Double Replacement
Yea I know that example made about...no sense at all but bear with me.
A double replacement reaction is a reaction between two ionic compounds usually in solution. The ions switch partners.
The general formula is:
AB + CD -> CB + AD
Ex / 2 K3PO3 + 3 Cu(NO3)2 -> 1 Cu3(PO3)2 + 6 KNO3
Now, like the single replacement, we actually have to figure out whether a reaction actually occurs. How do you do that? You use the "Table of Solubilities"
If the reactants change state during the reaction, there is a reaction occurring. If there is no change of state, then there is no reaction.
How to use the table:
Step 1: Find your negative ion on the left hand column
Step 2: Look for the positive ion in the list in the 2nd column
Step 3: Follow that to the next column and it may say either soluble or not soluble
If it is soluble, the compound is aqueous = (aq)
If it is not soluble, the compound is solid = (s)
Ex/ 2 BeI2(aq) + 1 Sn(NO3)4(aq) -> 2 Be(NO3)2(aq) + 1 SnI4(s)
The reaction above has a reaction because a precipitation occurs.
Combustion
A combustion reaction is a reaction where the reactants are the chemical to be burned and the oxygen that it reacts with. The oxygen atoms usually end up combined with more than one type of atom as products.
The general formula is:
AB + O2 -> AO + BO
Ex/ C4H8 + 6 O2 -> 4CO2 + 4H2O
Neutralization
A neutralization reaction is a double replacement reaction where acids react with bases to produce water and ionic salts.
The acids have an H and the bases have OH. Both should be aqueous solutions.
The general formula is:
HA + BOH -> H2O -> H2O + BA
Ex/ 1 C3H8(g) + O2(g) -> 3 CO2 + 4 H2O
http://www.youtube.com/watch?v=t4iJM84WHRQ&feature=relmfu
This is a tutorial video on how to predict double replacement reactions. The video only gets useful around 1:40
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