Question

Element X is a metal with a valency 2. Element Y is a non-metal with a valency 3.
(a) Write equations to show how X and Y form ions.
(b) If Y is a diatomic gas, write the equation for the direct combination of X and Y to form a compound.
(c) Write two applications of electrolysis in which the anode diminishes in mass.
(d) If the compound formed between X and Y is melted and an electric current passed through the molten compound, the element X will be obtained at the _________ and Y at the __________ of the electrolytic cell. (Provide the missing words).

Answer 1

Element X is a metal with valency 2 and element Y is a non-metal with valency 3.
(a) X, being a metal, loses two electrons and forms $X^{2+}$ cation. The chemical equation is:
$X\stackrel{}{\to }{X}^{2+}+2{\mathrm{e}}^{-}$
Y, being a non-metal gains three electrons and forms $Y^{3-}$ anion. The chemical equation is:
$Y+3{\mathrm{e}}^{-}\stackrel{}{\to }{Y}^{3-}$

(b) If Y is a diatomic gas, then it will react with X to form compound $X_3{Y}_2$. The chemical equation is given as follows:
3 X + Y₂ →X₃Y₂

(c) Disclaimer: Any two of the mentioned application of electrolysis will be sufficient to answer the given question.
The applications of electrolysis in which the anode diminishes in mass are:
​ ​(i) Electrolytic refining of metals - Impure anode metal diminishes in mass during the process of electrolysis and ​ deposition of pure ​metal occurs at the cathode.
​(ii) Electroplating - The metal used for electroplating articles is made the anode, that diminishes in mass during the ​ ​ process of ​electrolysis and a thin layer of metal is deposited on the article that is made the cathode.
(iii) Extraction of metals - The anode is sometimes consumed by the gases or products liberated at anode.

(d) If the compound $X_3{Y}_2$ formed between X and Y is melted and an electric current passed through the molten compound, the element X, will be obtained at the cathode and Y, will be obtained at the anode of the electrolytic cell.