Site hosted by Angelfire.com: Build your free website today!

Chemical Reactions =)

I be working on me website, all the ding-dong day....
Hullo all!! =) this is the Chemical Reactions page! Come and vist us anytime, we're just starting so I'm in the process of creating it so be sure to visit us again soon. Come back anytime! (perferrably when we're done =P
What is a Chemical Reaction?
Basically a chemical reaction is a reaction that forms because of the combination of chemicals. We use chemical equations to show the changes that take place during a chemical reaction.
Mainly, there are four types of chemical reactions:
    Synthesis Reaction Decomposition Reaction Single Replacement Reaction Double Replacement Reaction



Synthesis Reaction - In a synthesis reaction, two or more elements or compounds combine to make one compound.
For example:
Mg + Cl2 -> MgCl2

The Magnesium(Mg) and Chlorine(Cl) were seperate in the reactants side, but when they are combined, a synthesis reaction occurs and they combine to form one compound (MgCl2). The reason there are co-efficients and subscripts is covered in Balancing equations and they are there basically because you must first balance the equations... but that's another story... =)


Decomposition Reaction - Decomposition means "breaking down" and in a deomposition reaction compounds simply break down into two or more parts.
For example:
NaCl -> Na + Cl
Using Salt(Sodium Cholride; NaCl) as our example, we can see that the salt has gone through a decomposition reaction. On the reactants side is the compound NaCl, but when it goes through the decomposition reaction, it breaks down into its seperate parts, Sodium(Na) and chlorine(Cl).


Single Replacement Reaction - In a single replacement reaction, an elements replaces with one another element in a compound.
For example:
BeF2 + Mg -> MgF2 + Be
In this example, we have the compound Berylium Flouride(BeF2) and Magnesium(Mg) as the reactants. When going through the single replacement reaction, they yield MgF2 + Be. What happens is that the single element in the reactant, in our case Mg, replaces Be in BeF2 and in the final product, Be is alone. Basically, in single replacement reactions the compounds that form are always ionic because they need a negative-positive attraction to hold them together. Mg and Be are both positive and F2 is negative. Mg, since it is the single element, replaces the positive element in the compound. Therefore the product is MgF2 + Be.


Double Replacement Reaction - In a double replacement reaction, there are two compounds in the reactants side and the positive elements in the compounds replace each other.
For example:
3KOH + AlCl3 -> Al(OH)3 + 3KCl
In this equation we're working with Potassium(K) Hydroxide(OH) and Aluminum(Al) Chloride(Cl) as the reactants. The positive elements are K and Al and as you can see, they recombined with the negative elements, OH and Cl. Therefore the 3K recombines with Cl to form 3KCl and the Al recombines with OH to form Al(OH)3.

Don't forget to...

Make sure all of your equations are balanced!! Simply writing the chemical formula and switching around the elements does not make the chemical equation right. It MUST be balanced! =)



Extra Practice!
This is the "Extra Practice" Section. You'll be given chemical equations and you must identify which of the four Chemical reactions they fall under. Answers are located in the textboxes, just click and drag down. The first four problems will have explainations included. Enjoy =)

NOTE: Remember that all coefficients and subscripts are there because the chemical equations need to be balanced. Don't get them confused with the chemical reactions! Good luck!

#1: 3NaOH + FeCl3 -> 3NaCl + Fe(OH)3
#2: 2H2O -> 2H2 + O2
#3: P4 + 5O2 -> 2P2O5
#4: Zn + 2HCl -> ZnCl2 + H2
Okay now, these last four problems had explainations, but for the next couple problems, you'll have to figure them out on your own. Good luck and happy hunting! =)
#5: 4C + 6H2 -> 2C2H6O
#6: 2LiI + Pb(NO3)2 -> 2LiNO3 + Pb I2
#7: CdCO3 -> CdO + CO2
#8: SO3 + H2O -> H2SO4
Here's a special little section about combustion . Enjoy =)

Combustion:
Combustion is an exothermic reaction (meaning that it releases a lot of heat and light) that uses oxygen (O) to form the "oxides" in products . This may be a little hard to understand, but bear with it for a moment... Combustion is usally used to get the huge amounts of energy it creates. Here's an example of combustion in a chemical reaction: CH4 + 2O2 -> CO2 + H2O. See, the oxygen in the reactants (O2) switches to both parts of the products. Now the products have an element of oxygen. CO2 becomes carbon dioxide and 2H2O makes hydrogen oxide.

Page written by: Kim Yau (azncucumber@yahoo.com)


HOME