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Balancing Chemical Reactions. Steps to Success in Balancing Chemical equations. Figure out whose a reactant and whose a product Write the formulas for the reactants on the left side of the arrow (if more than one, separate them with a “+”)
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Steps to Success in Balancing Chemical equations • Figure out whose a reactant and whose a product • Write the formulas for the reactants on the left side of the arrow (if more than one, separate them with a “+”) • Write the formulas for the products on the right side of the arrow (if more than one, separate them with a “+”) • List all the atoms in the products and the reactants • Use coefficients in front of formulas to make the numbers of atoms in the reactants and products equal • Quiz yourself • Check your answers
Example 1: Magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas 1. Figure out whose a reactant and whose a product ReactantProduct Magnesium magnesium chloride Hydrochloric acid hydrogen 2. Write the formulas for the reactants on the left side of the arrow (if more than one, separate them with a “+”) Mg + HCl 3. Write the formulas for the products on the right side of the arrow (if more than one, separate them with a “+”) Mg + HCl MgCl2 + H2(g)* *hydrogen is diatomic
Mg + HCl Mg + 2 HCl MgCl2 + H2(g)* MgCl2 + H2(g)* Example 1 (cont):Magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas • 4. List all the atoms in the products and the reactants Mg 1 H 1 Cl 1 Mg 1 H 2 Cl 2 5. Use coefficients* in front of formulas to make the numbers of atoms in the reactants and products equal Mg 1 H 2 1 Cl 2 1 Mg 1 H 2 Cl 2 * The coefficient multiples all the atoms in the molecule that its in front of
BaCl2 + Na3PO4 NaCl + Ba3(PO4)2 Example 2: Barium chloride reacts with sodium phosphate to form sodium chloride and barium phosphate 1. Figure out whose a reactant and whose a product ReactantProduct Barium chloride sodium chloride Sodium phosphate barium phosphate 2. Write the formulas for the reactants on the left side of the arrow (if more than one, separate them with a “+”) BaCl2 + Na3PO4 3. Write the formulas for the products on the right side of the arrow (if more than one, separate them with a “+”)
BaCl2 + Na3PO4 3 BaCl2 + 2 Na3PO4 NaCl + Ba3(PO4)2 6 NaCl + Ba3(PO4)2 Example 2 (cont):Barium chloride reacts with sodium phosphate to form sodium chloride and barium phosphate • 4. List all the atoms in the products and the reactants Ba 1 Cl 2 Na 3 P 1 O 4 Ba 3 Cl 1 Nal 1 P 2 O 8 5. Use coefficients* in front of formulas to make the numbers of atoms in the reactants and products equal Ba 3 1 Cl 6 2 Na 6 3 P 2 1 O 8 4 Ba 3 Cl 6 1 Na 6 1 P 2 O 8 * The coefficient multiples all the atoms in the molecule that its in front of
NH3(g) + CO2(g) + H2O(g) (NH4)2CO3 Example 3: When heated, ammonium carbonate breaks down into gaseous ammonia, carbon dioxide and water vapor 1. Figure out whose a reactant and whose a product ReactantProduct Ammonium carbonate ammonia carbon dioxide water 2. Write the formulas for the reactants on the left side of the arrow (if more than one, separate them with a “+”) (NH4)2CO3 3. Write the formulas for the products on the right side of the arrow (if more than one, separate them with a “+”)
NH3(g) + CO2(g) + H2O(g) 2 NH3(g) + CO2(g) + H2O(g) (NH4)2CO3 (NH4)2CO3 Example 3 (cont):When heated, ammonium carbonate breaks down into gaseous ammonia, carbon dioxide and water vapor • 4. List all the atoms in the products and the reactants N 2 H 8 C 1 O 3 N 1 H 5 C 1 O 3 5. Use coefficients* in front of formulas to make the numbers of atoms in the reactants and products equal N 2 H 8 C 1 O 3 N 2 1 H 8 5 C 1 O 3 * The coefficient multiples all the atoms in the molecule that its in front of
C6H12O6 + O2(g) CO2(g) + H2O Example 4: In plants, carbon dioxide and water combine to form glucose and oxygen 1. Figure out whose a reactant and whose a product ReactantProduct Carbon dioxide glucose water oxygen 2. Write the formulas for the reactants on the left side of the arrow (if more than one, separate them with a “+”) CO2(g) + H2O 3. Write the formulas for the products on the right side of the arrow (if more than one, separate them with a “+”)
C6H12O6 + O2(g) C6H12O6 + 6 O2(g) CO2(g) + H2O 6 CO2(g) + 6 H2O Example 4 (cont):In plants, carbon dioxide and water combine to form glucose and oxygen • 4. List all the atoms in the products and the reactants C 1 H 2 O 3 C 6 H 12 O 8 5. Use coefficients* in front of formulas to make the numbers of atoms in the reactants and products equal C 6 1 H 12 2 O 18 3 C 6 H 12 O 16 8 * The coefficient multiples all the atoms in the molecule that its in front of
Your turn Balance the following equations: • Zinc and lead (II) nitrate react to form zinc (II) nitrate and lead. • Aluminum bromide and chlorine gas react to form aluminum chloride and bromine gas • A solution of silver (I) nitrate reacts with solid copper to form copper (II) nitrate and solid silver. • Calcium hydroxide and phosphoric acid react to form calcium phosphate and water. • Potassium metal reacts with chlorine gas to form potassium chloride. • Iron (III) oxide reacts with hydrogen gas to form solid iron and water.
the Answers • Zinc and lead (II) nitrate react to form zinc nitrate and lead. • Zn + Pb(NO3)2 Zn(NO3)2 + Pb already balanced • Aluminum bromide and chlorine gas react to form aluminum chloride and bromine gas • 2 AlBr3 + 3 Cl2 (g) 2 AlCl3 + 3 Br2 (g) • A solution of silver (I) nitrate reacts with solid copper to form copper (II) nitrate and solid silver. • 2 Ag(NO3) + Cu Cu(NO3)2 + 2Ag • Calcium hydroxide and phosphoric acid react to form calcium phosphate and water. • 3 Ca(OH)2 + 2 H3PO4 Ca3 (PO4)2 + 6 H2O • Potassium metal reacts with chlorine gas to form potassium chloride. • 2 K + Cl2 (g) 2 KCl • Iron (III) oxide reacts with hydrogen gas to form solid iron and water. • Fe2O3 + 3 H2(g) 2 Fe + 3 H2O