CHAPTER 18. REACTIONS IN AQUEOUS SOLUTION 18.3
There are exceptions to this and some molecular substanceswillform ions when they
dissolve. Hydrogen chloride for example can ionise to form hydrogen and chloride ions.HCl (g)+H 2 O(ℓ)→H 3 O+(aq)+Cl−(aq)You can try dissolving ionic compounds such as potassium permanganate, sodium hydrox-
ide and potassium nitrate in water and observing what happens.Exercise 18 - 1
1. For each of the following, say whether the substance is ionic or molecular.a. potassium nitrate (KNO 3 )
b. ethanol (C 2 H 5 OH)
c. sucrose (a type of sugar) (C 12 H 22 O 11 )
d. sodium bromide (NaBr)
2. Write a balanced equation to show how each of the following ionic com-
pounds dissociate in water.
a. sodium sulphate (Na 2 SO 4 )
b. potassium bromide (KBr)
c. potassium permanganate (KMnO 4 )
d. sodium phosphate (Na 3 PO 4 )
3. Draw a diagram to show how KCl dissolves in water.More practice video solutions or help at http://www.everythingscience.co.za(1.) 0075 (2.) 0076 (3.) 0077
Electrolytes, ionisation
and conductivity
ESAFP
You have learnt that water is a polar molecule and that it can dissolve ionic substances in
water. When ions are present in water, the water is able to conduct electricity. The solution
is known as an electrolyte.Chemistry: Chemical change 317