Limiting Factor

Every reaction has the "fuel" that keeps the reaction going.
We can think of the fuel as the limiting factor or the reactant that gets used up first in an experiment.
Once this reactant gets used up, the experiment stops.
The other reactant, is in excess or left over at the end of a reaction.
If you were to add more of the limiting factor to the reaction after it has stopped, the reaction would continue.

Chemical Equations

A chemical equation is like a math problem, but a little different.  Chemical equations show what happens when you put different substances together and shows what new substances are formed.
On the left side of the equation, is the reactants.  These are the substances that REACT together.  You put a + sign to separate the substances. Then, you put an arrow to the right.  The arrow means "yields" or "produces."
On the right side of the equation, is what is produced from this reaction or the Products. You also put a + sign to separate the products.
By knowing the reactants, you can predict the products.  From the law of conservation of energy, all of the elements that are represented on the reactant's side, will end up on the product's side, but rearranged to make new substances.
See the example below:

4 Hydrogens and 2 Oxygens -----> 4 hydrogens and 2 Oxygens


Another Example:

Ca(OH)₂ + CO₂ à CaCOз + H₂O

1 Calcium, 4 Oxygens, 2 Hydrogens ---> 1 Calcium, 4 Oxygens, 2 Hydrogens

Same amount on each side - no elements are added and no elements are taken away

Density

Density is a relationship of mass/volume.  The more mass an object (compared to its volume) has the higher its density is going to be.  The more volume an object has (compared to is mass) the lower its density is going to be.
We tested the density of liquids in class.  We have learned that the density of water is 1 g/mL.
From trials in labs, we have figured out that we need to isolate aspects when figuring out density.  For example, when figuring out the density of a liquid, we have to subtract the mass of the cylinder away from the mass of the liquid and the cylinder to figure out what the liquid's mass is.
We also explored density through displacement of solids.  Through this, we figure out the volume of a solid object by putting the object into a measured amount of water, then subtracting the starting height from the height of the water that is displaced.

Solutions...

There are many things that we have hit on with solutions.  Here are a few of the highlights:

• Solutions have two parts - solute (solid which dissolves) and the solvent (liquid which causes the dissolving)
• Dissolving is not a chemical reaction or a phase change
• During dissolving, the solvent breaks the bonds of the solute, which "carries away" the solute in the solvent
• Substances that don't dissolve are insoluble
• Solutions can be separated back into original states through filtering and evaporation