Solution

Homogeneous mixture of particles so small that they cannot even be seen with a microscope and will never settle to the bottom of their container.

• E.g. Vinegar, Soda (unopened), hydrogen peroxide

Colloid

Type of mixture with particles that are larger than those in solution, but still too light to settle out.

• E.g. Milk (water and fat), Fog (water and air), Whipped cream

Detecting colloids is sometimes difficult so shining a beam of light at colloid will make light scatter- this scattering of light by a colloid is called the Tyndall effect.

Suspension

Heterogeneous mixture containing a liquid in which visible particles settle.

• E.g. Italian dressing, muddy pond water, chocolate milk.

If it needs shaking to mix, then its a suspension.

Making Sherbet mixture:

Materials:

• citric acid

• bicarbonate soda

• icing sugar

• flavoured jelly crystals

• teaspoon

• dessert spoon

• small mixing bowl

• small plastic cup.

METHOD

1. Place all ingredients into a small bowl and mix well.

• 1 tsp baking soda, 1 tsp citric acid, 3 Tbsp icing sugar, 2 Tbsp flavoured jelly crystals)

HINTS

To increase the sourness, add an extra teaspoon of Citric acid to the mixture. To increase the sweetness, add more icing sugar to the mixture. *available near the baking powder in the supermarket

What is happening?

You have just created an acid-base reaction in your mouth. When you combine an acid (citric acid) and an alkaline (the bicarbonate soda) with saliva they mix together to create a gas in the form of lots of tiny air bubbles. This is called an acid-base reaction and it's what give sherbet its fizz. You are actually feeling the sensation of carbon dioxide bubbles on your tongue. There are the same bubbles that are in fizzy drinks. The icing sugar is needed to add sweetness as the citric acid and bicarbonate sode are quite sour. Citric acid is one of the acids found in lemons, oranges and limes. That is why they are call '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.