1. Balancing Chemical Equations

2. Balanced Chemical Equations Atoms can’t be created or destroyed in an ordinary reaction:  Law of Conservation of Matter – All the atoms we start with we must end up with (meaning: balanced!) A balanced equation has the same number of each element on both sides of the equation.

3. Steps for balancing: 1)Find the correct formulas and write a skeleton equation. 2)Count the number of atoms of each type on both sides. 3)Balance the elements one at a time by adding coefficients (the numbers in front) - save balancing the H and O until LAST! (hint: I prefer to save O until the very last) 4)Double-Check to make sure it is balanced.

4. Never change a subscript to balance an equation (You can only change coefficients) – If you change the subscript (formula) you are describing a different chemical. – H 2 O is a different compound than H 2 O 2 Never put a coefficient in the middle of a formula; they must go only in the front 2 NaCl is okay, but Na 2 Cl is not.

5. Example: F 2 + KCl Cl 2 + KF F = 2F = 1K = 1 Cl = 1Cl = 2

6. Example: F 2 + KCl Cl 2 + KF F = 2F = 1K = 1 Cl = 1Cl = 2 \ 2 2

7. Example: F 2 + KCl Cl 2 + KF F = 2F = 1K = 1 Cl = 1Cl = 2 \ 2 22

8. Practice Balancing Examples _Mg + _N 2  _Mg 3 N 2 Mg = N = Mg = N =

9. Practice Balancing Examples _P + _O 2  _P 4 O 10 P= O = P = O =

10. Practice Balancing Examples _Na + _H 2 O  _H 2 + _NaOH Na= H = O = Na= H = O =

11. Practice Balancing Examples _CH 4 + _O 2  _CO 2 + _H 2 O C= H = O = C= H = O =

12. Practice Balancing Examples _AgNO 3 + _Cu  _Cu(NO 3 ) 2 + _Ag Ag = NO 3 = Cu = Ag = NO 3 = Cu =