High School Chemistry : Balancing Oxidation-Reduction Reactions
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Example Question #1 :Balancing Oxidation Reduction Reactions
What is the coefficient on sulfur dioxide if the following redox reaction is balanced in an acidic solution?
Balancing redox reactions involves the following steps:
1. Divide the reaction into oxidation and reduction half reactions and balance all atoms that are not oxygen and hydrogen:
2. Balance the oxygens by adding water molecules on the opposite side of the reactions:
3.通过增加质子氢平衡opposite side of the equation:
4. Add electrons in order to equal the charges on both sides of the equation:
5. In order to make the electron exchange equal in each half step, we must multiply the top half reaction by 3:
6. Add up the reactants and products while cancelling out substances on opposite sides of the reactions. For example: we will cancel the 6 water molecules as reactants and be left with only one water molecule as a product. In addition, only 2 protons will be left on the reactant's side after canceling the 12 from the product's side.
In the balanced redox reaction, the coefficient on sulfur dioxide is 3.
Example Question #1 :Balancing Oxidation Reduction Reactions
下列不平衡的氧化还原反应,many electrons are transferred and which chemical species is being oxidized?
One electron is transferred; Hg is oxidized
One electron is transferred; P is oxidized
Two electrons are transferred; Hg is oxidized
Two electrons are transferred; P is oxidized
Two electrons are transferred; Hg is oxidized
首先,我们需要独立给定的反应ion into the two half-reactions by identifying changes in oxidation number. In this case, mercury (Hg) and phosphorus (P) show a change in oxidation number. Mercury begins with an oxidation number of zero, and ends with an oxidation number of
Now we can begin to look at the half-reactions.
Balance the atoms.
Now balance the electrons. We know that each mercury atom loses one electron and each fluorine atom gains one electron.
我们可以看到,两个电子转变。都给我dentify the element being oxidized, we must find the element that is losing electrons. In this case, mercury is being oxidized.
Example Question #2 :Balancing Oxidation Reduction Reactions
Oxidation is the__________of electrons, reduction is the__________of electrons.
loss . . . loss
gain . . . gain
None of these; it depends on the reaction.
gain . . . loss
loss . . . gain
loss . . . gain
An oxidation-reduction (redox) reaction is a reaction where electrons are transferred between two substances. When an atom is oxidized, it is called the reducing agent, and it loses a number of electrons. Similarly, a reduced atom is called the oxidizing agent, and gains the same number of electrons. A popular mnemonic to help remember is OIL RIG, or Oxidation is Loss of electrons, Reduction is Gain of electrons.
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