Required Practicals

Question 1

Monitoring the production of gas using a gas collection (Rates of Reaction)

Answer 1

• 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.

Question 2

Monitoring loss of mass of reactants using balance (Rtes of Reaction.)

Answer 2

• 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.

Question 3

Monitoring by Colorimetry (Rate of Reaction)

Answer 3

• 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.

Question 4

Rates of Reaction (Initial rates method )

Answer 4

• 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.