Chemistry

What did we do? We measured the O2, temperature and pH of different water samples

In this experiment, we measured the percentage of oxygen in three different types of water: Tap, lake and pond water. We also measured the temperature of these samples of water. We had thought that pond water and lake water would be similar in temperature due to how they are almost always exposed to the outside and the temperatures of day and night. The oxygen levels however we thought would be the highest in the lake or tap as there is usually fresh flowing water in the lake and in the tap.

We used an oxygen probe that was connected to a LabQuest to measure the concentration of oxygen in the different samples of water. We measured for 15 seconds on each one, rinsing the probe in distilled water after each measurement. The temperature was measured using a heat probe, which we left in for a minute beforehand in order to obtain accurate results of the temperature. The pH level was obtained using pH paper, with the help of a key for the different colours allowed us to easily identify the different pH levels of the water samples.

Analysis of the data:

• From our data we can clearly see that tap water has the highest percentage of oxygen in the water. This is mostly due to how there are no plants and animals in the water which could take up oxygen, whereas in the lake and pond water, organisms such as pondweed and fishes usually take in oxygen. The temperature of the water is close to being the same, aside from the tap water which may have absorbed heat being stored underground or in a pipe which would heat up during the day.
• The Ph of the water is alkaline due to the water being known as 'hard water' which is due to its dissolved mineral content. We can see that these minerals had been mostly taken out of the tap water which is why the pH would be much closer to 7.

Overall we can conclude that the difference in Oxygen levels with each sample of water from different locations is not significant. The only significant change is the pH of the water due to the removal of minerals and ions in the water that is pumped in.