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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