Thursday, January 27, 2011

Reaction or No reaction?

Reactions, reactions, reactions...
That's all there is.
Let's start off by reviewing some really basis reactions.

1. Synthesis: A+B-->C
In synthesis reactions, reactants combine to form a single product.
eg. _8_Fe+_1_S8-->_8_FeS

2. Decomposition: A-->B+C
In decomposition, the product "decomposes" into the reactants.
eg. _2_H20--> _2_H2+_2_O

So far so good, right?
Now, the new stuff comes in.
When we did single replacement reactions before, we assumed a reaction would result.
Little did we know that this isn't always the case.

We are introduced to an important chart called the "Activity Series".
This sheet is not boyfriend material, and my first impression of it made me cringe.

The Activity Series ranks the elements in order of reactivity. An element higher up on series is able to replace the ion below the chart. Let's see how it's done.

Single Replacement Review:
if A (metal), then A+BC-->AC+B;
if A (non-metal), then A+BC-->BA+C

So, look at the activity series and consider this equation:

Cu + Fe(OH)3-->

1. Predict the products.

Cu + Fe(OH)3--> Fe + CuOH

2. Look at the activity series. Ask yourself "Is copper placed higher iron?"

The answer is no. Iron is placed higher than copper, so NO REACTION WILL OCCUR.

3. Balance the equation.

3Cu + Fe(OH)3--> Fe + 3CuOH

YAY. We're done!!

**Some things to remember:
Whatever element that is replacing the original element has to be higher than the original, or else a reaction will NOT occur.
If the replacement element is higher, rest assured. A reaction will occur.


Time for a song that is really educational. I mean, look at the title!!

"Chemicals React-Aly&AJ"

Good luck with the new material! (:

Written by Jialynn.

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