Thursday, 31 May 2007

Why the bacteria experiment works and what to do next:

What to do next:

Rub a little Vaseline on the tip of the vials to make it easier to complete the next step.

Attach a vial to each syringe.

What will happen:

What will happen now is that when the bacteria in the water is breathing, the bubble will go up the vial, showing how many mLs of oxygen the bacteria are consuming. This is relevant because the more bacteria, the more oxygen consumed, so for example, the tap water consumed more oxygen, that means there is more bacteria in the tap water than any other sample of water.

We needed to soak the cotton balls in Potassium Hydroxide, because Potassium Hydroxide will absorb the Carbon Dioxide in the air, making it a healthier environment for the bacteria to thrive in.

Now, we need to record every 5 minutes how far the bubble has gone up the vial.

Then we find the average of oxygen consumed per minute using the calculator.

My Method

Testing for Chlorine: Using the ‘Magnor’ Test Kit

1. Fill the CL test tube with one of the different waters.

2. Add one DPD tablet to the test tube. Avoid touching the tablet.

3. Place cap on tube and shake to mix contents.

4. Compare tube colour with chlorine colour scale.

5. Once recorded results, clean tube and test other water samples.

Testing for pH: Using the ‘Magnor’ Test Kit

1. Fill pH test tube with one of the different testing waters.

2. Put 5 drops of Phenol Red soloution into test tube.

3. Place cap on tube and shake to mix contents.

4. Compare tube colour with pH colour scale.

Once recorded results, clean tube and test other water samples.

Testing for bacteria:

Making the Potassium Hydroxide mixture:

Mix up Potassium Hydroxide tablets with 50mLs of water.

Shake Potassium Hydroxide mixture.

Making the bubbles for the vials:

Mix 5-10 drops of food colouring with a little water in a glass or mug. The amount of water will not affect the experiment.

Using vials, release a small amount of water/food colouring into each vial, making a bubble.

Preparing the 60mL syringes:

Put 200mLs of each test water into each container.

Mix 1 gram of sugar with each water and stir.

Then take 1 mL of each water and squirt it in each syringe.

Then put one cotton ball in each syringe.

Then dip the three remaining cotton balls in the Potassium Hydroxide mixture.

Put one Potassium Hydroxide dipped cotton ball in each syringe.

My Variables

Measured Variable: I will measure the mLs of oxygen the bacteria are consuming and the pH, chlorine, iron and copper levels.

Test Variable: I will change the water to see which is the healthiest.

Control Variable: I will keep the temperature of the water the same and also the amounts of water, sugar, chemicals etc.

Tuesday, 29 May 2007

My Apparatus That Is To Be Used


Apparatus to use when testing for bacteria:



Cotton Balls x6
Potassium Hydroxide tablets (7.5 grams)
3x 2mL Vials
3x 60mL syringes
Vaseline
200mL filtered water
200mL tap water
200ml pond water
3grams of sugar
50mL water to mix with tablets
20mL water to make bubbles
5-10 drops of food colouring (any colour)
1 pair of gloves
1 glass or cup
1 stopwatch
1 calculator
1x 1mL syringe


Apparatus for testing for Chlorine and pH:

1x Chlorine and pH testing kit
Water to test (filtered, tap, bottled, distilled)

My Aim and Hypothesis

My Aim:

To determine whether filtered water, bottled water, tap water or distilled water is the healthiest, by checking the pH, chlorine, iron, copper and bacteria levels of the waters.

My Hypothesis:

I think that distilled water will be the healthiest because it is taken from boiled water, making it sterile. I also think that tap water will be the worst because it is not as purified as the other options.

Monday, 28 May 2007

A Great Find!

Over the weekend I discovered something really interesting from Antony, my friend's uncle, who has a PhD in science. He told me that all water has bacteria, so it would be a little pointless in counting the colonies of bacteria in my water. But I could find the breathing rate of the bacteria, which would sort of show how much of it is in there, because of this:

For Example: If there are heaps of mice in a jar, and only one mouse in a jar, the jar with a lot of mice will run out of oxygen faster than the jar with only one mouse. This happens because the more living things, the more oxygen consumed. Because of this, I can see which water will run out of oxygen first, which will show which water has more bacteria.

I'll keep the blog up to date with pictures.

Saturday, 26 May 2007

My Latest Discoveries


Today I bought a test kit for my project. It will test for pH and Chlorine.



I also found out about the normal requirements for water. Take a look at them.

Iron: Too much iron may stain things. The normal amount is 0.3mg to 1ppm).

Hardness: For water to be moderately hard, it needs to have 3.5 grains to 7 grains of hardness.

Copper: The more copper makes water worse. The normal amount is 1.3ppm.

Chlorine: It is good to have 0.1 to 4mg, because it reduces bacteria growth.

pH: pH measures acid and alkalinity. A pH of 7 is neutral.

Welcome to my Science Log

My name is Cheyenne and I am in an Intermediate school in Year 7. On this blog, I will record all my interesting events, pictures and more to do with this year's Science Fair.

For 2007, my science fair project will be about water. I will see whether filtered, tap, bottled or distilled water is the healthiest. I will test for pH, chlorine, iron, hardness, copper and possibly bacteria.

Keep a look at my blog over the next several weeks to see what I am up to.