1
Q
Monitoring the production of gas using a gas collection (Rates of Reaction)
A
- Apparatus: stopper, conical flask, water tub, 250cm3 measuring cylinder.
- Hydrogen peroxide added to conical flask and bung replaced.
- Initial vol gas in measuring cylinder recorded.
- Magnesium dioxide catalyst quickly added to conical flask and bung replaced
- vol of gas produced in measuring cylinder recorded at regular intervals until reaction complete.
- Complete when no more gas produced.
- graph of total vol of gas against time produced.
2
Q
Monitoring loss of mass of reactants using balance (Rtes of Reaction.)
A
- Add carbonate and acid to conical flask on balance.
- Mass of reagents and flask recorded initially and at regular intervals.
- Reaction complete when no more gas produced so no more lost.
- plot graph of mass lost against time.
3
Q
Monitoring by Colorimetry (Rate of Reaction)
A
- Select filter of complementary colour to coloured chemical.
- zero colorimeter with water.
- Measure absorbance of chemical.
- Plot calibration curve of absorbance against conc.
- Carry out reaction, take absorbance readings of the reacting mixture at measured time intervals.
- use calibration curve measure conc at each absorbance reading.
- Plot 2nd graph of conc against time.
4
Q
Rates of Reaction (Initial rates method )
A
- clock reaction convienient way to determine inital rate reaction as involves taking single measurement. (Measurement is time taken for visible change to occur.)
- if no sig change in rate during time, assume average rate of reaction over time is same as the intial rate.
- Initial rates is proportional to 1/t
- clock reaction repeated several times with diff concs.
- Iodine clock common type of clock reaction and relies of formation of iodine.
- from results, the order of reactants and rate equation can be written.
