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Watching what happens when different liquids are poured into the same jar.
Have you ever wondered why oil on a rainy puddle looks like a shiny rainbow instead of disappearing into the water? It is because some liquids are secret 'un-mixables'!
Some liquids are like best friends—they love to hang out together! When you pour water and fruit juice into the same glass, they blend perfectly. This is called a uniform mixture. Once they are mixed, you cannot see the water and the juice separately anymore. They become one new liquid that looks the same from the top of the glass to the bottom. Most liquids we drink, like milk or squash, mix with water this way.
1. Take cup of clear water. 2. Add spoonful of bright orange juice. 3. Stir them together for seconds. 4. Notice how the whole cup turns light orange. You can no longer see the clear water!
Quick Check
If you mix two liquids and they look exactly the same all the way through, did they mix completely?
Answer
Yes, they formed a uniform mixture.
Not all liquids want to be friends. Some liquids are immiscible, which is a big science word for 'not mixing.' Oil and water are the most famous examples. Even if you shake a jar of oil and water very hard, they will eventually pull away from each other. The oil will always find its way back to the top, and the water will stay at the bottom. They prefer to stay in their own space!
1. Fill a jar halfway with water. 2. Pour tablespoons of vegetable oil on top. 3. Watch as the oil beads up and floats. 4. Stir it quickly with a spoon. You will see tiny bubbles of oil, but as soon as you stop, the oil bubbles climb back to the top to form a layer again.
Quick Check
Which liquid usually sits on top when you mix oil and water?
Answer
The oil sits on top.
When liquids do not mix, they form layers. It looks like a colorful sandwich inside your jar! The liquid that is 'heaviest' (most dense) will sink to the very bottom. The 'lightest' liquid will float at the very top. The clear line you see between two layers is called a boundary. Scientists use these layers to tell different liquids apart without even tasting them!
Imagine you have three liquids: Honey, Water, and Oil. 1. Pour the honey in first. It is very heavy and thick. 2. Gently pour blue-colored water over the honey. 3. Finally, pour yellow oil on top. 4. You will see distinct layers: Honey at the bottom, Water in the middle, and Oil at the top. They will stay this way as long as the jar is still!
What happens when you mix water and food coloring?
If you see a jar with yellow liquid on top and clear liquid on the bottom, what are you looking at?
Oil and water will eventually mix if you leave them alone for a long time.
Review Tomorrow
Tomorrow, try to remember the name of the line that separates two layers of liquid (Hint: it starts with a 'B').
Practice Activity
With an adult, try mixing different things from the kitchen like syrup, milk, or vinegar with water to see which ones are 'mixers' and which ones are 'layers'!