RP7: Measuring rate of reaction Flashcards
What is meant by ‘Rate of Reaction’?
The change in concentration of reactants or products over time.
How can rate of reaction be measured?
Initial rates method
continuous monitoring method
What is the initial rates method?
The iodine clock reaction
The method involves measuring the initial rate of reaction for multiple different concentrations to observe how rate of reaction varies.
What is the continuous monitoring method?
Measuring the volume of gas released in a reaction over time
What are the issues with this experiment?
- Some low I- concentrations may take too long to react
- Delayed stopwatch reactions
- Concentrations may not be exact due to measuring apparatus
What is the continuous monitoring method?
Measuring the change in concentration of a reactant or product over time (or measuring volume of gas released) as the reaction progresses
Give a continuous monitoring method.
- Add Magnesium Ribbon to Hydrochloric Acid
- Place bung in flask and start timer
- Note down the volume of hydrogen gas collected every 15 seconds for a period of 2.5 minutes
- Repeat for different HCl concentrations
How would you analyse the data from this experiment?
Plot a graph:
Y (Volume of Hydrogen Gas)
X (Time)
Rate of reaction = gradient of tangent
What should the set up for this experiment look like?
Conical flask with gas syringe
What are some issues with this experiment?
Some gas may escape before the bung is added
The magnesium strips may be of different mass and surface area which will affect the rate of reaction
How do you prevent gas escaping?
Place the solid reactant upright inside a sample tube in a conical flask, tipping the tube over by moving the conical flask around to start the reaction
