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17.1 Balancing Oxidation-Reduction Reactions
By the end of this section, you will be able to: lightning, static electricity, the current generated by a battery as it discharges, and many other influences are included in electricity.
The electric current is the flow or movement of charge.
The charge may be carried by electron or ion.
The charge of a protons is equal to the charge of an electron.
The SI unit of charge is the coulomb and the charge of a protons.
The SI base unit for electrical current is the ampere, which is a flow rate of 1 coulomb of charge per second.
It is necessary to keep a closed path in most chemical systems.
There is an electrical potential difference between two points in the circuit that causes the flow of charge.
The V is the SI unit of electrical potential.
When a coulomb of charge moves through a potential difference, it gains or loses energy.
Table 17.1 summarizes the information about electricity.
Electricity-related phenomena include lightning, static electricity, and current produced by a battery.
The OpenStax book is available for free at http://cnx.org/content/col11760/1.9 chemical equation was relatively simple.
The half-reaction method is used for balancing oxidation-reduction reactions.
The use of half-reactions is important for balancing more complicated reactions and it is also important because many aspects of electrochemistry are easier to discuss in terms of half-reactions.
There are no good alternatives to half-reactions for discussing what is happening in many systems.
acidic, basic, or neutral solutions are frequently used for chemical reactions.
The nature of the solution may be important when balancing oxidation-reduction reactions.
It helps to see the problem.
Each half-reaction contains the same element in two different states.
The iron lost an electron and underwent oxidation.
The reduction is not obvious, but the manganese gained five electrons.
It is possible to use hydrogen ion directly or as a reactant that reacts with oxygen to generate water.
In acidic solutions where the reactants or products contain hydrogen and/or oxygen, hydrogen ion is very important.
The oxidation half-reaction doesn't involve hydrogen or oxygen, so hydrogen ion isn't needed to balance.
Oxygen is involved in the reduction half-reaction.
Oxygen can be converted to water by using hydrogen ion.
The basic solution has a lower hydrogen ion concentration and a higher hydroxide ion concentration.
We will look at how basic solutions differ from acidic solutions after finishing this example.
It is easier to treat a neutral solution as acidic than it is to treat it as basic.
The iron atoms in the oxidation half-reaction are balanced, but the charges on the ion are not equal.
To balance the charge, it is necessary to use electrons.
The charge on an electron and the number of electrons are included in the charges.
The half-reaction is balanced if the atoms and charges balance.
electrons appear as products in oxidation half-reactions Since iron underwent oxidation, it is the reducing agent.
It is necessary to check for charge balance because the atoms are balanced.
There is a total charge on the left of the arrow and a total charge on the right.
It is necessary to add five electrons to the left side of Chapter 17 to achieve charge balance.
On the left side, electrons appear as reactants.
There are two balanced half-reactions.
The half-reactions can be combined with the electrons.
The electrons are lost during oxidation.
The electrons will cause a reduction.
The reduction half-reaction must have the same number of electrons as the oxidation half-reaction.
There is no excess or missing electrons.
The oxidation half-reaction requires one electron while the reduction half-reaction requires five.
The oxidation half-reaction by five and the reduction half-reaction by one are the lowest common multiples of one and five.
This is the equation in the acidic solution.
The most common error occurs during the multiplication of the individual half-reactions if something does not check.
We wanted the solution to be basic.
Basic solutions have excess hydroxide ion.
The hydrogen ion will react with the hydroxide ion to produce water.
The simplest way to generate the balanced equation in basic solution is to start with the balanced equation in acidic solution and convert it to the equation for basic solution.
It is important to exercise caution when doing this, as many reactants behave differently under basic conditions and metal ion will form as the metal hydroxide.
It is possible to balance any oxidation-reduction reaction with an acidic reaction and then convert the equation to a basic reaction.
If the basic reactants and products are the same as the acidic ones, this will work.
There are very few examples of basic and acidic reactions.
It is possible to balance a basic reaction as acidic and then convert it to basic.
To convert to a basic reaction, it is necessary to add the same number of hydroxide ion to each side of the equation.
Water is produced by combining hydrogen ion with OH-.
We can now try a basic equation.
When necessary, simplifying should be done.
It is necessary to remove one H2O from each side of the reaction arrows.
This is the overall equation in the basic solution.
An unbalanced oxidation half-reaction and an unbalanced reduction half-reaction are what this is.
The four oxygen atoms in the permanganate need to be converted into four water molecule.
The balanced equation is in acidic solution.
It is necessary to convert the four O atoms in the MnO - 4 minus the two O atoms in the MnO2 into two water molecule.
The balanced equation is in acidic solution.
The basic solution has a balanced equation in it.
In the type of solution indicated, balance the following.
The oxidizing agents are identified by Fe2+ + Ag.
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