1. Balancing Equations

2. Law of Conservation of Mass: In a chemical reaction, matter can be neither created nor destroyed. In a chemical reaction, matter can be neither created nor destroyed. In a chemical reaction, the amount of reactants always equals the amount of products. In a chemical reaction, the amount of reactants always equals the amount of products.

3. Balancing Equations In other words….Law of Conservation of Atoms: In other words….Law of Conservation of Atoms: The number of atoms of each type of element must be the same on each side of the equation. The number of atoms of each type of element must be the same on each side of the equation.

4. Photosynthesis

5. Balancing Equation Step 1: Count the atoms on Reactant side. Step 2: Count the atoms on the Product side Reactant side: 2 atoms H and 2 atoms O Product side: 2 atoms H and 1 atom O H 2 + O 2 H 2 O Is this a balanced equation? To find out…… Hydrogen oxygen water Not Balanced!!! Not Balanced!!!

6. Balancing Equations The subscripts cannot be changed. (changing subscripts would result in a new substance) H 2 + O 2 H 2 O H 2 + O 2 H 2 O What can we do to make the products match the reactants? Step 3: Determine which elements are unequal.

7. Balancing Equations H 2 + O 2 H 2 O H 2 + O 2 H 2 O If the subscripts cannot be altered, how can the atoms be made equal? If the subscripts cannot be altered, how can the atoms be made equal? Step 4: Adjust the number of molecules by changing the coefficients.

8. Balancing Equations Reactants: 2 atoms of H and 2 atoms of O Products: 4 atoms of H and 2 atoms of O O is balanced, but H is no longer balanced! What can we do?!!!! H 2 + O 2 2H 2 O H 2 + O 2 2H 2 O

9. Balancing Equations Reactant side: 4 atoms of H and 2 atoms of O Product side: 4 atoms of H and 2 atoms of O It’s Balanced! 2H 2 + O 2 2H 2 O 2H 2 + O 2 2H 2 O Add a coefficient!!!

10. Balancing Equations 2H 2 + O 2 2H 2 O Step 5: Double check your work when you are finished.

11. Let’s Practice…. Count atoms. Reactants:Products: N =N= H=H= N 2 + H 2 NH 3 N 2 + H 2 NH 3 Nitrogen + hydrogen ammonia Nitrogen + hydrogen ammonia Nothing is balanced!!!!

12. Balancing Equations Balance the nitrogen first by placing a coefficient of 2 in front of the NH 3. Balance the nitrogen first by placing a coefficient of 2 in front of the NH 3. N 2 + H 2 2NH 3 N 2 + H 2 2NH 3 Hydrogen is still not balanced. What coefficient should be add to balance the hydrogen?

13. Balancing Equations Try a 3 in front of H 2. Try a 3 in front of H 2. Reactant side: 2 atoms N, 6 atoms H Reactant side: 2 atoms N, 6 atoms H Product side: 2 atoms N, 6 atoms H Product side: 2 atoms N, 6 atoms H N 2 + 3H 2 2NH 3 N 2 + 3H 2 2NH 3 The equations is balanced!!!!!

14. Balancing Equations This method of balancing equations is the inspection method. This method of balancing equations is the inspection method. The method is trial and error. The method is trial and error. Let’s Practice. Let’s Practice.

15. Balance the formula equation. Step 1 – Count the atoms Reactants – K ___, P ___, O ___, H ___, Cl ___ Products - K ___, P ___, O ___, H ___, Cl ___ ____K 3 PO 4 +____HCl  ____KCl ____ H 3 PO 4 Which type of atom is unbalanced? Practice:

16. place a 3 in front of the KCl. place a 3 in front of the KCl. Count the number of atoms. Count the number of atoms. ____K 3 PO 4 +____HCl  3 KCl ____ H 3 PO 4 Potassium needs to be balanced!!! Reactants – K ___, P ___, O ___, H ___, Cl ___ Products - K ___, P ___, O ___, H ___, Cl ___ Is this equation now balanced? Now we need to fix Chlorine……

17. ____K 3 PO 4 + 3 HCl  3 KCl ____ H 3 PO 4 Place a 3 in front of HCl Place a 3 in front of HCl Count the number of atoms Count the number of atoms Reactants – K ___, P ___, O ___, H ___, Cl ___ Products - K ___, P ___, O ___, H ___, Cl ___ Now is the equations balanced? YES!!

18. Practice: ____C 3 H 8 + ____O 2  ____CO 2 +____ H 2 O Count the atoms: Reactants: C ___, H ____, O ___ Products: C ___, H ____, O ___ Let’s start with carbon Let’s start with carbon

19. ____C 3 H 8 + ____O 2  3 CO 2 +____ H 2 O Place a 3 in front of CO 2 Place a 3 in front of CO 2 Count the atoms: Count the atoms: Reactants: C ___, H ____, O ___ Products: C ___, H ____, O ___ Now let’s fix the hydrogen? What should we try? Now let’s fix the hydrogen? What should we try?

20. ____C 3 H 8 + ____O 2  3 CO 2 + 4 H 2 O Place a 4 in front of H 2 O Place a 4 in front of H 2 O Count the atoms: Count the atoms: Reactants: C ___, H ____, O ___ Products: C ___, H ____, O ___ Now for the oxygen's… what should we try? Now for the oxygen's… what should we try?

21. ____C 3 H 8 + 5 O 2  3 CO 2 + 4 H 2 O Place a 5 in front of the O 2 Place a 5 in front of the O 2 Count the atoms: Count the atoms: Reactants: C ___, H ____, O ___ Products: C ___, H ____, O ___ Now are we balanced?? Now are we balanced??

22. Are you up for a challenge?!!! Count atoms. Reactants: Ca – __ atoms, P – ___ atoms, O – ___ atoms; H – ___atoms, S – ___ atom Products: Ca – __ atoms, P – ___ atoms, O – ___ atoms; H – ___atoms, S – ___ atom __Ca 3 (PO 4 ) 2 +__H 2 SO 4 __CaSO 4 +__H 3 PO 4 Try this one! Where should be start?