Rate of Reaction Flashcards
Collision Theory (2)
- For chemical reaction to occur, reactants must first collide with each other in the right orientation and w/ sufficient energy. (Activation energy, Ea)
- The higher the frequency of effective collisions between reactant particles, the faster the rate of reaction.
Define rate of rxn
The change in amnt of reactant/product per unit time.
Define catalyst
A substance that increases the rate of a chemical equation but remains chemically unchanged at the end of the reaction
How to measure rate of reaction (4)
- Measuring mass/volume changes (gas)
- Absorption using spectrometer (colour change)
- pH changes (acidity)
- Electrical conductivity (conc. of ions)
Factors affecting rate of rxn (5)
- Temperature
- Conc. of reactants
- Pressure of gaseous reactants
- Particle size
- Presence of catalysts/enzymes
Temperature (Proportionate, 2)
- Temp increases, more kinetic energy, move faster
- More particles possess energy equal to greater than Ea
Conc. of Reactants (Proportionate, 1)
- Conc increases, no. of particles per unit volume increases
Pressure of Gaseous Reactants (Proportionate, 2)
- Pressure increases, gas smaller volume, gas particles closer
- More reactant particles per unit volume
Particle Size of Reactants (Inverse, 1)
- Size decreases, surface area to volume ratio increases
Presence of Catalysts/Enzymes (Proportionate, 2)
- Catalyst used, provides alternate pathway w/ lower Ea
- More particles possess energy equal to or greater than Ea
Characteristics of Catalyst/Enzyme (5)
- Increased rate of rxn
- Only small amnt needed
- Provides alternate pathway w/ lower Ea
- Not used up during rxns (Chemically unchanged)
- Selective in action (Lock and key hypothesis)
Catalyst in Industries (4)
Iron - Manufacture of Ammonia
Platinum/Rhodium - Catalytic converters
Aluminium/Silicon Dioxide - Cracking process
Nickel - Adding of H2 to alkene to form alkane, conversion of vegetable oil to margarine
