unit 3 Flashcards
what happens if the reaction rate is too low?
process will not be economically viable
what happens if the reaction rate is too high?
there will be an explosion
what is required for a successful collision?
energy above or equal to the activation energy
correct collision geometry
what forms when atoms have a successful collision?
an activated complex
what is an activated complex?
unstable arrangement of atoms
how does particle size increase the rate of reaction?
decrease particle size increases surface area
larger area for collisions to occur on
how does concentration increase the rate of reaction?
increase concentration
more particles moving around so more collisions occurring
how does temperature increase the rate of reaction?
increase temperature
particles have a higher level of energy
more particles have energy above or equal to the activation energy
how does pressure increase the rate of reaction?
pressure increases
particles are pushed together
how do catalysts increase the rate of reaction?
offers a different pathway with a lower activation energy
what is the activation energy?
minimum energy required by colliding particles to form an
activated complex
enthalpy change exothermic
pos/neg
negative
enthalpy change endothermic
pos/neg
positive
enthalpy representation in an equation
deltaH
why is the atom economy 100%?
only one product is formed
how are industrial processes designed?
to maximize products
to minimize environmental impact
factors influencing industrial design
sustainability
cost
recycle
energy
availability
marketability
yield
what is feedstock?
a reactant which goes into a chemical process, usually extracted from raw materials
what are raw materials?
natural resources the earth supplies us
what are environmental considerations?
minimising waste
avoiding the use or production of toxic substances
designing products which will biodegrade if possible
what is enthalpy?
a measure of the chemical energy in a substance
exothermic reactions in industry
releases heat energy
may require heat to be removed to prevent the temperature rising
endothermic reactions in industry
takes in heat energy
costs increased by supplying heat energy in order to maintain the reaction rate
what is the enthalpy of combustion?
one mole of the substance burns completely in oxygen
when changing the fuel, what variable are you keeping the same?
distance between flame and copper can
mass of water
windshields
thermometer positioning
why are your results lower than the EOC standard results?
heat lost to surroundings
incomplete combustion of alcohol
mass loss due to evaporation of alcohol
why are bomb calorimeter used?
no energy is lost as the vessel is sealed (all energy is transferred to the water)
it allows for complete combustion
what is bond enthalpy?
energy required to break one mole of bonds in a diatomic molecule
what is mean bond enthalpy?
average energy required to break one mole of bonds for a bond that occurs in a number of compounds
why is bond breaking positive?
energy has to be put in
- endothermic
rules for dynamic equilibrium
- rate of the forward reaction is equal to the rate of the reverse reaction
- the concentration of reactants and products remains constant
- the concentrations are not usually equal
- the reaction has not stopped
how does a reaction achieve equilibria
has to be a closed system
effect of a catalyst on equilibrium
no effect on the position of equilibrium
allow equilibrium to be reached more quickly or established at a lower temper (makes reactions more profitable)
what is chromotography?
technique used to separate the components present within a mixture
how does chromatography separate substances?
making use of differences in their polarity (solubility) or molecular size (smaller the molecule, the further they travel)
how can you identify a component through chromatography?
the distance it has travelled or the time it has taken to travel through the apparatus (retention time)
what is used to show the end point of a titration?
an indicator
what is a standard solution?
a solution of accurately known concentration
why does a redox titration using acidified permanganate does not require an indicator?
the solution turns colourless when reduced
what solution does not require an indicator during a redox titration?
acidified permanganate solution
process of making a standard solution
dissolve substance in water
transfer solution and rinsings to a volumetric flask
fill volumetric flask up to the line with water
describe process of using burette in a titration
rinse out burette with solution going in it
fill it to above the scale
drain some of the acid and read from the bottom of the meniscus
if an indicator is not clear enough, what do you use to show the end point in a titration?
white tile below conical flask
