1). 0.02 mol dm-3 Potassium Manganate2). 0.2 mol dm-3 Glucose3). 2 mol dm-3 Sulphuric Acid4). 50 cm3 Burette5). 250 cm3 Beaker6). Measuring Cylinder7). Thermometer (-10 to 110 oC)Hypothesis:By adding glucose to a solution of KMnO4 and H2SO4, the solution will turn colourless and it will take a specific time for the reaction to complete. By increasing the temperature, the time it takes (the rate) for the solution to completely change to colourless will be increased. Thus it can be said, that it is being hypothesized that an increase in temperature will cause an equal increase in the rate of the reaction.
1). Using a measuring cylinder, place 50 cm3 of sulphuric acid into a 250 cm3 beaker, add 50 cm3 of water using the same measuring cylinder, and then, from a burette, run in 5 cm3 of the potassium manganate (VII) solution. Heat the resulting mixture to about 55 oC, stirring gently while heating. Place a beaker containing the hot solution on a white tile or a piece of paper.
2). Noting the time, pour 20 cm3 of the glucose solution (using a measuring cylinder) into the beaker. Swirl and then measure the temperature. Note the time when the solution turns colourless.
4). Record the results in table as seen on the proceeding page.
5). Plot a graph of time against temperature (since temperature is the independent variable).
6). Analyze the graph after the values have been plotted. Comment on the line of best fit and other deductions that can be seen.
7). Plot a graph of concentration of KMnO4 against time and deduce whether the reaction is zero order, first order or second order. Take the concentration as 0.02 mol dm-3.
The temperature is changed.
The amount of glucose solution remains the same.
The volumes of Potassium Manganate, Water and Sulphuric acid remains the same.
Measured VariablesThe volumes of sulphuric acid, water and potassium manganate is measured.
The temperature of the solutions are measured.
The time is recorded.
ExpectedResults:The reaction should increase as the temperature is increased, thus the time it takes for it to become colourless will be less than the temperature before. It may be expected that the reaction will reach a point where it cant proceed faster. The curve of the graph will level off.
Discussion & ConclusionThe experiment investigates the effect of temperature on the rate of reaction of Potassium manganate (VII) and glucose solution. In its simplicity, the experiment relies on the fact that an increase in temperature affects the rate of the reaction. The experiment entails that the time it takes for the solution to become colourless, when the glucose solution is added, is affected by the temperature of the solution. It is assumed to be that with increase in temperature, there will be a corresponding increase in the rate of the reaction.
Limitations of the experiment includes but are not limited to: use of only one concentration of sulphuric acid and potassium manganate. Varying the concentration may have varying results. Consecutive timings arent taken.
Sources of errors; Random errors may predominate the experiment such as when the volumes of the reagents are measured (parallax). Human reaction time will also be prevalent when the times are taken. Preparation of the 0.2 M glucose solution, when ascertaining the mass from the scale (parallax) and also the scale may not be calibrated.
The order can be deduced to be a zero order reaction because only one concentration is used and as the time increases, the straight line will lengthen.
It can be concluded that the experiment allows to investigate the rate of temperature of the reaction between potassium manganate (VII) and glucose solution.