Balance the following reactions, identify the type of reaction and indicate which reactions are oxidation-reduction reactions. Also if you could...

Balanced Reactions:

Rxn 1: `~BaCl_2 + ~Na_2SO_4 -gt ~BaSO_4 + ~2NaCl`

Rxn 2: `~2AgNO_3 + ~Na_2CO_3 -gt ~Ag_2CO_3 + ~2NaNO_3`

Rxn 3: `~Cu(NO_3)_2 + ~Na_2CO_3 -gt ~CuCO_3 + ~2NaNO_3`

Rxn 4: `~2Al(NO_3)_3 + ~3Na_2CO_3 -gt ~Al_2(CO_3)_3 + ~6NaNO_3`

Rxn 5: `~H_2SO_4 + ~Na_2CO_3 -gt ~Na_2SO_4 + ~H_2O + ~CO_2`

Types of Reactions:

• All of the reactions can be classified as double replacement reactions. Double replacement reactions take the general form: AB + CD -> AD + CB. The reactants and products in a double replacement reaction are all compounds. In reaction 5, the original products in the reaction would have been the compounds: `~Na_2SO_4` + `~H_2CO_3` . The `~H_2CO_3` then decomposed into `~H_2O` + `~CO_2` .

• Reactions 1, 2, 3, and 4 can also be classified as precipitation reactions. You can identify a precipitation reaction by noticing that an insoluble product is formed from two ionic aqueous solutions.

• Reaction 5 can also be classified as an acid-base reaction. The reactant `~H_2SO_4` is an acid and the other reactant `~Na_2CO_3` is a base. We know that this is not a precipitation reaction because no insoluble products are formed.

• None of the reactions is an oxidation-reduction reaction because none of the oxidation numbers in any of the reactions change from the reactant to the product side of the equation.

Example: Let's work through an example using Reaction 1.

`~BaCl_2 + ~Na_2SO_4 -gt ~BaSO_4 + ~NaCl`

Balancing the Reaction:

Step 1: Make a list of the number of each type of atom on the reactant and product sides of the equation.

Reactants       Products

Ba: 1             Ba: 1

Cl: 2              Cl: 1

Na: 2             Na: 1

S: 1               S: 1

O: 4               O: 4

Step 2: Add coefficients to balance the number of atoms on both sides of the equation.

Notice that Cl is unbalanced. Ask yourself "What number can I place in front of the compound on the product side containing the Cl, that when multiplied by the subscript of Cl will equal 2?" The answer is 2. So, we will place a coefficient of 2 in front of NaCl on the product side of the equation. This changes the number of Cl atoms to 2 and also changes the number of Na atoms to 2.

`~BaCl_2 + ~Na_2SO_4 -gt ~BaSO_4 + ~2NaCl`

Reactants       Products

Ba: 1             Ba: 1

Cl: 2              Cl: 2

Na: 2             Na: 2

S: 1               S: 1

O: 4               O: 4

The reaction is now balanced.

Type of Reaction:

First, rule out that the reaction is an oxidation-reduction reaction by assigning each element in the reaction an oxidation number. The list of rules for assigning elements oxidation numbers can be found online or in your textbook. If there is no rule for a particular element, you must figure it out based on the total charge of the compound or polyatomic ion.

`~BaCl_2 + ~Na_2SO_4 -gt ~BaSO_4 + ~2NaCl`

On the reactant side of the equation, the oxidation numbers are:

Ba: +2 , Cl: -1, Na: +1, S: +6, O: -2

On the product side of the equation, the oxidation numbers are:

Ba: +2, Cl: -1, Na: +1, S: +6, O: -2

Since none of the oxidation numbers changed, the reaction is not an oxidation-reduction reaction.

The fact that both of the reactants are ionic aqueous solutions and that an insoluble product is formed, tells us that the reaction is a precipitation reaction. We also know that a reaction with the general form of AB + CD -> AD + CB, is an example of a double replacement reaction.