Question

What is formula for (1)sodium chloride,(2) Calcium flourine,(3) Mercury chloride

Answer 1

NaCl

CaF2

and HgCl Answer

Answer 2

The formula for (1) sodium chloride is NaCl, for (2) calcium flouride is CaF₂, and for (3) mercury chloride is HgCl or HgCl₂, depending upon the valency of Hg.

(1) sodium chloride

• Sodium chloride is formed by the combination of sodium and chloride ions.

• Now, the symbol for sodium ion is Na⁺ and that for chloride ion is Cl⁻.

• Both + and - charge get cancelled.

• We shall now write these ions together by exchanging the magnitude of charges on them, and writing them as subscripts, as    Na₁Cl₁ .

   

• When the subscript is one, it is understood and ignored in the formula.

• Therefore, we arrive at the final chemical formula for sodium chloride as NaCl.

(2) calcium flouride

• Calcium fluoride is made of calcium cation and fluoride anion.

• The symbol for calcium ion is Ca²⁺, and that for fluoride ion is F⁻.

• Exchanging the magnitude of charges, the ions are written together as CaF₂ as the chemical formula for calcium fluoride.

(3) mercury chloride

• Symbol for mercury ion - Hg⁺ (mercurous ion) or Hg²⁺ (mercuric ion)

• Symbol for chloride - Cl⁻

• For Hg⁺, the formula is HgCl.

• For Hg²⁺, the formula is HgCl₂.