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Chapter 8:. CHEMICAL EQUATIONS AND REACTIONS. Indications of a Rxn. Heat or light given off Bubbling/smoke, gas being released Precipitate (solid) forms Change in the odor/color Chemical indicators turn color. Eqn Writing. Make sure you have the correct formula for each substance
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Chapter 8: CHEMICAL EQUATIONS AND REACTIONS
Indications of a Rxn • Heat or light given off • Bubbling/smoke, gas being released • Precipitate (solid) forms • Change in the odor/color • Chemical indicators turn color
Eqn Writing Make sure you have the correct formula for each substance Diatomic elements – exist only in pairs, always written with a 2 subscript H2 O2 N2 Cl2 Br2 I2 F2
Rxn/Eqn Parts H2 (g) + Cl2 (g) 2 HCl (g) Reactants Product (Reagents)
Law of Conservation of Matter Atom values must match on both sides Balance an eqn with coefficient multipliers ___H2 + ___O2 ____ H2O 2 1 2
___Al2O3 ___ Al + __O2 2 4 3 1 3 3 1 __Fe(NO3)3 + __KSCN __KNO3 + __Fe(SCN)3
Decomposition (analysis) One Reactantbreaking down into two or more products
Combustion • One or more reactants combine with oxygen, O2 , must invole heat or light Usually takes place with carbon compounds and produces carbon dioxide and water CH4 + O2 CO2 + H2O
Single Replacement (Displacement) • One element replaces a similar element in a compound
Double Replacement • the interchanging of two ions from two different compounds. • Products usually have a precipitate
Reaction rates The rate of disappearance of the reactants (concentration per second) Depends on activation energy and molecule collisions
Factors affecting rate: • Type of reactants ion exchange happens quick covalent bond rearrangement is slow 2) Concentration and pressure higher amount increases the collision rate.
3) Temperature – increase it and collision rate increases 4) Catalysts – increases the rate by lowering activation energy 5) Inhibitors – used to slow rate, preservatives.