RP7- Order of Reaction Flashcards
What is the initial rates method, used to find our rates of reactions?
measuring the initial rate for multiple concentrations to observe how this varies
What is the continuous monitoring method?
measuring the change in concentration of a reactant/product over time
Why is a large excess of other reactants used when investigating how the rate changes depending on the concentration of one specified reactant?
- concentration of other reactants is constant/change is negligible
- so has no effect on the rate
What must be done to any samples removed from the reaction mixture, before their concentration is determined?
- cooled
- to stop/quench the reaction
What is important when drawing a graph?
- axis labelled
- suitable scale
- line of best fit
- points plotted correctly
- data covers half the area of the graph
How can a graph be used to find the initial rate of reaction?
- carry out reaction
- monitor concentrations at timed intervals
- plot graph of conc vs t
- draw tangent at t = 0
- gradient of tangent
What reactants are used for the ‘iodine clock’ reaction?
- sodium thiosulfate (5cm3)
- potassium iodide (5cm3)
- a few drops starch
- water (20cm3)
- sulfuric acid (25cm3)
- hydrogen peroxide (10cm3)
What is the last reagent added before stop clock started?
hydrogen peroxide
Outline a continuous monitoring method for this practical…
- add HCl (50cm3) to a flask
- set up gas syringe ready
- add strip of Mg to the HCl and quickly place the bung on top
- record volume of gas every 10 seconds for 3 minutes
- repeat with different [HCl]
