Add water to ethanol and find out why it doesn’t add up. It’s similar to what happens when you mix a liter of sand and a liter of rocks. When mixed, the combined molecules fit together better than alone, so they take up less space. What’s more, the OH- component of the ethanol and the H+ of the water molecules are attracted to each other – creating hydrogen bonds. These bonds make a tight molecular formation, reducing the volume of the combined liquids.
- 100ml of water
- 100ml of ethanol (with adult supervision)
- Three graduated cylinders – two smaller to measure out the liquids, and one larger to mix and read off the resulting volume.
Measure out exactly 100ml of water and 100ml of ethanol.
Add the two solutions together in the large graduated cylinder and look at the measurements.
You would expect the resulting solution to measure exactly 200ml, however it should actually give a volume of around 192ml.