|Construct |Sample Answers | |1. Objective |To determine the concentration of vitamin C in the samples of fruits. | |2. Problem |Able to relate P1, P2 and H in a question form. | |Statement | | | |Sample answer: | | |Which fruit juice has a higher concentration of vitamin C? | |3. Hypothesis |Able to relate P1, P2 and H | | | | | |Sample answer: | | |Guava juice contains higher concentration of vitaminC compared to pineapple juice and orange juice. | |4.
Variables | | | | | |Manipulated : |Type of fruit juice | |Responding : |Concentration of vitamin C | |Fixed : |Concentration of ascorbic acid solution / Volume of DCPIP solution | |5. Materials and |Materials = DCPIP solution, 0. 1% ascorbic acid solution, pineapple (juice), orange(juice) and guava | |Apparatus |(juice). | | | | | |Apparatus = syringes with needles, measuring cylinder and specimen tubes. | |6. Technique |Measure and record the volume of fruit juice needed to decolourise 1 ml of DCPIP solution using a | | |syringes. | | | | |7.
Procedure |K1 – Preparation of materials & apparatus | | |Place DCPIP solution in the specimen tube using a syringe | | |Fill the syringe with ascorbic acid solution | | |Add the ascorbic acid solution into the DCPIP solution until the DCPIP solution is decolourised | | |Repeat the experiment using 1 st manipulated variable (fruit juice) | | |Tabulate all data | | |Calculate the percentage/ concentration of vitamin C in each fruit juice/volume of fruit juices needed | | |to decolourise 1 ml of DCPIP | | | | | |
K2 – Operating Fixed Variable | | |Volume or concentration of DCPIP solution mentioned and fixed in each experiment | | | | | |K3 – Operating Responding Variable | | |Measure the volume of fruit juices used to decolourise the DCPIP solution // Record the volume of fruit | | |juices used to decolourise the DCPIP solution in a table. | | | | | |K4 – Operating Manipulated.
Variable | | |Use different type of fruit juices in each experiment i. e guava juice, pineapple juice and orange juice| | | | | |K5 – Precaution / Accuracy of experiment (Any one) | | |place/immerse the needle of the syringe into the DCPIP solution | | |do not shake the tube vigorously | | |repeat the experiment for each fruit juice to get the average volume of fruit juice used to decolourise | | |the DCPIP solution | | | | | |* Refer to ‘Sample Procedure’ | |8. Recording |Able to construct a table to record all data with the following aspects : | |data |3 titles with correct units ( where concern ) | |( Results ) |No data is required | | | | | |Refer to ‘Sample Results’ | |9.
Conclusion |Guava juice contains higher concentration of vitaminC compared to pineapple juice and orange juice. | | | | |Planning of Experiment |7 – 9 ticks = 3m | | |4 – 6 ticks = 2m | | |1 – 3 ticks = 1 m | | | | Sample Procedure : 1. 1 ml of DCPIP solution is placed in the specimen tube using a 1 ml syringe. 2. The 5 ml syringe is filled with 0. 1% ascorbic acid solution. 3. The needle of the syringe is placed into the DCPIP solution 4. Ascorbic acid solution is added drop by drop to the DCPIP solution, and gently stirred with the needle of the syringe. Do not shake the tube vigorously. 5. The ascorbic acid solution is continuously added until the DCPIP solution is decolourised. 6. The volume of ascorbic acid solution used is recorded. 7.
Steps 1 to 6 are repeated using fresh guava , pineapple and orange juice. 8. The volume of fruit juice required to decolourise the DCPIP solution in each fruit juice is recorded in a table. 9. The percentage and the concentration of vitamin C in each fruit juice are calculated. Sample Results : |Solution/fruit juice |Volume of solution/fruit juice needed to decolourise 1ml of DCPIP |Concentration of vitamin C(mg cm-3) | | |solution (ml) | | | | | | | | | | |1 |2 |3 |average | | | | | | | | | |0. 1% ascorbic acid | | | | | | | | | | | | | |Guava juice | | | | | | | | | | | | | |Pineapple juice.