Q&A for How to Find the Density of Water

Near the freezing point, water actually expands as it cools, making it less dense.

Find the volume of the marbles (by water displacement), weigh the marbles, and divide their weight by their volume.

You can add different solvents to change the density. For example, dissolving salt will increase the density.

The volume measurement is being divided by the mass, so the density would be different from what it really is supposed to be.

It isn't. Density is mass per volume, essentially the weight of the water that fills a given space. It happens that in the metric system one gram of water fills one milliliter of space, but that one-to-one relationship does not exist in other measurement systems.

The average motor (engine) oil is about 30% denser than petrol/gasoline.

Follow the instructions above. Expect the density to be higher than it is with cleaner water.

Density is simply weight per volume. You collect a known volume of water and weigh it.

Temperature does affect density to a small extent. In the case of water, it does expand if it freezes, and it will evaporate if it boils, in either case changing the density. All you can do is measure instantaneous volume and weight at a given temperature. In the case of boiling water, measuring precise volume is difficult.

Generally speaking, the density of a liquid (and most other matter) varies inversely with temperature.

Density = mass of volume. Mass = 50g. Volume = (65 - 40)cm^3 = 25cm. Therefore, Density = 50g/25cm^3 = 2g/cm^3.

No, because you'd essentially be finding the average density of both the water and the graduated cylinder combined, as opposed to just the density of the water.