Select the correct answer.
Which element or compound has lost electrons in this oxidation-reduction reaction?
[tex]4 Li+2 CoO \rightarrow 2 Co+2 Li_2 O[/tex]
A. CoO
B. [tex]Li _2 O[/tex]
C. Li
D. Co
E. [tex]O[/tex]
Answer (2)
Determine the oxidation states of each element in the reactants and products.
Identify the element that has increased its oxidation state (lost electrons).
The element that has increased its oxidation state is the element that has been oxidized.
Lithium (Li) loses electrons and is oxidized, so the answer is Li. L i
Explanation
Analyzing the Reaction We are given the reaction 4 L i + 2 C o O → 2 C o + 2 L i 2 O and asked to identify the element or compound that has lost electrons. Losing electrons corresponds to oxidation. To determine which species has been oxidized, we need to determine the oxidation states of each element in the reactants and products.
Determining Oxidation States in Reactants In the reactants:
Lithium (Li) is in its elemental form, so its oxidation state is 0.
In Cobalt(II) Oxide (CoO), oxygen (O) has an oxidation state of -2. Since the compound is neutral, cobalt (Co) must have an oxidation state of +2.
Determining Oxidation States in Products In the products:
Cobalt (Co) is in its elemental form, so its oxidation state is 0.
In Lithium Oxide ( L i 2 O ), oxygen (O) has an oxidation state of -2. Since there are two lithium atoms and the compound is neutral, each lithium (Li) atom must have an oxidation state of +1.
Comparing Oxidation States Now, let's compare the oxidation states:
Lithium (Li) goes from 0 to +1 (loses an electron, oxidized).
Cobalt (Co) goes from +2 to 0 (gains electrons, reduced).
Oxygen (O) remains at -2.
Identifying the Oxidized Element Since lithium's oxidation state increases from 0 to +1, it loses electrons and is oxidized. Therefore, the correct answer is Li.
Examples
In the process of rusting, iron loses electrons to oxygen, forming iron oxide. This is an example of oxidation, where iron's oxidation state increases as it combines with oxygen. Similarly, in batteries, lithium loses electrons to facilitate the flow of current, demonstrating the principle of oxidation in a practical application.
In the reaction, Lithium (Li) transitions from an oxidation state of 0 to +1, indicating it loses electrons and is oxidized. Thus, the correct answer for the element that has lost electrons is Li. Therefore, the answer is option C: Li.
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