Monday, January 31, 2011


This class, we learned three new types of reactions: Double Replacement, Combustion, and Neutralization

Double Replacement

     Bee Butterfly + Sun Leaf -> Bee Leaf + Sun Butterfly

Yea I know that example made 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 K3PO3Cu(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.


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


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) -> CO2 4 H2O
This is a tutorial video on how to predict double replacement reactions. The video only gets useful around 1:40

Thursday, January 27, 2011


Heyy guys, before I start ranting about the types of reactions, I'll let you talk first. So, how's life? Is Sally doing good? I heard your rabbit passed away : ( I'm so sorry. Anything else? No? Alright let's get started.

SO, today we learned about three types of reactions: Synthesis, Decompositions, and Single Replacement.

                                                        skinny bird + worm = fat bird 

What you see above is an example of a synthesis reaction. A synthesis reaction is a reaction that combines two or more reactants to form one product.
The general formula is:
A + B = AB

Lets use an example that doesn't involve starving animals:
Ex 1/  8 Fe +  1 S8 -> 8  FeS
Ex2/  2  Na +  1 Cl2 ->  2 NaCl

                                                      Egg -> Shell + Turtle

A decomposition reaction is a reaction that breaks down one reactant into two or more products.
The general formula is:
A -> B + C

Ex 1/  2 NaCl ->  2  Na +  1  Cl2
Ex 2/  1  MgS ->  1  Mg +  1  S

Single Replacement
                             Hot guy + Scrawny Guy and Girl = Hot guy and Girl + Scrawny Guy

A single replacement reaction is one where an element replaces an ion in an ionic compound. Metal elements replace positive ions and non-metal elements replace negative ions.
The general formula is:
A + BC -> AC + B (A = metal)
A + BC -> BA + C (A = non-metal)

Ex 1/Ba +  1 Ni3(PO4)2 -> Ni +  1 Ba3(PO4)2
Ex 2/ 2 Hg +  1 Sn(SO4)2 ->  1 Sn +  2 HgSO4

After we learned this, our lovely teacher gave us a WONDERFUL sheet called  the "Activity Series". This table helps to predict whether the single replacement has a reaction or not. Before, we just assumed that it did but NOW, our whole perspective on life has changed.

Some metals are more reactive than other metals, and similarly some non-metals are more reactive than other non-metals

So, to read the "Activity Series", understand that an element higher up on the series replaces the ion below it on the table.

If the reactant is higher than the product, then it creates a reaction.
Ex /  2 Fe + CuCl2 -> Cu +  2 FeCl3
Look at Cu and Fe. Which one is higher on the table? Iron is higher, and iron is the product, meaning there IS a reaction. 

Ex/  1 Cl2  2 KBr ->  2 Br2 1 KCl

Look at Br and Cl. Which one is higher on the table? Chlorine is higher, and chlorine is the reactant, meaning there IS NOT a reaction. Too bad so sad.

This is a tutorial for single replacement reactions

Well thats all for now people : )

Monday, January 24, 2011


Okay, so let's admit it; we're all pretty much out of it. Now that our huge test is over, we all tend to relax. But please, in the midst of relaxing, please take a while to ponder about your past... Moreover, a specific past... Oh, okay, fine, I'll give it to you: SCIENCE TEN. I know you thought it was over and done with, but let's just say for the time being, it has come back to haunt you.

Remember that Law about conserving mass and energy? Well, here, it comes to play; each side of a chemical reaction has to balance out to the same amount of atoms and particles and whatnot. Oh, and don't forget the mass. I know this sounds overwhelming, but wait 'till you get to the translating form a word equation. Let's just start with a simple equation:
       Ex1/ C3H8 + O2 ---> H2O + CO2    Now this is obviously unbalanced (zomg, the font randomly changed)
There are three carbons on the left, but only one on the right.
There are eight hydrogens on the left but only two on the right.
There are two oxygens on the left but three on the right.


We all have to start off somewhere. And here, we just have to start with elements that only appear once on each side. In this case, carbon would be the first. Since there are 3 on the left, in order to balance it, we need to put 3 as a coefficient (for carbon) on the right to balance it up. Next, we'd look at Hydrogen. Since there are already 2 on the right side, we have to increase Hydrogen atoms using multiples of 2. Therefore the coefficient will be 4 on the right for water. Then all we do is balance oxygen. Your final equation should look like this:

C3H8 + 5O2 ---> 4H2O + 3CO2  (WOOHOO!)

Thursday, January 13, 2011

Diluting Solutions

Chemicals are usually shipped in their most concentrated form for convenience and transportation. 
We do not usually use the chemicals with that concentration, so we need to dilute them.

Key Idea: The moles of solute is constant before AND after diluting. (moles before = moles after)

M1L1 = M2L1

We can use this formula to find any one of those 4 pieces of information, as long as we have the other three.

Example: Concentrated HCl is at 11.6 mole/L. How would you make 250mL of 0.500 mole/L HCl?

You see you already have the 3 pieces of information that you need to determine what's unknown.

L1 = M2 x L2

(I just rearranged the formula to help us find what we are looking for, which was the volume that we began with.)

L1 = 0.500mole/L HCl x 250mL
11.6mole/L HCl

= 11mL

Now we know that we began with 11mL of solute. 

Are you this intense when it comes to Chemistry?

Wednesday, January 5, 2011

Molarity + A Cool Video!

We know, we've been showing you some pretty questionable videos lately. We're not really sure if they were much help, but we tried our best. Anyways... today we have something extremely rare and special to show you. It's a ... REALLY GOOD VIDEO. :) It's not some random Youtube video... it was made and customized for YOU GUYS!

Click the title of the video if you want to watch a version on Youtube that isn't covered by the side bar on the right.

Tuesday, January 4, 2011

Happy New Year! (Bonus Video!)

Hey everyone! 2011 has officially arrived, and today was the first day of school this year. It's the perfect time for you to turn over a new leaf (if you need to), or to continue your journey to become the very best that you can be. :)

Here's a special video that helped us remember some great memories that we had last year.

What NOT To Do During A Chemistry Lab!