Question

What is the correct relationship between the pHs of isomolar solutions of sodium oxide $(p{H_1})$ , sodium sulphide $(p{H_2})$ , sodium selenide $(p{H_3})$ and sodium telluride $(p{H_4})$ ?
(A) $p{H_1} > p{H_2} \approx p{H_3} > p{H_4}$
(B) $p{H_1} < p{H_2} < p{H_3} < p{H_4}$
(C) $p{H_1} < p{H_2} < p{H_3} \approx p{H_4}$
(D) $p{H_1} > p{H_2} > p{H_3} > p{H_4}$

Answer 1

Hint : To answer this question, we first need to understand what is pH. pH is a scale used in chemistry to describe the acidity or basicity of an aqueous solution. The pH of acidic solutions is lower than that of basic or alkaline solutions. The pH scale is logarithmic, indicating the concentration of hydrogen ions in a solution in reverse.

Complete Step By Step Answer:
Sodium oxide - The chemical compound sodium oxide has the formula Na2O. Ceramics and glasses contain it. When water is added to sodium oxide, it produces NaOH, which is the base anhydride of sodium hydroxide. $N{a_2}O + {H_2}O \to 2NaOH$ The antifluorite structure is formed by the alkali metal oxides ${M_2}O$ .
Sodium sulphide - Sodium sulphide $(N{a_2}S)$ or its hydrate, $N{a_2}S.9{H_2}O$ , is a chemical compound with the formula $N{a_2}S$ . The hydrated and anhydrous salts are both colorless solids. They are soluble in water and produce strongly alkaline solutions. When $N{a_2}S$ and its hydrates are exposed to moist air, hydrogen sulphide is produced, which has a rotten egg odor.
Sodium selenide - Sodium selenide $(N{a_2}Se)$ is an inorganic sodium-selenium compound with the chemical formula $N{a_2}Se$ .
Sodium telluride - The chemical compound sodium telluride has the formula $N{a_2}Te$ . The conjugate base of the thermally unstable acid hydrogen telluride, this salt is usually made by reducing tellurium with sodium. Because of its sensitivity to air, $N{a_2}Te$ is a difficult material to work with.
When the aforementioned compounds are dissolved in water, they each form their own base. When these oxides are placed in water, their basicity decreases, and the basicity of the solution decreases as well.
$N{a_2}O + 2{H_2}O \to 2NaOH + {H_2}O$
$N{a_2}S + 2{H_2}O \to 2NaOH + {H_2}S$
$N{a_2}Se + 2{H_2}O \to 2NaOH + {H_2}Se$
$N{a_2}Te + 2{H_2}O \to 2NaOH + {H_2}Te$
Order of neutralization is
${H_2}Te > {H_2}Se > {H_2}S > {H_2}O$
So, the pH will vary as option (D)
So, the final answer is option (D) $p{H_1} > p{H_2} > p{H_3} > p{H_4}$ .

Note :
A chemical reaction in which an acid and a base react quantitatively with each other is known as neutralization or neutralization. In a water reaction, neutralization ensures that there are no extra hydrogen or hydroxide ions in the solution.