Name: Leong Han Juin Class: 4S3 Teacher: Puan Chan Yoke Bee
Tittle: Use Natural Ingredients as pH indicators Aim: To study the effect of natural ingredient towards acid and alkali Problem statement: Do acid and alkali change the colour of red cabbage juice? Hypothesis: Acid and alkali will change the colour of red cabbage juice Materials: Lemon, Cherry tomato, Vinegar, Soup water, Shampoo, Chlorox, Red cabbage Apparatus: Plastic bowl, Kettle, Blender, Knife Procedure: 1. The red cabbage is blended into a liquid state and used as a pH indicator. 2. The red cabbage water is mixed with lemon in a liquid state. 3. Step 3 is repeated but the lemon is displaced by tomatoes, vinegar, chlorox, shampoo and soap water. 4. The colour formed is recorded. Results: Chemicals Colour with Indicator Acidic or Alkaline? Lemon red Acidic Cherry tomato red Acidic Vinegar red Acidic Soup water bluish-green Alkaline Shampoo bluish-green Alkaline Chlorox greenish-yellow Alkaline
Interpreting data: Red cabbage contains a water-soluble pigment called anthocyanin that changes colour when it is mixed with an acid substance or an alkaline substance. The pigment will turn red when expose to acid environment with a pH less than 7, and the pigment turns bluish-green or greenishyellow in alkaline environments with a pH greater than 7. Discussion: 1. Introduction to pH indicators and their importance pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH of the solution can be determined visually by changes in absorption or emission of properties. We have many types of pH indicators such as phenolphthalein, litmus paper, litmus solution, methyl orange and others. Different colours are formed when different pH indicators are used. For instance, methyl orange shows red in acidic medium and yellow in alkaline medium. The importance of pH indicator is can reflect the chemical condition of a substance and know the pH value of a chemical substance in liquid state. 2. Explanation of how natural ingredients can be used as pH indicators Many red, purple, and blue plants contain chemicals called anthocyanins, which are weak acids that dissolve in water and change colour in response to changes in pH. Because of this, plants with anthocyanins like red cabbage and blueberries can easily be made into pH indicator. 3. Description of the experiment conducted, including materials used and procedures followed The experiment is to study the effect of natural ingredient towards acid and alkali. The material we used are lemon, cherry tomato and vinegar acting as acid substances, while also
soup water, shampoo and chlorox acting as alkali substances. Last but not least, red cabbage will be blended into liquid state to form a natural pH indicator. The procedure of the experiment is firstly, the red cabbage is blended into a liquid state and used as a pH indicator. After that, the red cabbage water is mixed with lemon in a liquid state. Then, repeating the same step but the lemon is displaced by tomatoes, vinegar, chlorox, shampoo and soap water. Lastly, the colour formed is recorded. 4. Results obtained from the experiment conducted, including materials used and procedures followed Red cabbage in liquid state contains anthocyanin pigments that change colour depending on the acidity or alkalinity of a solution. The acidic nature of lemon, cherry tomatoes and vinegar turn the natural pH indicator into a pinkish-red colour. On the other hand, soup water, shampoo and chlorox turn the natural pH indicator into bluish-green and greenish-yellow colour. 5. Discussion of the significance of the results obtained, and their relevance to real-world appliactions. From the result obtained, we can conclude that some natural ingredients such as red cabbage, turmeric and beet juice can be used as pH indicators. Therefore, we can use these common natural pH ingredients to determine the acidity or alkalinity of substances instead of buying proper pH indicators. Conclusion: Hyphothesis is accepted. Acid and alkali will change the colour of red cabbage juice