Which is denser, isopropyll alcohol (rubbing alchohol) or water?

Isopropyll is less dense than water.

If you were to get a gallon of water and a gallon of Isopropyll alcohol and weigh it, the alcohol would be lighted. Another way is to pour water and the alcohol in a cup and you will see that the alcohol is above the water (floating) because its lighter and less dense. Isopropyll alcohol is used for a lot of things, including cleaning certain components of computers:D

So based on this, water is more dense