Return to lesson

The reaction of an Arrhenius acid like HBr and an Arrhenius base like Ca(OH)2 always forms water and a salt.

The total balanced equation between hydrobromic acid and calcium hydroxide is

hydrobromic acid	calcium hydroxide	YIELDS	calcium bromide	water
2 HBr(aq)	+ Ca(OH)2(aq)	---->	CaBr2(aq)	+ 2 H2O(l)
Strong acid	Strong base		Soluble salt	Nonelectrolyte molecule

Except for water, all of the reactants and products are strong electrolytes so the ionic equation is

2 H1+(aq)	+ 2 Br1-(aq)	+ Ca2+(aq)	+2 OH1-(aq)	--->	Ca2+(aq) -	+ 2 Br1-(aq) -	+ 2 H2O(l)

The Ca2+(aq) and Br1-(aq) - appear exactly the same on both sides of the equation (they are spectator ions) so they can be deleted to give the net ionic equation.

2 H1+(aq)	+ 2 Br1-(aq)	+ Ca2+(aq)	+2 OH1-(aq)	--->	Ca2+(aq) -	+ 2 Br1-(aq) -	+ 2 H2O(l)

The net ionic equation. The H1+(aq) and OH1-(aq) combine to form an H2O molecule; their bonding changes so they must be kept in the net ionic equation:

2 H1+(aq)			+2 OH1-(aq)	--->	-		+ 2 H2O(l)

This is the same net ionic equation for all strong acid and strong base neutralizations. All strong acids and bases dissociate 100%. The hydronium ion and hydroxide ion are "free" in the solutions.

 

 revised April 12, 2005 all rights reserved 1997-2005