RATE AND HEAT OF REACTIONS + REVERSIBLE REACTIONS
RATE OF REACTION
Fast-explosions, slow-baking cakes, formation of oil + coal
Depends on particles colliding and having enough energy (break bonds/ forces of attraction)

Concentration (solutions)
-high conc. faster > more collisions
Pressure(gas) [low pressure > lower b.p.]
-high pressure faster > less space > more collisions
Particle Size(solids)
-larger SA, faster > more area to collide
Temperature(increase in 100°C, 2x reaction rate)
-high temp, faster, more speed > more collisions, more energy > break bonds/ forces of attraction
Catalysts
-chemical that speed up (or slow down) reactions, not used up in reaction, remain unchanged, reaction requires less energy


Measuring Speeds of Reaction
-measure vol. of gas produced or escaping
-measure mass of reactant and products
-measure time taken for cross to disappear (ppt.)




HEAT OF REACTION
There is a given amount of energy (enthalpy) in reactants (H_r) and products (H_p)
Change in energy (kJ) = H_p - H_r or ΔH
Energy taken in- endothermic or given out- exothermic

EXOTHERMIC
Enthalpy- lost/ given out > temp. increase
Reactants more enthalpy
ΔH:-tive


ENDOTHERMIC
Enthalpy- gained/ taken in > temp. decrease
Products more enthalpy
ΔH:+tive


Bond breaking-uses energy, products more energy > endothermic
Bond forming-loses energy, reactants more energy > exothermic

Photosynthesis- endothermic- light used to make food (carbohydrates), 6CO₂ + 6H₂O + light > C₆H₁₂O₆ + 6O₂
Photography- endothermic- light abosrbed by Ag+ ions to make silver (dark areas on film) 2AgCl + light > 2Ag + Cl₂
Fuels- exothermic- burning of fuels, wood, coal, oil, gas, petrol, etc, from wood and plant materials, 2C₈H₁₈(petrol)+ 25O₂ > 18H₂O + 16CO₂ + E
Hydrogen- exothermic- rocket fuels, liquid H₂ & O₂ mixed burnt: 2H₂ + O₂ > 2H₂O + E
Nucluer Energy- exothermic- produces large amount of energy, heat H₂O > steam > elec. Energy, waste products > pollution
Batteries (Electric cells)- exothermic- 2 dif. metals in an electrolyte generate elec. chem. energy > elec. energy, more reactive metal > ions > e^- move to less reactive metal > elec. (further metals apart in reactivity series > larger voltage)


REVERSIBLE REACTIONS
NaCl (s) → Na⁺ (aq) + Cl^-(aq)
Na⁺ (aq) + Cl^-(aq) → NaCl (s)
NaCl (s) ↔ Na⁺ (aq) + Cl^-(aq)
→ forward reaction, ← reverse reaction, ↔ reversible reaction
reversible reaction = a reaction where there is a forward and reverse reaction
equilibrium-constancy of macroscopic properties in a closed system: when speed of forward reaction = speed of reverse reaction > conc of products and reactants, constant, requires a closed system so chemicals can't enter or escape which will lead to change in equilibrium

CONCENTRATION: reactants conc increased > forward reaction favoured
PRESSURE(gases): side w/ more # of moles more affected
TEMPERATURE: side w/ energy more affected
PARTICLE SIZE: no effect on equilibrium, only speeds up to equilibrium
CATALYSTS: no effect on equilibrium, only speeds up to equilibrium

The Periodic Table
Metals
Organic Chemistry
Non-metals
The Particulature Nature of Matter
Experimental Techniques
Atoms, Elements and Compounds
Stoichiometry + Mole Concept
Acids, Bases and Salts
Chemical Reactions + Electrolysis

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