Question

The silicate anion in the mineral kinoite is a chain of three $Si{O}_4$ tetrahedral that share corners with adjacent tetrahedral. The mineral also contains $C{a}^{2+}$ ions, $C{u}^{2+}$ ions, and water molecules in a $1:1:1$ ratio. The mineral is :

• A. $C{a}_{2}C{u}_{2}S{i}_3{O}_{10}\cdot 2H_{2}O$
• B. $CaCuS{i}_3{O}_{10}\cdot H_{2}O$
• C. $C{a}_{2}C{u}_{2}S{i}_3{O}_8\cdot 2H_{2}O$
• D. $C{a}_{2}C{u}_{2}S{i}_3{O}_6\cdot 2H_{2}O$

Answer 1

Answer: (A)

$C{a}_{2}C{u}_{2}S{i}_3{O}_{10}\cdot 2H_{2}O$

Three $Si{O}_4$ tetrahedral that share corners with adjacent tetrahedral creates $S{i}_3{O}_{10}^{-4}$ anion.
So to form a neutral compound total poistive charge required is 4; also ratio of cations is 1:1 so compound is $C{a}_{2}C{u}_{2}S{i}_3{O}_{10}.2H_{2}O$.