Do all substances mix?

15 minutes

Grease doesn’t mix with water. That’s why you can’t wash greasy hands and greasy dishes with pure water. Luckily, this can be fixed!

Requirements

Steps

Step 1

Pour water into the drinking glass until it is about half-full. Then pour in some salad oil until it forms a clearly visible layer. What do you see?

Step 2

Using the spoon, stir the contents of the glass forcefully but carefully. What happens now? Is the salad oil mixing with the water? Are there any changes as time passes?

Step 3

Put a few drops of washing-up liquid into the drinking glass. Stir the contents again. Can you see any differences compared to the previous step?

Step

What did you discover

This experiment clearly shows why we use washing-up liquid when washing dishes. Greasy materials like grease and oil don’t dissolve well in pure water, which means you’ll never get your plates clean.

For spotless dishes, you need to add washing-up liquid, so the greasy materials will mix better with the water. Washing-up liquid is an additive for dissolving grease in water.