Question

Write the empirical formula for at least four ionic compounds that could be formed from the following ions:

OH−

,

Fe+2

,

NH+4

,

CrO−24

Answer 1

The ionic compounds are formed between an electropositive and an elrctronegative ion.

The charge of both the ions are balanced in a way that the overall molecule becomes neutral. I.e the net positive charge value should be equal to net negative charge value

1- Fe+2 + OH-

Here net charge on Fe is +2. So to balance it we need net negative charge of -2

So the possible combination is

Fe+2 + 2(OH)- ---------+> Fe(OH)2. Ferrus hydroxide

similarly

Fe+2 and CrO4 2-

Here already we have+2 charge and to balance it a -2 charge

So the possible ionic compound is-

Fe+2 + (CrO4)2- ---------->. Fe(CrO4). Ferous chromate

3-

Similarly

(NH4)+ + OH- -------->. NH4OH Ammonium hydroxide

2 (NH4)+ + (CrO4)2- -------->. (NH4)2(CrO4). Ammoniun chromate