Problem 4.40


Write the balanced molecular and net ionic equations for each of the following neutralization reactions.

(a)Aqueous acetic acid is neutralized by aqueous potassium hydroxide.

Notice in an acid-base reaction that the acid transfers its proton (H+) to the base. In this case, acetic acid, CH3COOH, transfers its proton to OH-. A nice way to think about this is to write the reactants and switch the anions and cations to get the products:

write the reactants: CH3COOH(aq) + KOH(aq) ------>

split these up into their component ions: H+ + CH3COO- + K+ + OH- ------>

switch anions and cations and predict products: CH3COOH(aq) + KOH(aq) ---> KCH3COO(aq) + H2O(l)

The salt here is KCH3COO (potassium acetate). Note that the products of a neutralization reaction between an acid and a metal hydroxide produces water and a salt.

In net ionic form, we have

CH3COOH(aq) + OH-(aq) ---> CH3COO-(aq) + H2O(l)

note that we do not ionize the weak electrolyte (acetic acid) on the reactant side!

(b) Solid chromium (III) hydroxide reacts with aqueous nitric acid.

Again, we have an acid reacting with a base, so we will get water and a salt as products.

write out the reactants: HNO3(aq) + Cr(OH)3(s) ----->

switch partners to predict products, and balance: 3HNO3(aq) + Cr(OH)3(s) ----> Cr(NO3)3(aq) + 3H2O(l)

The salt here is chromium (III) nitrate. In net ionic form,

3H+(aq) + Cr(OH)3(s) ----> Cr3+(aq) + 3H2O(l)

as if you haven't heard it enough, here's the nag: don't ionize the solid reactant!

(c) aqueous hypochlorous acid and aqueous calcium hydroxide react.

Crank through this one yourself. Just remember that hypochlorous acid is a weak acid!!!! You should get

HClO(aq) + OH-(aq) --> H2O(l) + ClO-(aq)

for the net ionic equation.


If you have any questions or comments, reply to chapman@sou.edu
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Doug Chapman chapman@sou.edu 6/23/08