Flashcards in 18.3 rate-concentration graphs and initial rates Deck (13):
What does a 0 order rate-concentration graph look like?
A horizontal straight line, with a 0 gradient and the u-intercept =k
What does a first order rate-concentration graph look like?
A straight line through the origin, gradient = k, positive gradient
What does a second order rate-concentration graph look like?
An upward curve with increasing gradient, gradient = k an d the graph is plotted rate-con^2
How is the initial rate of a reaction calculated?
It is the instantaneous rate at the start of a reaction when time=0, it is found by measuring gradient at t=0 on a concentration- time graph
What is a clock reaction?
A convenient way of obtaining initial rate with a single measurement
How do you carry out a , iodine clock reaction?
Several experiments are carried out with different concentrations of one reactant with all other reactant concentrations staying constant
How can the colour change of an iodine clock reaction be delayed?
By adding a small amount of another chemical such as Na2S2O3, which removes iodine as it forms
What will the colour change be in an iodine clock reaction?
Colourless to blue/black if starch is present or organge/brown if not
What measurements do you take in an iodine clock reaction?
You measure the time taken for the colour change to take place
In an iodine clock reaction, what is initial rate proportional to?
1/t (provided there was no significant change in reaction between t=0 and colour change)
In an iodine clock reaction, what graph is plotted?
1/t against concentration
How can order be determined from an iodine clock reaction?
Carry out lots of reactions changing the concentrations of other reactants