Hello again!
We hope you have enjoyed the session with us at Homeschool Science Fun Day! It was nice to have you graced our booth and after much thought, we have decided to add the three extension activities on Acid and Alkali through pH.
Before you proceed to the three activities, you will need the following items:
– a white piece of paper – a petridish (or a transparent apparatus you can use to hold the liquid sample) – a dropper – red cabbage juice – pH indicator chart
Watch this video to learn how to make your own red cabbage juice.
This is the pH indicator chart for red cabbage juice.
Activity 1 Fruits and Vegetables
Make a list of five of your favourite fruits and five of your favourite vegetables.
Next, squeeze the juice from the first fruit in your list onto a petridish.
Place the petridish on a white piece of paper.
Taste the juice.
Using a dropper, put 5 drops of the red cabbage indicator on the juice and observe the color change. Based on the pH indicator chart, write down its pH level.
Record your data in the table here.
Conclude by deducing if the item is acidic or alkaline.
EXTENSION ACTIVITY
Do you know there are two types of acid present in fruits? One is citric acid and the other is ascorbic acid.
Citric acid is responsible for the sour taste in fruits. While ascorbic acid is the Vitamin C which your body needs. There are many benefits of citric acid and ascorbic acid. One of them is replenishing your skin. However, taking excessive of citrus fruits, especially on an empty stomach may cause stomach upset due to the presence of excessive acid in your stomach.
Which one of the fruits has a higher acid content? Why?
Activity 2 Saliva test
Draw a table to record the pH of your saliva at different times of the day. (Or you can download the table here.)
These are the recommended intervals: – morning (right after you wake up and before you do anything like eating or brushing your teeth) – an hour after your breakfast. – an hour after lunch – an hour before dinner – an hour after dinner – right before bedtime
Before you do any saliva test, swallow your saliva at least 3 times before spitting out to test for the pH on a petridish.
Place the petridish on a white piece of paper.
Using a dropper, put 5 drops of the red cabbage indicator on the saliva sample on the petridish.
Observe the color change.
Based on the pH indicator chart, write down its pH level.
Repeat this experiment for a week or two.
At the same time, record the food you eat during your 3 main meals.
Observe the pH level of your saliva and make a conclusion.
EXTENSION ACTIVITY
The pH level of the saliva of a healthy person when he just wakes up will be about 6.8. This pH level also tells us of the type of food eaten the night before. While we are sleeping, our body systems are hard at work. Some of the things that they do is to remove any toxic waste in our body, repair damaged tissues and replenish the state of the body. A low pH is an indication that the body is acidic and lacking the alkalizing properties of a healthy body.
After your meals throughout the day, your body should be measuring borderline alkaline as that is the optimum pH for a healthy body.
Look at the data you collected again. Is your body in the optimal range? Do you think you can improve based on the food consumed?
Activity 3 Wash, Wash, Wash!!!
List 10 cleaning products that you use frequently.
Draw a table to record the pH level of each of the cleaning agent. (Or you can download the table here.)
Make a solution from each of the cleaning agent. Pour gently into a petridish.
Place the petridish on a white piece of paper.
Using a dropper, put 5 drops of the red cabbage indicator on the solution.
Observe the color change.
Based on the pH indicator chart, write down its pH level.
Now, make a conclusion from your observations and records.
EXTENSION ACTIVITY
Our skin has a thin and protective layer on its surface. It is called the acid mantle. The surface of the skin has a pH of approximately 5.5.
This acid mantle is made up of free fatty acids that are excreted from the skin’s glands, which mixes with lactic and amino acids from sweat to create the skin’s pH. Usage of extremely alkaline cleaning agents can strip away the protective layer (acid mantle) causing the skin to be dry and irritated.
Which of the cleaning agent do you think have a drying effect on the skin? Why?
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DO YOU KNOW….
Do you know what makes an acid stronger than the other? Do you know why different pH gives different colors in the presence of a pH indicator?
Do you know what makes an alkali stronger than the other? Do you know why different pH gives different colors in the presence of a pH indicator?
Do you know that there are other pH indicators with different colour changes in different pH?