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Chemical Reactions Ch 10. Chemical Reactions. A + B => AB reactants (R) => products(P). Chemical Reactions. Evidence of Chemical reaction: A) bubbles form (g) B) precipitate forms (s) C) odor D) color change E) energy change. Chemical reactions.
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Chemical Reactions • A + B => AB • reactants (R) => products(P)
Chemical Reactions • Evidence of Chemical reaction: • A) bubbles form (g) • B) precipitate forms (s) • C) odor • D) color change • E) energy change
Chemical reactions • Symbols for states of matter: • “s” -----solid • “cr”------crystals • “g” -----gas • “l” -----liquid • “aq”------ions in H2O
Chemical reactions • => yields or produces • reversible reactions • + react with or “and”
Chemical Reactions • Subscripts---indicate the # of at in a formula ( never change subscripts to balance an eq) • Coefficients—large # in front of formula that indicates the # of moles reacting. Use coefficients to balance eq
Chemical Reactions • Due to Law of Conservation of Mass, the chem eq must be “balanced”. “P” must = “R” in mass and in # of atoms • Chemical sentence: • Two moles of potassium chlorate decompose to produce 2 moles of potassium chloride and 3 moles of oxygen gas • 2KClO3 => 2KCl + 3 O2
Chemical Reactions • REMEMBER THE DIATOMIC MOLECULES: use when these elements occur “alone” in reaction. • --- O2 • -----N2 • ------H2 • ------F2 • -----Cl2 • -----Br2 -------I2
Solutions • Aqueous solution—a solution in which the solvent is H2O • HCl (aq) => H+(aq) + Cl-(aq) • When HCl is added to H2O it forms ions of H+ & Cl-
Reaction types • Types of Reactions: • A) synthesis: 2 or more substances combine to form 1 new substance • ele + ele => comp • 2 Na + S => Na2S • ele + comp => comp • O2 + 2SO2 => 2SO3
Reaction Types • 2. Single replacement: 1 ele replaces another ele in a comp. • Remember: metal replaces metal and non-metal replaces non-metal • Ele + Comp => comp + ele • K + NaCl => KCl + Na or Cl2 + MgBr2 => MgCl2 + Br2
Replacement Series • On page 281 of text find the replacement series. • An ele can replace any ele below it in the chart • Ex: Li metal can replace any other metal in a comp • F2 replace any other halogen from a comp • F • Cl • Br • I
Reaction Types • 3.Double Replacement: • The “+” and “-” portions of 2 comp are interchanged • Compound + compound => compound + compound • NaOH + HCl => NaCl + HOH • Silver nitrate reacts with sulfuric acid to produce silver sulfate and nitric acid
Neutralization Reaction: A double replacement reaction between acid and base. • Products are ALWAYS water and a salt • HNO3 + Ca(OH)2 => HOH + Ca(NO3)2 Balance the equation
Reaction Types • 4. Combustion: Reaction of a hydrocarbon and oxygen to produce water and carbon dioxide ( Heat is released ) ( exothermic) • CnH2n+2 + O2 => H2O + CO2
Reaction Types • 5. Nuclear Reactions: • 210Po => 206Pb + 4He • 84 82 2
Reaction Types • 6. Decomposition: breaking up of substances into simpler substances when energy is supplied. • Comp => ele + ele • Comp => ele + comp
Reaction types • Types of decomposition: • A) simple • binary comp => ele + ele • 2 NaCl => 2 Na + Cl2 • B) metallic carbonate decomposition • MCO3 => MO + CO2 • C) metallic hydroxide decomposition • MOH => MO + H2O • D) metallic chlorate decomposition • MClO3 => MCl + O2
Balancing Equations • 1.Write the skeleton eq for reaction • H2(g) + Cl2(g) => HCl (g) • 2. Count the at of the ele in the “R” • 3. Count the at of the ele in the “P” • 4. Change the coefficients to make the # of at of each ele = on both sides of eq • 5. Write the coefficients in the lowest ratio
Balancing Equations • Page 290 have charts with guidelines for balancing; • double-replacement reactions
Write, balance and classify the following: • 1. water and magnesium acetate forms when acetic acid reacts with magnesium hydroxide. • 2. Aluminum hydroxide reacts with silver nitrate to form silver hydroxide and aluminum nitrate.