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Titration almost over

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Titration in progress

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After filtration

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Based on the results obtained, the water sample from the pond contains nitrites with a concentration of 961ppm. The concentration found has drastically exceeded the maximum concentration of NO2-required for the healthy breeding of Koi fish which is 0.25ppm. Thus, we can conclude that the pond is not suitable for the breeding of Koi fish as the concentration of nitrites present is too high and is toxic to the Koi fish.

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Qualititative analysis:

NH4+ and NO2- ions were present in the water sample.

NO3-, Br-, Cl- and I- ions were absent.

Quantitative analysis:

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To determine whether the conditions of the water sample are suitable for the healthy breeding of Koi fish by testing for the presence and amount of certain ions. (i.e NO2- ions)

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Qualitative Analysis:

1.Testing for NH4+ ions: Add NaOH and heat strongly. The gas evolved will turn moist red litmus paper blue.

2. Testing for NO2- ions: Add HCl. If a colourless fume which turns brown after extended contact with air is observed, NO2- is present. Add excess NaOH and Al foil and heat the solution strongly. After heating the sample, a pungent gas which turns moist red litmus paper blue will be evolved.

3. Testing for NO3- ions: Add HCl followed by excess NaOH and Al foil and heat strongly. The only observable change will be the gas evolved turning moist red litmus paper blue.

4.Testing for Br-, Cl- and I- ions: Add excess HNO3 followed by AgNO3. White precipitate indicates the presence of Cl- ions. Cream precipitate shows the presence of Br- ions and pale yellow precipitate means there are I- ions present.

Quantitative Analysis:

1.Testing for PH value

1)Filter 20cm3 of water sample into the colonial flask

2)Drop a few drops of Bromothymol Blue(indicator) into the water sample,determine the nature of the smaple,whether it is acidic(blue) or basic(yellow)

3)Based on the acidity of the sample,add in H2SO4 or NaOH solution into the burette.

4)Conduct the tittration.

5)Determine the amount of acid or base added into the solution for the indicator in the sample to change back to green, and calculate the concentration of H+ or OH-.

6) Calculate the PH value of the sample see whether it falls between the healthy range.

2 Testing for the concentration of NO2- (redox reaction)

1)Filter 20cm3 of the water sample

2)Conduct titration using acidified KMnO4 solution(purple),titrate until the sample turns from blue to deep blue(almost purple)

3)Based on the amount of KMnO4 solution we used in titration, calculate the concentration of NO2-, and see whether it is within the limit.

The actual procedures:

1.Test for the presence of Cl-, Br- and I- ions.

2. Use a fresh sample and test for the presence of NH4+ ions. Heat the sample until the moist red litmus paper does not turn blue any more, meaning no more NH4+ is present in the sample.

3. Use the solution we get from step 2 to test for the presence of NO2-.

4. Acidify KMnO4.

5. Conduct titration using acidified KMnO4 solution(purple),titrate until the sample turns from blue to deep blue(almost purple).

6. Record the data and repeat step 4 to 5 once.

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At the research phase, we searched for the water conditions for the healthy breeding of Koi fish on the Internet and found out a list of factors that contributed to the water quality and affected the health conditions of Koi fish. These factors includes the amount of ions, the amount of dissolved oxygen, the pH value of the water body, etc. The details are as follows:

1. Oxygen levels should not be lower than 5.0 mg/L for koi.

2.The pH value should varies from 6.8 to 8.2. A pH value of 7, meaning the water is neutral will be the ideal condition.

3.The amount of ammonia should be less than 0.1ppm. The amount of nitrites should be less than 0.25 ppm and the amount of nitrate should be less than 60ppm. The water will be toxic and not suitable for the Koi fish to survive if there are too much of the above substances. The water condition will be ideal if the readings of ammonia and nitrite are both zero.

4.Besides the above factors that we are familiar with in chemistry research, there are also factors suchas alkalinity, salinity and the hardness of water that have an impact on the health of Koi fish. Ions that contribute to these faxtors are Mg2+, Ca2+, (CO3)2-, HCO3-,Na+ and so on.

References:

http://www.koifishponds.com/waterqual.htm

http://koi-care.com/ideal-water-conditions-healthy-koi/