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Chemical Equations. Describing Chemical Reactions. 5 Indications of a Chemical Reaction. Release of energy as heat. 5 Indications of a Chemical Reaction. Release of energy as heat Release of energy as light. 5 Indications of a Chemical Reaction. Release of energy as heat
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Chemical Equations Describing Chemical Reactions
5 Indications of a Chemical Reaction • Release of energy as heat
5 Indications of a Chemical Reaction • Release of energy as heat • Release of energy as light
5 Indications of a Chemical Reaction • Release of energy as heat • Release of energy as light • Production of a gas
5 Indications of a Chemical Reaction • Release of energy as heat • Release of energy as light • Production of a gas • Formation of a precipitate
5 Indications of a Chemical Reaction • Release of energy as heat • Release of energy as light • Production of a gas • Formation of a precipitate • Color change
Chemical Equations • Represent all reactants and products involved
Chemical Equations • Represent all reactants and products involved • Contain correct formulas (Note diatomic molecules) H2, N2, O2, F2, Cl2, Br2, I2, . . . also P4, S8
Chemical Equations • Represent all reactants and products involved • Contain correct formulas (Note diatomic molecules) H2, N2, O2, F2, Cl2, Br2, I2, . . . also P4, S8 • Must observe law of conservation of mass Same number of atoms on either side.
Chemical Equations • Represent all reactants and products involved • Contain correct formulas (Note diatomic molecules) H2, N2, O2, F2, Cl2, Br2, I2, . . . also P4, S8 • Must observe law of conservation of mass Same number of identical atoms on either side. Equations are “balanced” using coefficients, numbers that precede a formula. 2H2 + 02 2H2O
Chemical Equations • Represent all reactants and products involved • Contain correct formulas (Note diatomic molecules) H2, N2, O2, F2, Cl2, Br2, I2, . . . also P4, S8 • Must observe law of conservation of mass Same number of identical atoms on either side. Equations are “balanced” using coefficients, numbers that precede a formula. 2H2 + 02 2H2O
Balancing Chemical Equations • Start with unbalanced “formula equation” BF3 + Li2SO3 B2(SO3)3+ LiF
Balancing Chemical Equations • Start with unbalanced “formula equation” BF3 + Li2SO3 B2(SO3)3+ LiF • Balance different atoms one at a time.
Balancing Chemical Equations • Start with unbalanced “formula equation” BF3 + Li2SO3 B2(SO3)3+ LiF • Balance different atoms one at a time. • First balance atoms that are combined and appear only once on either side. BF3 + Li2SO3 B2(SO3)3+ 3LiF
Balancing Chemical Equations • Start with unbalanced “formula equation” BF3 + Li2SO3 B2(SO3)3+ LiF • Balance different atoms one at a time. • First balance atoms that are combined and appear only once on either side. BF3 + Li2SO3 B2(SO3)3+ 3LiF 2BF3 + 3Li2SO3 B2(SO3)3+ 6LiF
Balancing Chemical Equations • Start with unbalanced “formula equation” BF3 + Li2SO3 B2(SO3)3+ LiF • Balance different atoms one at a time. • First balance atoms that are combined and appear only once on either side. BF3 + Li2SO3 B2(SO3)3+ 3LiF 2BF3 + 3Li2SO3 B2(SO3)3+ 6LiF • Balance polyatomic ions that appear on both sides as single units.
Balancing Chemical Equations • Start with unbalanced “formula equation” BF3 + Li2SO3 B2(SO3)3+ LiF • Balance different atoms one at a time. • First balance atoms that are combined and appear only once on either side. BF3 + Li2SO3 B2(SO3)3+ 3LiF 2BF3 + 3Li2SO3 B2(SO3)3+ 6LiF • Balance polyatomic ions that appear on both sides as single units. • Balance H and O atoms last.