Science Thursday: Frozen Expansion

(For any newcomers, this is a semi-regular series on science experiments that we do as part of our homeschool curriculum.)
After our last science fiasco (OK, so the fiasco wasn’t actually science related), I was looking forward to a more normal science day. Thankfully everyone is back to full health.

We’ve started a unit on weather experiments. We were scheduled to do some experiments on rain, but due to a cold snap, where temperatures have dipped down into the teens at night, we went ahead and did the lesson on cold weather instead.

We talked about what happens to water when it gets cold–It turns to ice.

We then, asked the question: Why does ice float? You’d think that it would be heavier than water, but it is actually lighter. The kids have these Magnetix toys, and we used those to demonstrate how the bonds between the water molecules form holes in the structure of ice, so that it is actually lighter than liquid water.

Our experiment was to fill a bottle with water and cover the mouth with a coin.We would then freeze the bottle and the expanding ice would push the coin up.

It didn’t exactly work as advertised. Instead of pushing the ice up through the bottle opening, the bottle swelled up like a tick on a dog. It actually expanded so much that it broke the wrapper on the bottle:

After it snowed later in the week, we did a second experiment. We filled a jar to the brim with snow, let it melt, and then measured how much water was left in the jar (less than half). We talked about how snow has a lot of air in it, and so the same amount of liquid water takes up less space.