left.
Step
4 Oxidation: S2-  S0 + 2e-
Reduction: 5e- + 8H+ + MnO4-  Mn2+ + 4H2O Balance with electrons critically.
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Step 1 Oxidation: Sn  S4+
Reduction: N5+  N4+

Divide into two half reactions. Identify the element that is being oxidized and the other being reduced. (Use the entire ion or molecule.)
Step
2 Oxidation: Sn  S4+ + 4e-
Reduction: N5+ + 1e-  N4+ Balance all the elements (other than oxygen and hydrogen) with their electrons critically.

Step
3 Oxidation: Sn  S4+ + 4e-
Reduction: 4N5+ + 1e-  4N4+ Equalize the loss and gain of electrons. In this case multiply the oxidation equation by 1 and the reduction equation by 4.
Step
4 Sn + 4HNO3  SnO2 + 4NO2 + H2O Transfer the coefficient that appears before each substance in the balanced redox equation to the original equation.
Step
5 Sn + 4HNO3  SnO2 + 4NO2 + 2H2O Balance the remaining elements that were not reduced nor oxidized to be able to get the final balanced equation.
Step
6 Sn + 4HNO3  SnO2 + 4NO2 + H2O
Containing 1 atom of Sn, 4 atoms of N, 12 atoms of O and 4 atoms of H for each side. Check if both sides have the same charge and number of atoms for each element.

Questions
1. What does RIG in the mnemonic devices OIL RIG means?
a.) “Reduction Is Gone”
b.) “Reduction Is Gain”
c.) “Reduction Is Go”
d.) “Reduction Is
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Who was the one that proposed the phlogiston theory?
a.) Johann Joachim Becher
b.) Antoine-Laurent Lavoisier
c.) Joseph Priestly
d.) Georg Ernst Stahl

4. What do you call the molecules or ions that receive electrons?
a.) Reducing Agents
b.) Combusting Agents
c.) Oxidizing Agents
d.) Redox Agents

5. Which of the following statements is true?
a.) The Oxidation State of the Oxidizing Agent increases as its substance is reduced.
b.) The number of Electrons of the Oxidizing Agent gained as its Oxidation State increased.
c.) The Substance of the Reducing Agent is oxidized as its number of electrons lost.
d.) The Oxidation State of the Reducing Agent decreases as its substance is reduced.

6. It corresponds to the quantity of electrons (e-) that a specific atom gains or loses.
a.) Oxidation State
b.) Oxidizing Agent
c.) Oxidation Reaction
d.) None of the above

7. Which of the following is not true:
a.) Fluorine has always an oxidation number of -1 in compounds.
b.) Elements in Group 17 have an oxidation number of -1 in binary metal compounds with metals or hydrogen.
c.) Oxidization State of Hydrogen generally is +1 in compounds.
d.) Elements in Group 15 have an oxidation number of +3 in binary metal compounds with metals or

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