DAILY QUESTION

October 29, 20081. What is the general form

for synthesis reactions?

Agenda 10/29/08

• Daily Question • Ch 6 Sect 2 Notes• Lab Safety Review

Assignments: 1. Ch 6 Sect 1 and Sect 2 Review Worksheets due

10/312. Extra Credit Crossword Puzzle

due Today!

Synthesis Reactions

A + B → AB• Always join substances to form a new,

more complex compound– Water:

H + O2 → H2O– Table salt:

2Na + Cl2 → 2NaCl– Photosynthesis:

6CO2 + 6H2O → C6H12O6 + 6O2

Decomposition Reactions

AB → A + B• Substances are broken down

– Electrolysis of water:

2H2O → 2H2 + O2

– Digestion– “Cracking” oil

Combustion Reactions

• Use oxygen as a reactant– Water is a common source of oxygen

• Products depend on the amount of oxygen available– Carbon dioxide– Carbon monoxide– Carbon

Single-displacement Reactions

AX + B → BX + A• A more reactive element will take the

place of a less reactive one– Copper(II) chloride and aluminum

3CuCl2 + 2Al → 2AlCl3 + 3Cu

• Alkali metals react with water to form ions– Potassium and water

K + H2O → KOH + H2

Double-displacement Reactions

AX + BY → AY + BX• Two compounds appear to exchange

positive ions– Formation of lead chromate:

Pb(NO3)2 + K2CrO4 → PbCrO4 + 2KNO3

Oxidation-Reduction Reactions

Reactions where electrons are transferred.

• Substances that accept electrons are:– Reduced

• Substances that give up electrons are:– Oxidized

In all redox reactions, one reactant is reduced and one is oxidized. They are linked.– Example: Formation of rust

OIL RIG

Oxidation Is Loss of electrons

Reduction Is Gain of electrons

Redox Reactions with Oxygen

Don’t have to be with ions… can be oxygen

• Oxidation: gain of oxygen or loss of hydrogen

• Reduction: loss of oxygen or gain of hydrogen

– Respiration– Combustion

Radicals

• When a covalent bond is broken and at least one unpaired electron is left on each fragment of the molecule

• React quickly to form covalent bonds with other substances, making new compounds