Question

Sir
I am Shaun job of class 9,I have a doubt regarding chemistry on the topic of ionisation
How many ions are formed by complete ionisation of one molecule of A​​​​​​l₂(SO₄)₃ in water .Is there any formulas for claculating the number of ions formed when some amount of substance is dissolved in any solvent.and does the solvent play any role in this?
Thank you Sir
Shaun

Answer 1

The number of ions formed when a substance is dissolved in a solvent depends on the ions involved to form the ionic compund. But this also depends upon the dissociation constant which you will be getting in class 11. Dissociation constant determines how much amount of the substance is dissociated in the solvent. But for the complete dissociation the number of ions formed only depends on the number of ions involved in the process of forming.

The formtion of the Al2(SO4)3 occurs by the acid base reaction of a weak base Al(OH)3 and strong acid H2(SO4).
When Al2(SO4)3 is dissolved in water then it gets dissociated into 2 mol of Al(OH)3 and 3 mol of H2(SO4).
This can be found out by seeing the molecular formula of the compound. At first the constituent ions are found in this case which are Al3+ ion and (SO4)2- ion. As Al2(SO4)3 contains 2 Al3+ ions and 3 moles of (SO4)2- ions so the total number of ions formed on the complete dissociation of the compund Al2(SO4)3 are 5.