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BALANCING CHEMICAL EQUATIONS

BALANCING CHEMICAL EQUATIONS. Chapter 6.5 DAY 1 & 2. Word equations or formula (skeleton) equations need to be balanced. The number of atoms of one element on the reactant side of an equation must equal the number of atoms of that same element on the product side of an equation.

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BALANCING CHEMICAL EQUATIONS

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  1. BALANCING CHEMICAL EQUATIONS Chapter 6.5 DAY 1 & 2

  2. Word equations or formula (skeleton) equations need to be balanced. • The number of atoms of one element on the reactant side of an equation must equal the number of atoms of that same element on the product side of an equation.

  3. This law states: the total mass of atoms must be the same on both sides of an equation. • This means that the mass of the reactants equals the mass of the products. • In other words, atoms can be neither created or destroyed in a chemical change. LAW OF CONSERVATION OF MASS

  4. Using Black line 6.5a, we will review counting atoms before we learn the skill of balancing equations. How to count atoms review

  5. 1) The symbol of an element represents one atom of that element Example: Ca = 1 atom 2) A subscript is a number written at the lower right corner after the symbol of an element. If there is more than one atom of the element in the molecule, then a subscript is used to indicate the number of atoms. Example: N2 = 2 atoms

  6. 3) A subscript outside a bracket multiplies all the elements inside the brackets. Example: Ba3(PO4)2 Barium – 3 atoms Phosphorus – 2 atoms Oxygen – 8 atoms 4a) A coefficient is a number written in front of a chemical symbol and indicates the number of atoms of that element. Example: 3C = 3 carbons

  7. 4b) A coefficient is a number written in front of a chemical formula and indicates the number of molecules of that compound. 2H2O =Hydrogen 2 x 2 = 4 atoms, Oxygen 1 x 2 = 2 atoms NOTE: A coefficient multiplies the number of atoms of each element in the formula. 4Cu(NO3)2 = Copper 1 x 4 = 4 atoms, Nitrogen 1 x 2 x 4 = 8 atoms, Oxygen 3 x 2 x 4 = 24 atoms

  8. STEP 1 – Write the formula equation of the reaction. Example: CH4 + O2 CO2 + H2O LET’S BALANCE EQUATIONS

  9. STEP 2 – Count the number of atoms of each type on the reactants side and on the products side reactants products O – 2 O - 3 C – 1 C - 1 H – 4 H – 2

  10. Step 3Multiply each of the formulas by an appropriate coefficient to balance the numbers of atoms. CH4 + 2 O2 CO2 + 2 H2O Step 4Count atoms on each side to verify. reactants products O – 4 O - 4 C – 1 C - 1 H – 4 H – 4

  11. hydrogen and oxygen produce water H2 + O H2O PRACTICE

  12. Aluminum and Oxygen produce Aluminum Oxide • Al + O2 Al2O3 Practice

  13. Ethylene and Oxygen produces carbon dioxide and water • C2H4 + O2 CO2 + H20 Practice

  14. Carbon dioxide and hydrogen produces Methane and water • CO2 + H2 CH4 + H20 Practice

  15. PAGE 229 # 2, 3ade Practice worksheet BLM 6.5c Assignment Class Work

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