# Colorimetric Estimation Method

Topics: Manganese, Concentration, Potassium permanganate Pages: 2 (441 words) Published: February 27, 2011
Using reducing agents I will reduce an acidified purple-pink solution of potassium permanganate to a colorless solution of manganese ions. Then I am going to record the time it takes for the loss of the color from the standardized solution and see if it is related to the fact that glucose is present. My hypothesis is that depending on how much glucose there is in a solution if it’s a low glucose solution in that solution then it has a longer time taken for it to dissolve but if it has a higher glucose solution in that certain solution then it will take a shorter time to dissolve.

Method
1.Using a plastic syringe, introduce 10cm cubed glucose solution and 5 cm cubed sulfuric acid into a flat-bottomed tube. Draw 2cm cubed potassium permanganate solution into a syringe, and press the stop-watch at the moment this addition is made to the contents of the tube. Record the time (secs) for complete decolorization. 2.Using the syringes, make dilutions of the glucose solution provided to obtain solutions containing 9, 8, 7, 6, 5, 4, 3, 2, and 1g glucose per 100 cm cubed distilled water. 3.Repeat procedure 1 with each glucose solution. Record all results in a table, and plot your result in graph form. 4.Use the graph to estimate the concentration of glucose in the unknown solutions.

Materials required
Standard solution: 10g glucose in 100 cm cubed water
Unknown solutions
Per group
15 flat –bottomed tubes
60 cm cubed glucose solution
30 cm cubed 0.01 M potassium permanganate solution
Timer
3*10cm cubed plastic syringes
60 cm cubed 1M sulfuric acid
150 cm cubed distilled water

Graph

The data that I have used does support the hypothesis, and the results have been put in order and labeled. You find that in my line graph the glucose percentage seems to go up in a non-straight line form and as soon as it reached near about 7:40 between 2% and 1% it rapidly decreases in minutes down to about 3:00. To me the reason why it went up so...