Reduction A decrease in oxidation state

Reduction A decrease in oxidation state (a gain of electrons). 

Oxidation—an increase in oxidation state (a loss of electrons) Reduction—a decrease in oxidation state (a gain of electrons) The oxidizing agent accepts electrons. 

Reduction a decrease in oxidation state (a gain of electrons). (4.9 17.1) Rem a unit of radiation dosage that accounts for both the energy of the dose and its effectiveness in causing biological damage (from roentgen equivalent for man). (19.7)... 

Oxidation—an increase in oxidation state Reduction— a decrease in oxidation state... 

Whenever we run a reaction that involves a decrease in oxidation state, we say that a reduction has occurred. For example, converting a ketone or aldehyde into an alcohol ... 

Table 6.2). In general, XPS of fresh catalysts shows mainly oxidized vanadium (V ). After reduction treatments, a decrease in oxidation state is observed. However, the extent of reduction depends on a number of factors, such as reduction temperature, reducing agent and partial pressure of the reducing gas, as well as the method used to transfer the reduced sample to the measurement chamber. Ideally, contact with air should be minimized, or excluded if possible, to prevent re-oxidation of the catalyst when the sample is transferred from a reactor to the UHV measurement chamber. This problem can be circumvented by in situ instrumentation as discussed later.

Reduction can be defined as a gain of electrons or as a decrease in oxidation state. Explain why the two definitions mean the same thing, and give an example to support your explanation. 

Reduction can be defined as the gaining of electrons by an atom, molecule, or ion. Reduction may also be defined as a decrease in oxidation state for an element. This decrease occurs because of the gaining of one or more electrons (thus the definitions are the same). The following equation shows the reduction of sulfur S(s) -I- 2e S aq). 

Oxidation is an increase in oxidation state and corresponds to the loss, or apparent loss, of electrons. Reduction is a decrease in oxidation state and corresponds to a gain, or apparent gain, of electrons. 

A reaction involving an increase in oxidation state is called an oxidation. For example, when methanol is converted into formaldehyde, we say that methanol was oxidized. In contrast, a reaction involving a decrease in oxidation state is called a reduction. For example, when formaldehyde is converted into methanol, we say that formaldehyde was reduced. Let s get some practice identifying oxidations and reductions. 

Alcohols can be formed by treating a carbonyl group (C=0 bond) with a reducing agent. The resulting reaction involves a decrease in oxidation state and is called reduction. 

Recall from Section 4.9 that oxidation is the loss of electrons, and reduction is the gain of electrons. Recall also that we can identily oxidation-reduction reactions through changes in oxidation states oxidation corresponds to an increase in oxidation state and reduction corresponds to a decrease in oxidation state. For example, consider the following reaction between calcium and water ... 

Oxidation-Reduction Reactions Some General Principles— In an oxidation-reduction (redox) reaction certain atoms undergo an increase in oxidation state, a process called oxidation. Other atoms undergo a decrease in oxidation state, or reduction. Another useful view of redox reactions is as the combination of separate half-reactions for the oxidation and the reduction. 

In a complexation reaction, a Lewis base donates a pair of electrons to a Lewis acid. In an oxidation-reduction reaction, also known as a redox reaction, electrons are not shared, but are transferred from one reactant to another. As a result of this electron transfer, some of the elements involved in the reaction undergo a change in oxidation state. Those species experiencing an increase in their oxidation state are oxidized, while those experiencing a decrease in their oxidation state are reduced, for example, in the following redox reaction between fe + and oxalic acid, H2C2O4, iron is reduced since its oxidation state changes from -1-3 to +2. 

Another way to determine what is undergoing oxidation and what is undergoing reduction is by looking at the change in oxidation numbers of the reactant species. Oxidation occurs when there is an increase in oxidation number. In the example above, the Zn metal went from an oxidation state of 0 to +2. Reduction occurs when there is a decrease in oxidation number. Cu2+ went from an oxidation state of +2 to 0. In order to determine if a particular reaction is a redox reaction, determine the oxidation numbers of each element in the reaction. If at least one element changes oxidation number, it is a redox reaction. Refer to your textbook for rules in assigning oxidation numbers. 

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