Balancing Chemical Equations Homework

							                    Balancing Chemical Equations Homework

Welcome to the wonderful world of balancing chemical equations.

Think about it like this…. You want to make a sandwich- you know that two pieces of
bread, 3 slices of meat, 1 slice of cheese and a pickle makes a sandwich so you start
with all those components on the table. Once you have put it all together it looks
different then when it was on the table (because now it’s a sandwich) but did you
lose any of the parts when you made it? Did you add any new parts to it? NO!! It’s
made up of the same number of each part (ie. you still have two pieces of bread) –
they’re just arranged differently. That’s the same thing as a chemical reaction. You
start with certain chemicals (made up of atoms) then you end with different
chemicals but they still have the same atoms they are just arranged differently!!

You’re going to be introduced to this concept through the pHET simulator entitled
Balancing Chemical Equations

http://phet.colorado.edu/en/simulation/balancing-chemical-equations



Go to Introduction and click Balance scales.

By pressing on the arrows beside the chemical formulas in the equation you can
change how many of each molecule there is.

Press one nitrogen gas. How many ammonia’s do you have to have so the nitrogen
balance scale is balanced? ______

Notice by adding ammonia’s the other balance scale representing hydrogen is
unbalanced. How many hydrogen’s do you have on the product side currently? _____

If you wanted the hydrogen balance scale to be balanced how many hydrogen gas
molecules would you need? ______

Once both scales are balanced fill in the following chart

         Element                 How many atoms in           How many atoms in
                                    reactants ?                  products?
        Nitrogen
        Hydrogen


Try it again with the separate water button. Determine how many of each atom you
need on both sides of the equation to get the scales to balance out.

         Element                 How many atoms in           How many atoms in
                                    reactants ?                  products?
         Oxygen
        Hydrogen


Click on combustion of methane. This one is a little trickier.

If you add one methane which balance scales become unbalanced? __________ and
________.

If you try to balance out carbon what other element are you adding? _____________

Why is oxygen so hard to balance out? __________

Once you have all three elements balancing on their scales fill in the following chart

         Element                 How many atoms in               How many atoms in
                                    reactants ?                      products?
         Carbon
        Hydrogen
         Oxygen


General question:

   1) When you try to balance out an element what can you change the numbers
      of?
   2) When you balance the scales what part of the chemical equation changes?