BALANCING CHEMICAL EQUATIONS Balancing Chemical Equations Rules 1
BALANCING CHEMICAL EQUATIONS. Balancing Chemical Equations
Rules: 1. The same number of atoms of each element appearing in reactants must appear in the products. 2. The subscripts of a formula cannot be changed to balance the equation. 3. Choose compound with greatest number of atoms first. 4. Balance by placing necessary coefficients in front of entire molecules. NO SUBSCRIPT CHANGES!
Rules cont. 5. Be certain each side of equation has same number of atoms of each type. 6. Make sure coefficients are in lowest whole number ratios. 7. Polyatomic ions usually stay intact, but multiple polyatomic ions may be separated. 8. (aq. ) stands for aqueous which is Latin for water solution: (g) gas (l) liquid (s) solid (c) crystalline solid
More Rules: means “yields” and shows direction of action ∆ above arrow shows heat has been added shows reaction is reversible MINHO: try Metals first, then Ions, then Nonmetals, and Hydrogen, then Oxygen last
Sample Problem: C 8 H 18 + O 2 CO 2 + H 2 O C 8 H 18 + O 2 __ CO 2 + __ H 2 O C 8 H 18 + __ O 2 __ CO 2 + __ H 2 O __ C 8 H 18 + __ O 2 __ CO 2 + __ H 2 O
Practice Problems: H 2 Cr. O 4 + Ag. NO 3 Ag 2 Cr. O 4 + HNO 3 (aq) (s) (aq) Chromic Acid 1, 2, 1, 2 + Silver + Nitric Nitrate Chromate Acid Double displacement
Problem # 6 Cu(NO 3)2 (aq) Cu. O + NO 2 + O 2 (s) (g) Copper (II) + Nitrogen + Oxygen Nitrate Oxide Dioxide Gas 2, 2, 4, 1 Decomposition
Problem # 14 Al. Br 3 + Cl 2 Al. Cl 3 + Br 2 (aq) (g) Aluminum + Chlorine Aluminum + Bromine Bromide Gas Chloride Gas 2, 3, 2, 3 Single Displacement
Problem # 2 P 4 + O 2 + H 2 O H 3 PO 4 (s) (g) (aq) Phosphorus + Oxygen + Water Phosphoric (free) gas acid 1, 5, 6, 4 Synthesis
Problem # 20 sodium permanganate + sulfuric acid sodium sulfate + manganese (VII) oxide + water Na. Mn. O 4 + H 2 SO 4 Na 2 SO 4 + Mn 2 O 7 + H 2 O (aq) (s) (l) 2, 1, 1 Double Displacement
Problem # 3 Th(NO 3)4 + K 3 PO 4 (aq) Th 3(PO 4)4 + KNO 3 (s) (aq) Thorium + Potassium Nitrate Phosphate Nitrate 3, 4, 1, 12 Double Displacement
Problem # 22 sulfur trioxide + nitric acid sulfuric acid + nitrogen (V) oxide SO 3 + HNO 3 H 2 SO 4 + N 2 O 5 (g) (aq) (g) 1, 2, 1, 1 Double Displacement
Problem # 7 NH 4 NO 3 + Ca(OH)2 Ca(NO 3)2 + NH 3 + H 2 O (aq) (g) (l) Ammonium + Calcium + Ammonia + water Nitrate Hydroxide Nitrate 2, 1, 1, 2, 2 Double Displacement
Missing Products sodium chloride + potassium iodide Na. Cl + KI ____ + _____ (aq) (? ) Does a reaction take place?
Balancing Wars Problem # 1 Cu. SO 4 + H 3 PO 4 _____ + ______ (aq) A) B) C) D) E) 3, 1, 2, 1 3, 1, 1, 3 2, 3, 3, 2, 1, 3 2, 3, 3, 1 ((D)) Copper (II) + Phosphoric Copper (II) + Sulfuric Sulfate Acid Phosphate Acid
Balancing Wars Problem # 2 Mg(OH)2 + H 3 PO 4 _____ + ______ (aq) A. B. C. D. E. 1, 1, 1, 1 3, 2, 1, 3 2, 3, 1, 6 2, 3, 1, 1 3, 2, 1, 6 ((E. )) Magnesium + Phosphoric Magnesium + Water Hydroxide Acid Phosphate
Balancing Wars Problem # 3 Cu. Cl 2 + Na 3 PO 4 _____ + ______ (aq) A. B. C. D. E. 1, 2, 1, 2 2, 3, 1, 6 2, 3, 1, 1 3, 2, 1, 6 1, 1, 1, 1 ((D)) Copper (II) + Sodium Chloride Phosphate Copper (II) + Sodium Phosphate Chloride
Balancing Wars Problem 4 Potassium + Nickel (II) _____ + ______ Permanganate Nitrate A. B. C. D. E. 2, 1, 3, 1 1, 2, 1, 3 1, 1, 1, 1 ((A)) KMn. O 4 + Ni(NO 3)2 KNO 3 + Ni(Mn. O 4)2
Balancing Wars Bonus Problem KMn. O 4 + Na 2 C 2 O 4 + H 2 SO 4 K 2 SO 4 + Na 2 SO 4 + Mn. SO 4 + CO 2 + H 2 O
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