Natural pH indicator
Abstract
Title of this experiment is the acid-base indicator from natural dyes. This experiment is to investigate the colour variation of solution extracted from pigment of vegetable and fruit skin according to pH value and to deduce the ability of the extraction to act as an indicator in titration. The problem statement of this experiment is how does the colour of solution extracted from pigment of vegetable and fruit varies according to pH value of universal indicator and can it be used as an indicator in a titration. Method that have been used is measuring the pH and juices extraction. Household and laboratory item such as soap, concentrated sulphuric acid are tested with universal indicator to estimate their pH. The juice is then sieved and is added to respective test tube to observe the colour change. The materials that have been used are red apple skin, red cabbage and tomato. As for tomato,there is not much changes as it is colourless from pH 1-7 and become yellow from pH 8-13. Red cabbage shows a variation of colour change. It changes from red in acidic to pink in neutral and greenish yellow in alkaline medium. Red apple skin changes from red in acidic medium to pink in neutral and yellow in alkaline medium. As a conclusion, the colour changes are almost the same as the pH chart inserted in result section. Through this experiment, we realize that a lot of type of plants or fruits can be used as indicator besides the standard indicator such as phenolphthalein.
Title of this experiment is the acid-base indicator from natural dyes. This experiment is to investigate the colour variation of solution extracted from pigment of vegetable and fruit skin according to pH value and to deduce the ability of the extraction to act as an indicator in titration. The problem statement of this experiment is how does the colour of solution extracted from pigment of vegetable and fruit varies according to pH value of universal indicator and can it be used as an indicator in a titration. Method that have been used is measuring the pH and juices extraction. Household and laboratory item such as soap, concentrated sulphuric acid are tested with universal indicator to estimate their pH. The juice is then sieved and is added to respective test tube to observe the colour change. The materials that have been used are red apple skin, red cabbage and tomato. As for tomato,there is not much changes as it is colourless from pH 1-7 and become yellow from pH 8-13. Red cabbage shows a variation of colour change. It changes from red in acidic to pink in neutral and greenish yellow in alkaline medium. Red apple skin changes from red in acidic medium to pink in neutral and yellow in alkaline medium. As a conclusion, the colour changes are almost the same as the pH chart inserted in result section. Through this experiment, we realize that a lot of type of plants or fruits can be used as indicator besides the standard indicator such as phenolphthalein.