balancing equations #1
Post on 22-Jan-2015
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How to balance chemical equations
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- 1. Balancing Equations Balancing, Writing, and Naming Equations
2. Balancing Equations 3. Balancing Equations
- Law of Conservation of Matter:
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- In a chemical reaction, matter can be neither created nor destroyed.
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- In a chemical reaction, the amount of reactants equal the amount of products.
4. Balancing Equations
- Paraphrase:
- Law of Conservation ofAtoms :
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- The number of atoms of each type of element must be the same on each side of the equation.
5. Balancing Equations
- Hydrogen and oxygen are diatomic elements.
- Their subscripts cannot be changed.
- The subscripts on water cannot be changed.
- Hydrogen + oxygenwater
- H 2 +O 2 H 2 O
6. Balancing Equation
- Count the atoms on each side.
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- Reactant side: 2 atoms H and 2 atoms O
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- Product side: 2 atoms H and 1 atom O
- H 2+O 2 H 2 O
7. Balancing Equations
- H 2+O 2 H 2 O
- If the subscripts cannot be altered, how can the atoms be made equal?
- Adjust the number of molecules by changing thecoefficients .
8. Balancing Equations
- Reactants:2 atoms of H and 2 atoms of O
- Products:4 atoms of H and 2 atoms of O
- H is no longer balanced!
- H 2 +O 2 2 H 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
- Its Balanced!
- 2 H 2+ O 2 2 H 2 O
10. Balancing Equations
- Count atoms.
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- Reactants:2 atoms N and 2 atoms H
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- Products:1 atom N and 3 atoms of NH 3
- N 2 +H 2 NH 3
- Nitrogen + hydrogenammonia
11. Balancing Equations
- Nothing is balanced.
- Balance the nitrogen first by placing a coefficient of 2 in front of the NH 3 .
- N 2 +H 2 2 NH 3
12. Balancing Equations
- Hydrogen is not balanced.
- Place a 3 in front of H 2.
- Reactant side:2 atoms N, 6 atoms H
- Product side:2 atoms N, 6 atoms H
- N 2 +3 H 2 2 NH 3
13. Balancing Equations
- Count atoms.
- Reactants:Ca 3 atoms, P 2 atoms, O 8 atoms; H atoms, S 1 atom, O 4 atoms
- Ca 3 (PO 4 ) 2 +H 2 SO 4 CaSO 4 +H 3 PO 4
14. Balancing Equations
- Side note on Ca 3 (PO 4 ) 2
- The subscript after the phosphate indicates two phosphate groups.
- This means two PO 4 3-groups with two P and eight O atoms.
15. Balancing Equations
- Ca 3 (PO 4 ) 2 +H 2 SO 4 CaSO 4+H 3 PO 4
- Count atoms in the product.
- Ca atoms 1, S atom 1, O atoms 4; H atoms 3, P atom 1, O atoms - 4
16. Balancing Equations
- In this equation, the ion groups do not break up.
- Instead of counting individual atoms, ion groups may be counted.
- Ca 3 (PO 4 ) 2 +H 2 SO 4 CaSO 4+H 3 PO 4
17. Balancing Equations
- Ca 3 (PO 4 ) 2 +H 2 SO 4 CaSO 4+H 3 PO 4
- Reactants:Ca 2+ 3, PO 4 3-- 2, H + 2, SO 4 2+- 1
- Products:Ca 2+- 1, SO 4 2-- 1, H +- 3, PO 4 3-- 1
18. Balancing Equations
- Balance the metal first by placing a coefficient of 3 in front of CaSO 4 .
- Products:Ca 3 atoms,SO 4 2-- 3 groups
- Ca 3 (PO 4 ) 2 +H 2 SO 4 3 CaSO 4+H 3 PO 4
19. Balancing Equations
- Three sulfate groups are needed on the reactant side so place a coefficient of 3 in front of H 2 SO 4 .
- 3H 2 SO 4gives 6 H +and 3 SO 4 2- .
- Neither phosphate nor calcium is balanced.
- Ca 3 (PO 4 ) 2 +3 H 2 SO 4 3 CaSO 4+H 3 PO 4
20. Balancing Equations
- A coefficient of 2 placed in front of H 3 PO 4which balances both hydrogen and phosphate.
- Ca 3 (PO 4 ) 2 +3 H 2 SO 4 3 CaSO 4+2 H 3 PO 4
21. Balancing Equations
- The sulfate group breaks up.Each atom must be counted individually.Ugh!
- Reactants:Cu 1, H 2, S 1, O 4
- Products:Cu 1, S 1, O - 4, H 2, O 1, S 1, O - 2
- Cu+H 2 SO 4
- CuSO 4+H 2 O+SO 2
22. Balancing Equations
- Sulfur is not balanced.
- Place a two in front of sulfuric acid.
- Count atoms:2 H 2 SO 4 H 4, S 2, O - 8
- Cu+2 H 2 SO 4
- CuSO 4 +H 2 O+SO 2
23. Balancing Equations
- Hydrogen needs to be balanced so place a 2 in front of the H 2 O.
- Count the number of atoms.
- Cu+2 H 2 SO 4
- CuSO 4 +2 H 2 O+SO 2
24. Balancing Equations
- Reactants:Cu 1, H 4, S 2, O 8
- Products:Cu 1, S 1, O 4, H 4, O 2, S 1, O 2= Cu 1, S 2, H 4, O 8
- Its balanced!
- Cu+2 H 2 SO 4
- CuSO 4 +2 H 2 O+SO 2
25. Balancing Equations
- Balancing hints:
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- Balance the metals first.
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- Balance the ion groups next.
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- Balance the other atoms.
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- Save the non ion group oxygen and hydrogen until the end.
26. Balancing Equations
- This method of balancing equations is the inspection method.
- The method is trial and error.
- Practice.
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