1. Notes Ch. 11.2b Types of Chemical Reactions
Chemistry

2. Single-Replacement Reactions
A single-replacement reaction is a chemical change in which one element replaces a second element in a compound.
In this type of reaction both the reactants and products are made of one element and a compound.

3. One metal can only displace another metal in a compound if it is more reactive. We use an activity series of metals. A reactive metal will replace any metal listed below it in the activity series.
So that means Iron will replace copper but iron cannot replace zinc because zinc is more reactive (it is above iron on the table).
A halogen (group 7) can also replace another halogen to form a compound. The activity of the halogens decreases as you go down Group 7A on the periotid table.

4. Examples:
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g)
Zn(s) + Cu(NO3)2(aq) → Cu(s) + Zn(NO3)2(aq)
Br2(aq) + NaI(aq) → NaBr(aq) + I2(aq)

5. Double-Replacement Reactions
A double-replacement reaction is an exchange of two positive ions between two compounds. This type of reaction usually occurs between two aqueous solutions and will produce a precipitate, a gas, or a molecular compound like water.

6. For a double-replacement reaction to happen one of these has to be true:
One of the products is only slightly soluble and precipitates from solution. Example:
Na2S(aq) + Cd(NO3)2 → CdS(s) + NaNO3(aq)
2. One of the products is a gas. Example:
2NaCN(aq) + H2SO4,(aq) → 2HCN(g) + Na2SO4(aq)
3. One product is a molecular compound, like water. Example:
Ca(OH)2(aq) + 2HCl(aq) → CaCl2(aq) + 2H2O(l)

7. Combustion Reactions
A combustion reaction is a chemical change in which an element or compound reacts with oxygen, producing energy usually in the form of heat and light (fire). A combustion reaction always has oxygen as a reactant.
Example:
2C8H18(l) + 25O2 (g) → 16CO2(g) + 18H2O(l)

8. Predicting the Products of a Chemical Reaction
The number of elements and/or compounds reacting is a good indicator of possible reaction type and possible products.
Take a look at pgs