Thanksgiving Gifts from Photosynthesis OR Nature’s Chemistry at It’s Best

Thanksgiving Gifts from Photosynthesis Have a great Thanksgiving holiday!

Section 8.2 Other Reactions in Aqueous Solutions Sections identify various types of chemical reactions 2.identify the processes and driving forces behind different types of reactions 3.Write equations for different types of reactions Learning Goals – I will be able to…

Section 8.2 Other Reactions in Aqueous Solutions Sections Formation of a Solid Precipitation, a Double Displacement Reaction (covered in 8.1) General equation: AB + CD  AD + CB Precipitation reaction Double displacement/replacement reaction

Section 8.2 Other Reactions in Aqueous Solutions Sections Formation of Water: Acids and Bases (not in notes): A different type of double replacement reaction A strong acid is one in which virtually every molecule dissociates (ionizes) in water to an H + ion and an anion.

Section 8.2 Other Reactions in Aqueous Solutions Sections A strong base is a metal hydroxide that is completely soluble in water, giving separate OH  ions and cations. Formation of Water: Acids and Bases (not in notes) –Most common  NaOH, KOH

Section 8.2 Other Reactions in Aqueous Solutions Sections Formation of Water: Acid-Base Reaction, a Double Replacement Reaction (not in notes) The products of the reaction of a strong acid and a strong base are water and a salt. Net ionic equation H + (aq) + OH − (aq)  H 2 O(l) Reaction of H + and OH − is called an acid-base reaction. H +  acidic ion OH −  basic ion The other anion/cation pair forms a Salt (Ionic compound) * NOTICE THAT IF THE PROPER AMOUNTS OF ACID AND BASE ARE MIXED THE PH OF THE SOLUTION WILL BECOME NEUTRAL. *

Section 8.2 Other Reactions in Aqueous Solutions Sections Acids and bases are both ionic compounds  strong acids/bases are strong electrolytes. Acids produce H+ ions in water. Bases produce OH- ions in water. Water is a very stable compound  strong tendency for reaction to happen. Acid + Base  Water + Salt HCl (aq) + NaOH (aq)  H 2 O (l) + NaCl (aq) Net Ionic Equation: H+(aq) + OH−(aq)  H 2 O(l) Formation of Water: Acid-Base Reaction, a Double Replacement Reaction (notes summary)

Section 8.2 Other Reactions in Aqueous Solutions Sections Transfer of Electrons -- Reactions of Metals with Nonmetals (Oxidation-Reduction) Reactions between metals and nonmetals involve a transfer of electrons from the metal to the nonmetal. Oxidation–reduction reaction (redox)

Section 8.2 Other Reactions in Aqueous Solutions Sections Transfer of Electrons: Oxidation-Reduction Reactions A metal and a nonmetal combine to form an ionic compound. Ex.: 2Na (s) + Cl 2(g)  2NaCl (s) Electron transfer: –sodium is “oxidized”  loses one electron –chlorine is “reduced”  gains one electron

Section 8.2 Other Reactions in Aqueous Solutions Sections Single Replacement – One Ion Replaced Driving force: –Transfer of electrons General equation: A + BC  B + AC

Section 8.2 Other Reactions in Aqueous Solutions Sections Single Replacement Reaction – One Ion Replaced (another example) Driving forces: –Transfer of electrons –Formation of a Gas

Section 8.2 Other Reactions in Aqueous Solutions Sections Involve oxygen & produce a flame (energy released rapidly) CH 4 (g) + 2O 2 (g)  CO 2 (g) + 2H 2 O(g) Combustion Reactions Types of Oxidation-Reduction Reactions (Redox) A compound forms from simpler materials C(s) + O 2 (g)  CO 2 (g) Synthesis (Combination) Reactions A compound is broken down into simpler substances 2H 2 O(l)  2H 2 (g) + O 2 (g) Decomposition Reactions Single Replacement (seen before) – new ion forms

Section 8.2 Other Reactions in Aqueous Solutions Sections Ways to Classify Reactions (notes summary) Precipitation – a solid forms Double Replacement (Displacement) – two ions exchanged/replaced Ex.: acid-base, precipitation Single Replacement – one ion replaced Combustion – energy is released, flame; oxygen is a reactant Synthesis – reactants combine to form product(s) Decomposition – reactant breaks down into products * Refer to reaction sheet to see examples. * *REDOX REACTIONS*