SECTION B a(i)Define each of the following terms;... | WAEC SSCE - Chemistry - 2024 (Essay)

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SECTION B

a(i)Define each of the following terms;

I. Deliquescence II. efflorescence

(ii) Give one example of a substance that undergoes each of the processes in 2a(i)

b(i)What is meant by ionization energy?

(ii)The second ionization energy value of sodium is greater than the first ionization energy. Briefly give an explanation for this observation.

c(i) State Charles' law

(ii) Sketch a graph to illustrate Charles' law.

(iii) A gas occupies 150 cm\(^3\) at 21\(^0\)C. What would be its volume if the temperature is raised to 45\(^0\)C and the pressure is kept constant?

d(i)Write chemical equations to illustrate what happens when each of the following oxides is dissolved in water:

I. Sodium oxide;

II. Phosphorus(III) oxide;

III. Chlorine (VII) oxide

IV. Magnesium oxide

(ii) Arrange the solutions in 2d(i) in order of increasing acidity.

Answer

a(i)I. Deliquescence is the phenomenon where a solid substance absorbs moisture from the air and dissolves, turning into a liquid solution.

II. Efflorescence refers to the phenomenon or product of a substance losing water of crystallization, often resulting in a powdery or crusty deposit on a surface.

(ii)Examples of Deliquescence include; Calcium chloride (CaCl\(_2\)); Potassium hydroxide (KOH);Sodium hydroxide (NaOH); Magnesium chloride (MgCl\(_2\)); Zinc chloride (ZnCl\(_2\))

Example of Efflorescence include; washing soda, Glauber's salt, and copper sulphate, gypsum

b(i) Ionization energy is the minimum energy needed to remove an electron from a gaseous atom or ion, essentially measuring how strongly an atom holds onto its electrons.

(ii) The second ionization energy of sodium (Na) is higher than its first ionization energy because the second electron is removed from a positively charged ion (Na+), which experiences a stronger electrostatic attraction to the nucleus than the neutral atom.

c(i) Charles' law states that the volume of a given mass of gas is directly proportional to the temperature provided pressure remains constant.

(ii) A graph illustrating Charles' law: Volume on the y-axis and temperature on the -axis with a line intercepting the y-axis and drawn to the negative x-axis at - 273\(^0\)C.

(iii) Given:

V\(_1\) = 150 cm\(^3\) T\(_1\) = 21 + 273 = 294K

V\(_2\) = ? T\(_2\) = 45 + 273 = 318K

Using \(\frac{V_1}{T_1}\) = \(\frac{V_2}{T_2}\)

V\(_2\) = \(\frac{V_1}{T_1}\times{T_2}\)

V\(_2\) = \(\frac{150}{294}\times{318}\)

V\(_2\) = 162.24 cm\(^3\)

d(i) I. Na₂O + H₂O → 2NaOH.

II. P\(_4\)O\(_6\) + 6H\(_2\)O → 4H\(_3\)PO\(_3\)

III. Cl₂O₇ + H₂O → 2HClO₄.

IV. MgO + H₂O → Mg(OH)₂.

d(ii) Increasing acidity is arranged from NaOH < Mg(OH)₂. < H\(_3\)PO\(_3\) < HClO₄.

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