Refer to page 79 of the Formulae and Tables booklet when answering this question. (a) What is the number of electrons in each of the main energy levels (shells) (i) in an oxygen atom? (ii) in a magnesium atom? (b) Define (i) oxidation, (ii) reduction, in terms of electron transfer. (c) When magnesium metal burns in air with a bright white flame, the following reaction takes place forming magnesium oxide, an ionic substance. \[ 2Mg + O_2 \rightarrow 2MgO \] (i) Which element is reduced? (ii) Which substance is the reducing agent? (d) When a piece of magnesium metal is placed in a blue solution of copper(II) sulfate, the following reaction takes place, the blue colour fades, and copper metal is formed. \[ Mg + Cu^{2+} \rightarrow Mg^{2+} + Cu \] What does this result tell you about how easily magnesium metal is oxidised compared to copper metal?

Leaving Cert Chemistry Oxidation & Reduction: Refer to page 79 of the Formulae

Refer to page 79 of the Formulae and Tables booklet when answering this question - Leaving Cert Chemistry - Question 9 - 2020

Question 9

Refer to page 79 of the Formulae and Tables booklet when answering this question. (a) What is the number of electrons in each of the main energy levels (shells) (i)... show full transcript

Worked Solution & Example Answer:Refer to page 79 of the Formulae and Tables booklet when answering this question - Leaving Cert Chemistry - Question 9 - 2020

Step 1

What is the number of electrons in each of the main energy levels (shells) (i) in an oxygen atom?

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Answer

An oxygen atom has a total of 8 electrons, distributed in the main energy levels as follows: 2 electrons in the first shell and 6 electrons in the outer (valence) shell.

Step 2

What is the number of electrons in each of the main energy levels (shells) (ii) in a magnesium atom?

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Answer

A magnesium atom has a total of 12 electrons, distributed as follows: 2 electrons in the first shell and 8 electrons in the outer (valence) shell.

Step 3

Define (i) oxidation,

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Answer

Oxidation is defined as the loss of electrons by a substance during a chemical reaction.

Step 4

Define (ii) reduction,

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Answer

Reduction is defined as the gain of electrons by a substance during a chemical reaction.

Step 5

When magnesium metal burns in air with a bright white flame (i) Which element is reduced?

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Answer

In the reaction of magnesium with oxygen, the oxygen (O) is the element that is reduced.

Step 6

When magnesium metal burns in air with a bright white flame (ii) Which substance is the reducing agent?

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Answer

The reducing agent in this reaction is magnesium (Mg), as it donates electrons to oxygen.

Step 7

When a piece of magnesium metal is placed in a blue solution of copper(II) sulfate, what does this result tell you about how easily magnesium metal is oxidised compared to copper metal?

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Answer

The reaction indicates that magnesium is more easily oxidised than copper, as it displaces copper from the copper(II) sulfate solution.

Refer to page 79 of the Formulae and Tables booklet when answering this question - Leaving Cert Chemistry - Question 9 - 2020

Worked Solution & Example Answer:Refer to page 79 of the Formulae and Tables booklet when answering this question - Leaving Cert Chemistry - Question 9 - 2020

What is the number of electrons in each of the main energy levels (shells) (i) in an oxygen atom?

What is the number of electrons in each of the main energy levels (shells) (ii) in a magnesium atom?

Define (i) oxidation,

Define (ii) reduction,

When magnesium metal burns in air with a bright white flame (i) Which element is reduced?

When magnesium metal burns in air with a bright white flame (ii) Which substance is the reducing agent?

When a piece of magnesium metal is placed in a blue solution of copper(II) sulfate, what does this result tell you about how easily magnesium metal is oxidised compared to copper metal?

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