Awesome Acids and Bases

Today we got stuck into some more science and made sherbet using baking soda, citric acid, icing sugar and jelly crystals. Here's what we did...

METHOD:

1. First, add 1 level teaspoon of citric acid to the bowl.
2. Next, add 1 level teaspoon of bicarbonate soda to the bowl.
3. Now add 3 heaped dessert spoons of icing sugar.
4. Add at least 2 level dessert spoons of jelly crystals (or more to taste)
5. Place a small amount, about half a teaspoon on your tongue.
6. After tasting you may need to vary the ingredients. If it is too bitter add more sugar, if there isn't enough fizz you may need to add either bicarbonate soda or citric acid. 
7. Make sure you add only in small amounts, remember you can always add more but it is very hard to remove some.

WHAT'S HAPPENING

You have just created an acid-base reaction in your mouth. When you combine an acid (in this activity the citric acid) and an alkaline (the bicarbonate soda) with saliva they mix together to create a gas in the form of lots of tiny bubbles.

This is called an acid-based reaction and it's what gives sherbet its fizz. You are actually feeling the sensation of carbon dioxide bubbles on your tongue. These are the same bubbles that are in fizzy drinks.

The icing sugar is needed to add sweetness as the citric acid and bicarbonate soda are quite sour. Citric acid is one of the acids found in lemons, oranges and limes. That is why they are called 'citric fruit'. The other acid in lemons and other citric fruit is called ascorbic acid. This is commonly known as vitamin C. The jelly crystals simply add flavour.