Introduction:
You may have noticed that gas prices have been going up. It turns out that they always go up in the spring because the gasoline that is provided in the winter is different than the fuel provided at other times of the year. Why? A simple bubble experiment will show us.
Materials:
- Transparent bottle (glass or plastic) – the bottom of it must be able to fit into the bowls of water
- Dish soap (1 tsp with 1 tbsp water – 1 tsp of corn syrup would enhance the strength of the bubble)
- Bowl of hot water
- Bowl of ice water
Safety:
The hot water can come from an electric kettle, microwave oven or even tap water, but care must be taken to avoid getting burned.
Experiment:
Once the dish soap mixture is stirred well, tip the bottle upside down into it and make sure that there is a layer of soap film covering the opening of the bottle.
Place the bottom of the bottle into the hot water and see what happens. Then, place the bottom of the bottle into the ice water and notice any changes. You can go back and forth between the containers. If the bubble breaks, simply get a new layer formed by putting it back into the soap mixture.
What’s Happening?
ChemShorts, as recently as January 2023 showed an experiment very similar to this one. In it we find that as the temperature of the air goes up, the air molecules speed up and as they do so they take up more space. If the molecules take up more space, this will cause the bubble to force its way up and out of the bottle.
Likewise, as the temperature cools, the molecules get closer together and the bubble will be pushed inside the bottle. What does this experiment have to do with cars? A car needs to have a specific amount of gasoline molecules in the combustion chamber, the gas companies put lower boiling point molecules (like cheap butane) into the gasoline mixture in the winter and higher boiling point molecules into the gasoline in the summer.
Extension/Final Notes:
Does the size of your bottle make a difference? Does it make a difference if your water levels are higher or lower?
Resources:
https://lsc.org/news-and-social/news/bubbles-move
https://www.caranddriver.com/news/a15339380/the-vapor-rub-summer-versus-winter-gasoline-explained/
To view past “ChemShorts for Kids” activities, go to:
https://chicagoacs.org/ChemShorts.
