Chemical Reactions Flashcards
Requirements for reactions to occur (2)
must have correct collision geometry
must collide with sufficient energy
What happens to rate of reaction over time (2)
slows down until stops
time progresses –> concentration of reactant decreases –> decreases frequency of reaction
How can rate of a reaction be measured
how quickly reactant is used
how quickly product formed
How can rate of reactions that produce a gas be measured (2)
rate of loss in mass of reactants (mass balance)
rate of gas formation (gas syringe + displacement of water)
Gas Syringe rate of reaction diagram requirements (3)
syringe should have graduation marks
delivery tube must not be cut off
plunger should be slightly pushed out
Limitations of using a gas syringe to measure rate of reaction (3)
bung may not be securely fit –> gas might escape
delivery tube may not be securely fit –> gas might escape
if plunger is stiff –> gas pressure will increase
Displacement of water rate of reaction experiment requirements (3)
gases produced must be insoluble under water
graduation marks on measuring cylinder
delivery tube should not be cut off
Limitations of using displacement of water to measure rate of reaction (3)
bung may not be securely fit –> gases might escape
delivery tube may not be securely fit –> gas might escape
if gas is soluble in water not all gas is collected
Calculating the rate of reaction
measuring change in quantity over time interval
Factors that effect rate of reaction (4)
Concentration of reactants
Temperature
Particle Size/Surface Area
Catalyst
How concentration increases the rate of a reaction (2)
increased concentrations –> more particles to collide together + react
Relationship between concentration and rate of reaction
directly proportional
How temperature increases rate of a reaction (3)
increased temperature –> particles have more energy + move around faster –> greater chance of collisions + reaction happens quicker
How particle size/surface area increases rate of a reaction (2)
smaller particle size + greater surface area –> reaction surface area increased + more surface for collisions
Reducing particle size to increase rate of reaction in industry
catalytic converters - have honeycomb structure which increases surface area