Chapter 10: Problem 14
Indicate whether each reaction is a redox reaction. If it is, which atom gets oxidized and which atom gets reduced? Consult the shortcut rules. \(2 \mathrm{NaBr}+\mathrm{MgO} \rightarrow \mathrm{MgBr}_{2}+\mathrm{Na}_{2} \mathrm{O}\)
Short Answer
Expert verified
This reaction is not a redox reaction, as there are no changes in the oxidation states of any element in the reactants or products. Therefore, there is no oxidation or reduction taking place, and we do not need to identify any atoms being oxidized or reduced.
Step by step solution
01
Identify the initial oxidation states of each element
In the reactants, we have NaBr and MgO. We will assign oxidation states to each element in these compounds:
- Sodium (Na) is in group 1 and has an oxidation state of +1.
- Bromine (Br) is in group 17 and usually has an oxidation state of -1.
- Magnesium (Mg) is in group 2 and has an oxidation state of +2.
- Oxygen (O) is in group 16 and usually has an oxidation state of -2.
So for the reactants, the oxidation states are:
NaBr: Na (+1), Br (-1)
MgO: Mg (+2), O (-2)
02
Identify the final oxidation states of each element
In the products, we have MgBr2 and Na2O. We will assign oxidation states to each element in these compounds:
- Magnesium (Mg) is in group 2 and has an oxidation state of +2.
- Bromine (Br) is in group 17 and usually has an oxidation state of -1.
- Sodium (Na) is in group 1 and has an oxidation state of +1.
- Oxygen (O) is in group 16 and usually has an oxidation state of -2.
So for the products, the oxidation states are:
MgBr2: Mg (+2), Br (-1)
Na2O: Na (+1), O (-2)
03
Compare the initial and final oxidation states
Now we will compare the oxidation states of each element in the reactants and products:
- Na: +1 in NaBr -> +1 in Na2O (No change in oxidation state)
- Br: -1 in NaBr -> -1 in MgBr2 (No change in oxidation state)
- Mg: +2 in MgO -> +2 in MgBr2 (No change in oxidation state)
- O: -2 in MgO -> -2 in Na2O (No change in oxidation state)
04
Determine if the reaction is a redox reaction
Since there are no changes in the oxidation states of any element in the reactants or products, this reaction is not a redox reaction.
05
Identify the atoms being oxidized and reduced if necessary
As this reaction is not a redox reaction, there is no oxidation or reduction taking place. Thus, we do not need to identify any atoms being oxidized or reduced.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Oxidation States
Understanding oxidation states is essential when analyzing chemical reactions, especially to determine if a given reaction is a redox process. Oxidation states, also known as oxidation numbers, are theoretical numbers assigned to individual atoms within a molecule or ion. These numbers represent the formal charges an atom would have if the compound was composed of ions. They help chemists keep track of electron movement during chemical reactions.
In general, the rules for determining oxidation states are as follows: Elements in their elemental form have an oxidation state of zero. The sum of oxidation states in a neutral compound is zero. For ions, the sum of oxidation states equals the charge of the ion. Alkali metals (group 1) have an oxidation state of +1, alkaline earth metals (group 2) have +2, and oxygen typically has -2, except in peroxides or when bonded to fluorine. Halogens (group 17) usually have -1, except when combined with oxygen or other halogens.
To effectively use oxidation states, one must be meticulous in assigning the correct numbers based on these rules and track any changes that occur during the course of a reaction. In the presented exercise, the oxidation states of the elements were determined before and after the reaction, revealing no change for any of the elements, thus indicating that this reaction is not a redox reaction.
In general, the rules for determining oxidation states are as follows: Elements in their elemental form have an oxidation state of zero. The sum of oxidation states in a neutral compound is zero. For ions, the sum of oxidation states equals the charge of the ion. Alkali metals (group 1) have an oxidation state of +1, alkaline earth metals (group 2) have +2, and oxygen typically has -2, except in peroxides or when bonded to fluorine. Halogens (group 17) usually have -1, except when combined with oxygen or other halogens.
To effectively use oxidation states, one must be meticulous in assigning the correct numbers based on these rules and track any changes that occur during the course of a reaction. In the presented exercise, the oxidation states of the elements were determined before and after the reaction, revealing no change for any of the elements, thus indicating that this reaction is not a redox reaction.
Oxidation Reduction
Oxidation-reduction, or redox, is a type of chemical reaction that involves the transfer of electrons between two substances. One substance gains electrons (reduction) while the other loses them (oxidation). These reactions are central to energy production in biological systems, battery operation, and many industrial processes.
An easy way to remember this concept is the mnemonic 'OIL RIG': Oxidation Is Loss, Reduction Is Gain. It refers to the loss or gain of electrons. When an atom undergoes oxidation, its oxidation state increases, whereas reduction entails a decrease in the oxidation state. For instance, a metal reacting with oxygen to form an oxide typically involves the metal being oxidized.
However, not all chemical reactions are redox reactions. Some involve the rearrangement of atoms without any change in their oxidation states, like in the solution example where sodium, bromine, magnesium, and oxygen all maintain their oxidation states from reactants to products. Conversely, in a true redox reaction, at least one element's oxidation state changes as a result of the reaction.
An easy way to remember this concept is the mnemonic 'OIL RIG': Oxidation Is Loss, Reduction Is Gain. It refers to the loss or gain of electrons. When an atom undergoes oxidation, its oxidation state increases, whereas reduction entails a decrease in the oxidation state. For instance, a metal reacting with oxygen to form an oxide typically involves the metal being oxidized.
However, not all chemical reactions are redox reactions. Some involve the rearrangement of atoms without any change in their oxidation states, like in the solution example where sodium, bromine, magnesium, and oxygen all maintain their oxidation states from reactants to products. Conversely, in a true redox reaction, at least one element's oxidation state changes as a result of the reaction.
Chemical Reactions
Chemical reactions are processes where reactants transform into products through the making and breaking of chemical bonds. These reactions can vary widely in nature—some release energy, others require energy, and they can occur spontaneously or need a catalyst. Identifying the type of chemical reaction helps chemists understand and predict the behavior and outcome of the reactants involved.
Common types of chemical reactions include synthesis, decomposition, single replacement, and double replacement reactions. The example provided in the textbook exercise resembles a double replacement reaction, where parts of two compounds swap places to form two new compounds. Here, NaBr and MgO react to produce MgBr2 and Na2O. Even though this is a chemical reaction, it lacks the characteristic electron transfer of a redox process.
In essence, while all redox reactions are chemical reactions, not all chemical reactions are redox reactions. The understanding of chemical reactions extends beyond just redox processes; it also encompasses other concepts like equilibrium, reaction kinetics, and thermodynamics, which altogether define the course and feasibility of the reactions in various contexts.
Common types of chemical reactions include synthesis, decomposition, single replacement, and double replacement reactions. The example provided in the textbook exercise resembles a double replacement reaction, where parts of two compounds swap places to form two new compounds. Here, NaBr and MgO react to produce MgBr2 and Na2O. Even though this is a chemical reaction, it lacks the characteristic electron transfer of a redox process.
In essence, while all redox reactions are chemical reactions, not all chemical reactions are redox reactions. The understanding of chemical reactions extends beyond just redox processes; it also encompasses other concepts like equilibrium, reaction kinetics, and thermodynamics, which altogether define the course and feasibility of the reactions in various contexts.