Here is a game about balancing quations:
http://education.jlab.org/elementbalancing/index
Try it for fun!
Physical States
- (s) – solid
- (l) – liquid
- (g) – gas
- (aq) – aqueous : dissolved in water
Example:
H2(g) is read hydrogen gas
Writing unbalanced equations
- Write correct formulas for reactants and products.
- Include a yield arrow between them.
- Include states when they are known or given.
- Be careful of diatomics (Dr. HOBrFINCl)
Examples
- Solid mercury (II) oxide decomposes to produce liquid mercury and gaseous oxygen.
- Write formulas and check charges
Hg2+O2- Hg + O
- Add states
HgO(s) Hg(l) + O(g)
- Check HOBrFINCl
HgO(s) Hg(l) + O2(g)
Example 2
- Solid carbon reacts with gaseous oxygen to form gaseous carbon dioxide.
C(s) + O2(g) CO2(g)
You try it!
• Solid magnesium metal reacts with liquid water to form solid magnesium hydroxide and hydrogen gas.
- Solid aluminum dichromate decomposes to form solid chromium (II) oxide, gaseous nitrogen, and gaseous water.
- Gaseous ammonia reacts with gaseous oxygen to produce nitrogen monoxide and gaseous water
Balancing Chemical Equations
- Balanced equations have equal numbers of atoms on both sides of the equation.
- Once formulas have been written, the subscripts cannot be changed. This would change the substances formed.
- Balancing is done by adding coefficients, large numbers in front of the reactants or products. 2 H2O = 4 Hydrogen and 2 oxygen atoms.
- Coefficients in balanced equations must always be whole numbers in the lowest ratio possible.
Writing Balanced Equations
Fe(s) + O2(g) Fe2O3(s)
-Start with the most complex molecule and add coefficients.
4Fe(s) + 3O2(g) 2Fe2O3(s)
-Check that the coefficients are in the lowest ratio.
Balancing equations
-Write the unbalanced equation, leave a space in front of each molecule to add a coefficient.
___Fe(s) + ___O2(g) ___Fe2O3(s)
1 Fe 2
2 O 3
-Underneath the arrow, write the elements and the count for the reactant and product sides.
-As coefficients are added, change the count on each side until the numbers on each side are equal.
