what is the rate of reaction
change in conc / time
what is rate of reaction affected by
conc/ pressure of reactants
temperature
surface area
catalysts
how can you measure the rate of a reaction
by measuring an observable change
collect a volume of gas
measure the colour change/ change in pH
measure the loss of mass
when the solid becomes too small to see
what does increasing the conc do
increases rate
more frequent successful collisions
more particles will have energy greater than the activation energy
curve is same but higher
for example how would you find the order with respect to A
carry out multiple experiments
record a quantity at several intervals
plot a graph of volume vs time
draw a tangent to the curve at t=0
find gradient of tangent = initial rate
repeat with diff concs of A with other reactants in excess
Suggest why using a large excess of calcium carbonate means that the
rate is only affected by the changing concentration of the hydrochloric acid.
So that surface area/mass/amount stays (approx./effectively) constant
what does a 1st order rate concentration graph look like
straight line through the origin
what does a 2nd order rate conc graph look like
graph shows curve
increases with a steeper slope as conc increases
what does a 0 order rate conc graph look like
flat line
even though conc changes, rate remains constant
where do catalysts appear
in the rate equation not the chemical reaction
what does a 0 order conc vs time graph look like
straight line showing a constant decline in conc
gradient remains unchanged = rate is constant
gradient = rate constant
what does a 1st order conc vs time graph look like
slightly sloping curve with a constant half life (time taken for conc to halve)
gradient found by drawing tangent
