Soap Box Science

What usually happens when two liquids meet - when you pour milk into a cup of coffee, add food colouring to water, or combine two kinds of juice, for example? They mix, right? Well, that's not always the case. You and your child might be amazed by the results of this fun experiment.

Materials

• Clear glass or measuring cup
• Honey
• Syrup
• Tide® Liquid laundry detergent or Dawn® dish detergent
• Water in a small glass or measuring cup
• Food colouring
• Cooking oil
  

Instructions

Here are a few tips before you start the experiment:

• Add the food colouring to the water ahead of time, so it will be ready when it's time to add it to the experiment. If possible, use a colour that is different from the colour of the detergent and the colour of the cooking oil.
• During the experiment, hold the glass over a bowl or sink to catch any accidental spills.
• Be sure to add enough of each ingredient to cover the entire surface.
• It's okay to tip the glass gently as you pour the liquids down the inside - any ingredients already in the glass will stay in their layers as they slide.

Now let's get started. Carefully pour each of the liquids, one at a time, down the inside of the glass in the following order:

• Honey
• Syrup
• Tide Liquid laundry detergent or Dawn dish detergent
• Coloured water
• Cooking oil

You should end up with five fairly distinct layers of liquid in the glass.

What Happened?

Each liquid should have stayed in a separate layer on top of the previous liquid.

Why it Works

The liquids in the experiment stay in separate layers because they all have different densities. Density is mass (weight) per unit of volume - for example, grams/mL. The densest liquids go to the bottom, and the least dense liquids, which are more buoyant, stay on top.

Some of the liquids in the experiment - such as water and detergent - will eventually dissolve into each other (mix together). That process is sped up if you stir the ingredients or cover the container and shake it, or if you originally poured the liquids on top of each other instead of down the side of the glass.