Materials : Pineapple juice, 0.1% ascorbic acid solution, 2,6-Dichlorophenol – Indophenol (DCPIP) solution, distill water, filter paper. Apparatus : Small test tube and rack, 1cm3 and 5cm3 syringes with needles, 250ml beaker, 25ml measuring cylinder, stirrer, electronic scale. Methods
Part A: Standardization of DCPIP (Titrant) solution.
1. 1.00g of ascorbic acid tablet was measured by electronic scale and dissolved in 100.00ml of distilled water. 2. A 1.00cm3 syringe was used to transfer 1.00cm3of DCPIP solution into a small test tube. 3. A 5.00cm3 of syringe was filled up with 5.00cm3 of 0.1% ascorbic acid solution. 4. The needle of the 5.00cm3 was placed at the bottom of test tube and the ascorbic acid solution was slowly added until the DCPIP solution was decolourised.
5. The volume of the ascorbic acid used to decolourised the DCPIPsolution was recorded. 6. Step 2 to 5 was repeated twice to obtain the average volume of thr ascorbic acid solution used. Part B: Determination of the concentration of vitamin C in pineapple juice 1. A 1.00cm3 syringe was used to transfer 1.00cm3of DCPIP solution into a small test tube. 2. A 5.00cm3 of syringe was filled up with 5.00cm3 of pineapple juice.
3. The needle of the 5.00cm3 was placed at the bottom of test tube and the pineapple juice was slowly added until the DCPIP solution was decolourised. 4. The volume of thepineapple juice used to decolourised the DCPIP solution was recorded. 5. Step 1 to 4 was repeated twice to obtain the average volume of the pineapple juice used.