Question 6
Write the formulae for the following compounds:
(a) Mercury(II) chloride
(b) Nickel(II) sulphate
(c) Tin(IV) oxide
(d) Thallium(I) sulphate
(e) Iron(III) sulphate
(f) Chromium(III) oxide
The representation of a molecule in terms of the symbols of the constituting atoms is called its chemical formula.
Rules for building the formula for a compound:
1) Write side by side the symbols of the radicals involved, with their valencies at the top, the positive radical to the left & the negative radical to the right.
2) Remove the common factor, if any, to get a simple ratio of the valencies of combining radicals.
3) Criss cross the valencies i.e, shift the valencies cross wise to the lower right of radical.
(a) Mercury (II) chloride:
HgCl2
(b) Nickel (II) sulphate:
NiSO4
(c) Tin (IV) oxide:
SnO2
(d) Thallium (I) sulphate:
Tl2SO4
(e) Iron (III) sulphate:
Fe2(SO4)3
(f) Chromium (III) oxide:
Cr2O3
