Question

show the formation of chemical formula of following compound using their ions

1. ammonium sulphate
2. aluminium sulphide
3. magnesium nitrate

Answer 1

1. (NH4)+ + (SO4)2-
valency +1 -2
on cross multiplication of the symbols with valencies we'll get
(NH4)2SO4
2. Al3+ + S2-
+3 -2
On cross multiplication we get
Al2S3
3. Mg2+ + ( NO3)1-
+2 -1
on cross multipication we'll get
Mg(NO3)2

Answer 2

Whenever we can make a chemical formula of a compound we have to use their cations and anions then we have to cross multiply their charges so that we will get the Chemical formula for that compounds.

Arrival of Chemical formula:

1. Ammonium sulphate

Ammonium ion can be written as $NH_4^{+}$

Sulphate ion can be written as $SO_4^{2-}$

Now we have to cross multiply the charges we will get $(NH_{4} )_{2} SO_{4}$

2. Aluminium sulphide

Aluminium ion can be written as $Al^{3+}$

Sulphide ion can be written as $S^{2-}$

Now we have to cross multiply the charges we will get $(Al} )_{2} S_{3}$

3. Magnesium nitrate

Magnesium ion can be written as $Mg^{2+}$

Nitrate ion can be written as $NO_3^{-}$

Now we have to cross multiply the charges we will get $Mg (NO_{3})_2$