Tuesday, January 25, 2011

Translating Word Equations + Review of Naming Compounds + Balancing Equations! by Bev & Jialynn

What does a chemical equation tell you?

-the chemicals that are reacting together
-the number of particles involved
-the type of particles involved (ie. atoms, ions, molecules)
-the number of moles per substance
-the reactants & the products
-the state of the substance (ie. solid, liquid, gas, or aqueous)

How do you write a chemical equation?

ex. solid sodium metal burns in chlorine gas to form solid sodium chloride

Sodium chloride = Na +1  +  Cl -1  =  NaCl
Chlorine gas = Cl2 (one of the 7 diatomics*)

Na + Cl2 --> NaCl

# of atoms on each side:

right:              left:
Na - 1           Na - 1
Cl - 1            Cl - 2

To balance the right side of the equation, there needs to be 2 chloride atoms.

Na + Cl2 --> 2NaCl

Count the atoms again:

right:               left:
Na - 2            Na - 1
Cl - 2             Cl - 2

Now add 2 in front of the sodium metal; therefore, the balance equation is:

2Na + 1Cl2 --> 2NaCl

And the coefficients cannot be reduced!

What are diatomics?

The diatomics are 7 special non-metals that always form a molecule of 2 when alone.  They are:

Hydrogen, oxygen, fluoride, bromide, iodide, nitrogen, chloride

The diatomics are in gas form & are expressed as H2, O2, F2, Br2, I2, N2, & Cl2 in word equations.

~~Here is a trick to remember the diatomics~~

HOFBrINCl ("Hoffbrinkle")


I Bring Clay For Our New House

and they form a "7" shape in the periodic table! :D

another note: When sulphur & phosphorous are by itself, it is expressed as

S8            and              P4

Some tips for balancing equations:
-treat chemicals that come in groups (NO3, PO4) like a whole (make sure to balance these first!)
-balance everything else before balancing H and O
**remember, the coefficients have to be a whole number!!

Try these on your own (and balance them):

1. __Pb+__O2-->__PbO2
2. Lithium + Magnesium chloride-->
3. Water+hydrogen-->
4. Hydrogen + nitrogen-->ammonia
5. Potassium+water-->potassium hydroxide+hydrogen



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