Prediction
The experiment involves measuring the height of the lather when soap is added to the 5 different types of water. Soft water contains Sodium (Na) ions which bond with the soap to make lather, in contrast to the hard water, it contains less Na ions therefore it should produce less lather. Based on this theory I predict that the more lather that appears in the test tube the softer the water should be.
Method
Apparatus:
- 5 Test tubes
- 2 Test tube racks
- Beaker
- Measuring cylinder
- 5 Samples of water labelled A to E
- Ruler accurate to 1mm
- Soap
- Distilled Water
- Syringe
The experiment shall have 5 samples of water, which beforehand shall be heated to boiling temperature (by use of a Bunsen burner) to make soft water. To make this experiment a fair test, I will use the same test tubes and the same amount of water for each test tube, which is 4ml and I will be using a measuring cylinder to measure this amount accurately. I will also use the same soap and the same amount of soap for each test tube. The lather shall be measured using the same ruler, which will be accurate to 1mm. For the Ph, chloride, carbonate and sulphide test, the same amount of drops of the respective solution shall be used accordingly.
Lather test
A B C D E
- 4ml of the boiled water will be placed into each test tube using a measuring cylinder
- One spatula of solid soap will be placed in separate test tubes, along with distilled water to make a soap solution will be placed into the test tubes labelled A to E
1 spatula of soap solution with distilled water
These test tubes are separate to the other test tubes.
- We will now put 0.5ml of the newly made soap solution into the test tubes labelled A to E. The test tubes will then be shaken 5 times, again making sure this is a fair test, all the test tubes will be shook the same amount of times.
0.5ml of soap solution into the test tubes
A B C D E
- The height of the lather in each test tube will be measured with the ruler.
The next series of tests are to clarify and back up the prediction that I have made earlier. We are testing the water for different chemical presences and Ph variation to see the hardness of the water.
Ph test
The water samples will now be tested for their Ph value. Softer water is close to Ph 7 so testing these water samples will give us a more accurate result, as with the same with the other tests after this one.
Using a pipette, 3 drops of universal indicator shall be dropped into the test tubes
A B C D E
Test for Chloride
Using a pipette, we will put 4drops of silver nitrate solution into each test tube
In case of a presence of a Chloride there will be a white precipitate in the participating test tube thus showing the hardness of the water sample.
Test for Carbonate
Using a pipette, put 4 drops of hydrochloric acid into each test tube
If there is a presence of a carbonate then there will be a white precipitate
Testing for a sulphide
Using a pipette put 4 drops of Barium Chloride into each test tube
If there is any white precipitate then there is a presence of sulphide, and as a result of that the water is harder.
Obtaining evidence
Carrying out the investigation
Test 1: Testing the differing test tubes (a-e) for their relative
Hardness.
Test 2: Testing the different solutions for their different ph
Test 3: Testing for a Chloride
4 drops of Silver Nitrate
Test 4: Testing for a Carbonate
4 drops of Hydrochloric Acid, shake 5 times
Test 5: Testing for Sulphide
4 drops of Barium Chloride, shake 5 times
Analysis
Here I shall show the graphs for the three experiments
Here is the graph for the average height in lather, for all the test tubes
Conclusion
In my conclusion, I conclude that Test tube C had the softest water, as the most lather was produced in that particular test tube. In relation to my background theory earlier, the softest water would produce the most lather, which is what I had concluded here.
Evaluation
I think generally the experiment was succesful, Test tube C seemed to have the softest water, mistakes of course wouldve caused a difference in the graphs and the statistics. In short, I produced results that was consistent to the theory of the hardness of water and prediction that I made at the start.
What I could’ve done to improve my experiment:
- Repeated the experiment more times to get greater accuracy
- Used more water samples, a greater variety for more accuracy
I think application of these things wouldve given a wider range of possibilties open for interpretation, the results wouldve been more reliable, as they were based on more variables.