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Chemical equation the symbolic representation of a chemical reaction (process) wherein the reactant entities are on left side and change into product entities on right-hand side. Chemical Equation Symbols The arrow can be read as “yields” or “produces”
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Chemical equation the symbolic representation of a chemical reaction (process) wherein the reactant entities are on left side and change into product entities on right-hand side
Chemical EquationSymbols The arrow can be read as “yields” or “produces” The + sign reads as “and” or “plus”
Chemical EquationSymbols The arrow can be read as “yields” or “produces” Coefficients are the numbers in front of the formulas Coefficients can be changed to balance chemical equations Subscripts tell us how many atoms or molecules we have NEVER change subscripts when balancing chem. equations
Br2 + Al Al2Br6 (not balanced) Balance using coefficients Balancing Equations like solving a puzzle
Balancing Equations Reactants Products O2 + H2 H2O
Balancing Equations Reactants Products O2 + H2 H2O but this equation is not balanced why not?
Conservation of Mass- Mass and/or Atoms are not Created or Destroyed during a chemical reaction. There must be the Same number of atoms on each side of the equation to balance the chemical equation. Balancing Equations
Steps to Balance Chemical Equations 1. Write unbalanced equation. 2. Count # atoms on each side. 3. Add coefficients to make #s of atoms equal. Coefficient subscript = # of atoms 4. If necessary reduce coefficients to lowest possible ratio (never change subscripts) • Update and Double check atom balance!!!
Balancing Equations Step 1. Write unbalanced equation O2 + H2 H2O
Balancing Equations Step 2. Count # of atoms on each side O2 + H2 H2O O = 2 0 = 1 H = 2 H = 2
Balancing Equations 3. Add coefficients to make # of atoms = on each side O2 + H2 H2O O = 2 0 = 1 H = 2 H = 2
Balancing Equations 3. Add coefficients to make # of atoms = on each side O2 + 2 H2 2 H2O O = 2 0 = 2 H = 4 H = 4
Balancing Equations 4. If necessary find lowest ratio (never change subscripts) O2 + 2 H2 2 H2O O = 2 0 = 2 H = 4 H = 4
Balancing Equations 5. Update and double check work O2 + 2 H2 2 H2O O = 2 0 = 2 H = 4 H = 4
Balancing Steps 1. Write the unbalanced equation. Al + CuCl2 Cu + AlCl3
Balancing Steps 1. Write the unbalanced equation. 2. Count atoms on each side. Al + CuCl2 Cu + AlCl3 1 Al 1 1 Cu 1 2 Cl 3
Balancing Steps 1. Write the unbalanced equation. 2. Count atoms on each side. 3. Add coefficients to make #s equal. Coefficient subscript = # of atoms Al + CuCl2 Cu + AlCl3 1 Al 1 1 Cu 1 2 Cl 3
Balancing Steps 1. Write the unbalanced equation. 2. Count atoms on each side. 3. Add coefficients to make #s equal. Coefficient subscript = # of atoms Al + 3 CuCl2 Cu + 2 AlCl3 1 Al 2 3 Cu 1 6 Cl 6
Balancing Steps 1. Write the unbalanced equation. 2. Count atoms on each side. 3. Add coefficients to make #s equal. Coefficient subscript = # of atoms 2 Al + 3 CuCl2 3 Cu + 2 AlCl3 2 Al 2 3 Cu 3 6 Cl 6
Balancing Steps 1. Write the unbalanced equation. 2. Count atoms on each side. 3. Add coefficients to make #s equal. Coefficient subscript = # of atoms 4. Reduce coefficients to lowest possible ratio, if necessary. 5. Double check atom balance!!!
Helpful Tips • Balance one element at a time. Balance most complicated compound first! • Update ALL atom counts after adding a coefficient. • Balance (polyatomic ions) as (single units). • “1 SO4” instead of “1 S” and “4 O” • Balance most complicated compound first, balance oxygen and hydrogen last (MINOH metals, ions, non-metals, oxygen, hydrogen) • Ask yourself this question what am I forced to do to balance the equation???
Examples ____ Mg + ____ O2 ____ MgO
Examples 2 Mg + O2 2 MgO
Examples ____ Al + ____ S ____ Al2S3
Examples 2 Al + 3 S Al2S3 ____ C3H8 +____ O2 ____ CO2 + ____ H2O
Examples 2 Al + 3 S Al2S3 C3H8 + 5 O2 3 CO2 + 4 H2O
More Examples ___ Al +____ H2SO4 ____Al2(SO4)3 +____ H2
More Examples 2 Al + 3 H2SO4 Al2(SO4)3 + 3 H2
Helpful Tips • Balance one element at a time. • Update ALL atom counts after adding a coefficient. • Balance (polyatomic ions) as (single units). • “1 SO4” instead of “1 S” and “4 O” • Balance most complicated compound first, balance oxygen and hydrogen last • Ask yourself this question what am I forced to do to balance the equation???
Steps to Predicting Products • Determine Reaction Type • Predict Product Formulas • Verify subscripts on Product Formulas • Final Step Balance Equation
Determine Reaction Type • Predict Product Formulas • Verify subscripts on Product Formulas • Final Step Balance Equation Ag + Cu(SO4)
Determine Reaction Type • Predict Product Formulas • Verify subscripts on Product Formulas • Final Step Balance Equation Ag + Cu(SO4)