Estimating glucose concentration in solution

How do the different glucose concentration in unknown solution which labelled A,B,and C are determined from the time taken for the loss of colour from a standardised solution of permanganate based on the different glucose concentration in known solution which are 5%, 10%, 15%, 20%, 25%, and 30% under the constant factors of volume of sulphuric acid, volume of potassium permanganate, and volume of glucose? Variables:

Units| Range| INDEPENDENT VARIABLE| Different concentration of glucose in solution| %| 5%, 10%, 15%, 20%, 25%, 30%, and A, B, C| DEPENDENT VARIABLE| Time taken for the loss of colour from a standardised solution of permanganate| s| Will be determined in the experiment|

No.| CONTROLLED VARIABLES| Units| Possible effect(s) on result| 1| Volume of sulphuric acid| cm3| Affect the no. of hydrogen ions (H+) produced for the reaction| 2| Volume of potassium permanganate| cm3| Affect the time taken for the loss of the colour| 3| Volume of glucose solution| cm3| The time taken will not be uniformly in sequenced order based on the concentration|

Hypothesis: Higher concentration of glucose in solution will shorten the time taken for the loss of colour from a standardised solution of permanganate. Glucose with higher concentration will transfer higher number of electron, thus fasten the reaction on producing manganese ions (Mn2+) and water (H2O). Hence, the colour will changes from pink to colourless in shorter time.

Method For Controlling Variables: No.| CONTROLLED VARIABLES| Method to control| 1| Volume of sulphuric acid| Fix the volume of sulphuric acid at 5cm3 for every test | 2| Volume of potassium permanganate| Fix the volume of potassium permanganate at 2cm3 for every test| 3| Volume of glucose solution| Fix the volume of each glucose solution at 10cm3 for every test|

Method For Collecting Data: 1. 3 beakers and 3 syringes were labelled: S – for Sulphuric Acid PP – for Potassium Permanganate G – for Glucose

2. 25cm3 of sulphuric acid and potassium permanganate were added into the beakers – this will be the stock to use throughout the experiment. Glucose solution which tested first was noted.

3. Correct syringe was used to place 10cm3 of the first glucose solution into the boiling tube.

4. 5cm3 of sulphuric acid was added.

5. 2cm3 of potassium permanganate was added. The clock was started immediately.

6. The solution was stirred using glass rod and the time taken was stopped as soon as the pink colour changed into colourless.

7. The time taken and the glucose solution used were recorded.

8. The syringe used for the glucose solution was rinsed.

9. Step 3 – 8 were repeated using the other glucose solution of known concentration.

10. Step 3 – 8 were repeated using the solution of unknown solution (A,B, or C)

11. The results were recorded and presented in a Standart Curve.

DATA COLLECTION AND PROCESSING

ASPECT 1 : DATA COLLECTION Table 1 : Recording Quantitative Raw Data of Known Solution Glucose concentration in solution| Time taken for the loss of colour of potassium permanganate,t (s) ±0.01s| | Group 1| Group 2| Group 3| Group 4| Group 5| Group 6| 5%| 241| 348| 315| 345| 265| 363|

10%| 125| 220| 71| 147| 141| 92| 15%| 47| 65| 50| 90| 88| 75| 20%| 40| 125| 37| 83| 42| 53| 25%| 37| 85| 35| 35| 39| 45| 30%| 27| 42| 32| 30| 29| 39| *My data group was in Group 4

Table 2: Recording Quantitative Raw Data of Unknown Solution Glucose concentration in solution| Time taken for the loss of colour of potassium permanganate,t (s) ±0.01s| | Group 1| Group 2| Group 3| Group 4| Group 5| Group 6| Boiling tube A| 118 | 240 | 139 | 108 | 121 | 184 | Boiling tube B| 1260 | 900 | 1248 | 1200 | 1952 | 1140 | Boiling tube C| 105 | 530 | 80 | 23 | 42 | 205 |

*My data group was in Group 4

Table 3 : Recording Qualitative Raw Data Process| Observations| Measuring time taken for the loss of colour of potassium permanganate in known solution| * Initial colour of the glucose solution was pale white.

* The colour changed from pale white to pink when it was added by potassium permanganate. * The end point of the time taken was determined when the colour of the solution turned into colourless (the boiling tube was shaken well)| Measuring time taken for the loss of colour of potassium permanganate in uknown solution|

* For boiling tube A and B, the observations were the same as the known solution. * For boiling tube C, the initial colour of glucose solution was dark brown. * The colour changed from dark brown to light brown when it was added by potassium permanganate. * The end point of the time taken was determined when the colour of the solution turned back into dark brown (the boiling tube was shaken well)| ASPECT 2 : DATA PROCESSING

From Table 1, 1. Calculating mean, (x) and standard deviation, (Sx) of the time taken for the loss of colour of potassium permanganate (s) ±0.01s Using G.D.C. (TI-84 Plus): 1. Press STAT 2. Bring your cursor to EDIT, then press 1 3. Bring your cursor to L1 4. Fill you data in the table, and press ENTER after each data inserted 5. Press STAT 6. Bring your cursor to CALC, then press 1 7. Press 2ND and 1, then press ENTER 8. x indicates mean while Sx indicates standart deviation Eg.: - Boiling tube with 5% of glucose concentration - x= 312.83 - Sx= 49.48

2. Plotting a graph of standard curve from the class average results, which was necessary as a standard guideline to estimate glucose concentration in the unknown solution.

Using Microsoft Office Excel 2007

1. In column A, insert the range of data of independent variables. (eg. : 5%, 10%, 15%, 20%, 25%, 30%) 2. In column B, insert the mean data of dependent variables. (eg. : ) 3. Highlight both column A and B. 4. Click at the INSERT icon, then click at SCATTER, and choose SCATTER WITH SMOOTH LINES. 5. The Standard Curve will be formed on the screen.

3. Estimating the glucose concentration in unknown solution using standard curve above. Eg.: - Boiling tube A * Mean = 151.67 * Standard deviation = 50.97 The data collected is compared to the Standard Curve, then we can estimate the glucose concentration of the boiling tube A. ASPECT 3 : DATA PRESENTATION

Table 4 : Presenting Quantitative Data of Known Solution (Standard Curve) Glucose concentration in solution| Time taken for the loss of colour of potassium permanganate (s) ±0.01s| Mean (x)| Standard deviation (Sx)| | Group 1| Group 2| Group 3| Group 4| Group 5| Group 6| | | 5%| 241| 348| 315| 345| 265| 363| 312.83| ± 49.48| 10%| 125| 220| 71| 147| 141| 92| 132.67| ± 51.80| 15%| 47| 65| 50| 90| 88| 75| 69.17| ± 18.83|

20%| 40| 125| 37| 83| 42| 53| 63.33| ± 34.61| 25%| 37| 85| 35| 35| 39| 45| 46.00| ± 19.46| 30%| 27| 42| 32| 30| 29| 39| 33.17| ± 5.98|

Graph 1: Standard Curve

Table 5 : Presenting Quantitative Data of Unknown Solution Glucose concentration in solution| Time taken for the loss of colour of potassium permanganate (s) ±0.01s| Mean(x)| Standard deviation(Sx)| Estimation of glucose concentra-tion| | Group 1| Group 2| Group 3| Group 4| Group 5| Group 6| | | | Boiling tube A| 118 | 240 | 139 | 108| 121| 184| 151.67| ± 50.97| 13.0%| Boiling tube B| 1260 | 900 | 1248 | 1200| 1952| 1140| 1283.33| ± 353.08| 0.0%| Boiling tube C| 105 | 530 | 80 | 23| 42| 205| 164.17| ± 190.23| 11.7%|

CONCLUSION AND EVALUATION

ASPECT 1 : CONCLUSION Higher concentration of glucose in solution will shorten the time taken for the loss of colour from a standardised solution of permanganate. Glucose with higher concentration will transfer higher number of electron, thus fasten the reaction on producing manganese ions (Mn2+) and water (H2O). Hence, the colour will changes from pink to colourless in shorter time. Hypothesis is accepted. Glucose concentration for A is 13%, B is 0%, and C is 11.7%.

ASPECT 2 : PROCEDURE EVALUATION Table 6: Evaluation Error| Problem| Way to overcome| Random error| When the syringe is rinsed with water, tiny water droplets are lefted in the syringe, thus affecting the concentration of glucose| Make sure the syringe is dried with small towel.| | Determine the starting point in taking time for the reaction| Time is started to be taken immediately after potassium permanganate is put in the boiling tube.| | Parallax error happens because the calibration of syringe is too small|

Measure the meniscus of the liquid solution with the exact level our eyes| Systematic error| The electronic balance was not been properly zeroed, thus causing zero error| Make sure that the electronic balance has been set with correct calibration / re-zero the instrument| | Determine the end point of reaction by colour changes| The end point time reading is taken immediately after the colour was completely changed.| | Rate of stirrings are different for every person| |

Referrences: 1. Unit: Cell and Molecular Biology (AH): Structure and Function of cell components i) Carbohydrates – structure of monomer glucose. Title: Estimating glucose concentration in solution, BACKGROUND INFORMATION.

Retrieved September 25, 2011 from http://www.saps.org.uk/attachments/article/103/SAPS%20Scotland%20Estimating%20glucose%20concentration%20in%20solution.pdf

2. Student’s Handbook For Biology HL (Year 1) (2011). Kolej Mara Banting, International Baccalaureate – page 160-161.

3. Salman (2010). Estimating Glucose Concentration In A Solution. Retrieved September 27, 2011 from http://www.scribd.com/doc/40527047/DGCIaS-Bi0.