The equation for the reaction between aluminium and copper (II) oxide is:
[tex]2 Al+3 CuO \longrightarrow Al_2 O_3+3 Cu[/tex]
Which statements about this equation are correct?
1. The oxidation number of the aluminium reactant is +2
2. The oxidation number of the aluminium in the product is +6
3. The oxidation number of the aluminium in the reactant is +2
4. The oxidation number of the copper product is 0.
Please mark 1 answer.
A. 1, 2, and 3
Answer (2)
The oxidation number of Al in the reactant is 0.
The oxidation number of Al in A l 2 O 3 is +3.
The oxidation number of Cu in the product is 0.
Only statement 4 is correct: 4
Explanation
Problem Analysis Let's analyze the given chemical equation and the oxidation numbers of the elements involved to determine which statements are correct.
Chemical Equation The chemical equation is: 2 A l + 3 C u O → A l 2 O 3 + 3 C u We need to determine the oxidation numbers of aluminium and copper in the reactants and products.
Oxidation Number of Al in Reactant
Oxidation number of aluminium (Al) in the reactant:
Aluminium in its elemental form (Al) has an oxidation number of 0 because it is not combined with any other element.
Therefore, statements 1 and 3, which claim the oxidation number of aluminium in the reactant is +2, are incorrect.
Oxidation Number of Al in Product
Oxidation number of aluminium (Al) in the product ( A l 2 O 3 ):
In A l 2 O 3 , oxygen (O) has an oxidation number of -2. Since there are three oxygen atoms, the total negative charge is -6.
To balance the charge, the two aluminium atoms must have a total positive charge of +6. Therefore, each aluminium atom has an oxidation number of +3.
Statement 2, which claims the oxidation number of aluminium in the product is +6, is incorrect.
Oxidation Number of Cu in Product
Oxidation number of copper (Cu) in the product:
Copper in its elemental form (Cu) has an oxidation number of 0 because it is not combined with any other element.
Therefore, statement 4, which claims the oxidation number of copper in the product is 0, is correct.
Conclusion Based on our analysis:
Statement 1 is incorrect.
Statement 2 is incorrect.
Statement 3 is incorrect.
Statement 4 is correct.
Therefore, only statement 4 is correct.
Examples
Understanding oxidation numbers is crucial in many real-world applications, such as designing batteries, preventing corrosion, and developing new chemical processes. For example, in the design of a battery, knowing the oxidation states of the materials involved helps predict the voltage and energy output of the battery. Similarly, in preventing corrosion, understanding how metals oxidize allows for the development of protective coatings that prevent the metal from losing electrons and degrading. In the equation, 2 A l + 3 C u O → A l 2 O 3 + 3 C u , we can see how aluminium is oxidized (loses electrons) and copper is reduced (gains electrons), which is a fundamental concept in electrochemistry.
In the given chemical reaction, aluminium's oxidation number in the reactant is 0, and in the product, it is +3. Copper in the product retains an oxidation number of 0. Hence, only statement 4 is correct.
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