Density of various water samples

When you get into the water in a pool or a lake, you soon sink if you do not make swimming movements. In the Dead Sea is not so.
If you cool cans in a bucket of water, the cans of Coke sink, while the cans of Diet Coke might float on the water.
To help explain these phenomena, you should perform the following experiments involving tap water, "sea water", "Dead Sea water", Coke and Diet Coke.

Experiment

1. Comparison of water and "Dead Sea water“ with a "float": more see below

1. a) Fill one labeled infusion bottle with water and one with "Dead Sea water".
b) Put an empty sealed ampoule in each of the water samples. What do you observe?

2. Comparison of Coke and Diet Coke on the two-pan scale
Put on each of the scales one tea light cup and transfer with a syringe 5 mL Cola into one, and 5 ml of Diet Coke into the other. What do you observe?

3. Comparison of five water samples with a digital pocket scale
a) Switch on the scale, set a tea light cup on it and tare the scale.
b) Using the syringe, measure 2 mL each of the five water samples listed below; transfer them one at a time to the tea light cup, weighing them every time, and record the results in the table. Return the scale to 0.00g before each new measurement
c) Calculate for each sample the ratio of mass and volume (density).

Sample	Water	Diet Cola	Cola	„sea water“	„Dead Sea Water“
Mass m [g]
Density ρ [g/mL]

Tasks

1. Before performing experiments 1 and 2, predict what you would expect to see, and then check this experimentally.

2. Write down your observations.

3. Where do the differences in the masses or densities of individual samples come from?

4. Continue investigation of 3 with two additional self-chosen volumes. What do you notice? Explain the density term in your own words.

5. Explain the phenomena described above with the aid of your test results.

First published: 1995 Last modification: 15.05.2014