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Blue precipitate when NaOH is added - Copper ion is present

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The moist red litmus paper turns blue, indicating that NH3 gas has evolved - Nitrate is present

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Only blue precipitate left - Iron ion is not present

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White precipitate present - Chlorine ion is present

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Akmal, Cheryl Low, Loke Jie Yi, Raudhah

Group 12

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Procedure:

1. Add NaOH dropwise. Record observations

2. Continue to add NaOH in excess if white precipitate observed. Record observations

3. Add aqueous NH3. Record observations

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Procedure:

1. Add HCl. Record observations

2. Add excess NaOH and Al foil

3. Heat strongly

4. Insert moist red litmus paper at the mouth of the test tube. Record observations

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Procedure:

1. Add NaOH / aqueous NH3

2. Record observations

3. If blue ppt is observed, Cu2+ ions might be present/ If dirty green ppt is observed, Fe2+ ions might be present. If reddish brown ppt is observed, Fe3+ might be present.

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Procedure:

1. Add excess HNO3 followed by AgNO3

2. Record observations

3. If white ppt is formed, Cl- ions could be present.

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Before conducting our experiment, we first filtered the water sample using a filter paper. We do so to ensure that there are no filtrate in the sample that we are using, ensuring accurate result.

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Our group decided to do Qualitative Analysis to test for the presence/absence of certain ions in the water sample given. The ions that we are testing for are:

1. Chlorine

2. Copper

3. Iron

4. Calcium

5. Nitrite

6. Nitrate

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The water is NOT SUITABLE for Koi fish breeding

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Ideal water conditions for breeding of koi fish:

Nitrate: Ideally at < 80 ppm. Limit to max 200 ppm.

Nitrates (NO3-) are generally harmless to koi, although koi had been observed to lose their appetite if the nitrate level is allowed to go unchecked.

Nitrite: Ideally at 0 ppm. Limit to max3 ppm.

Nitrites (NO2) at low levels can subject the koi to stress, making it vulnerable to diseases caused by other factors. High levels of nitrites cause skin and gill epithelia damage, which can lead to parasitic invasion or secondary bacterial infections.

Ammonia: water should be free from ammonia

At low levels (below 0.1 mg/liter), ammonia acts as a strong irritant to the koi, especially to its gills. Flashing may be exhibited by koi irritated by low levels of ammonia. Higher ammonia levels can lead to skin and gill hyperplasia.

pH: Ideally at 7.2-7.6 Limit at 6.5 min./8.2 max.

The pH of water affects the colour of the fish, acidic water results in a good red colour but a poor black and vice versa for alkaline water. Thus, a neutral pH would be ideal.

Well oxygenated: recommended 8-9 mg/l

Chlorine: water should be free from chlorine/ chloramine

Chlorine is toxic to koi fish

Phosphates: some phosphates will cause an increase in algae growth.

Calcium Carbonates (Hardness): about 100 ppm. Limit at 50 ppm min./150 ppm max.

Copper: water should be free from copper

Iron: water should be free from iron

Both copper and iron ions are toxic to koi. The gill surface may also have a substantial net negative charge, therefore having a high affinity for cationic metals. Copper ions precipitate gill secretions, causing death by asphyxiation.

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Chlorine Ion is present -> unsuitable for koi

Copper Ion is present -> unsuitable for koi

Iron Ions are not present -> suitable for koi

Calcium Ion is not present -> unsuitable for koi

Nitrite is not present -> suitable for koi

Nitrate is present -> suitable for koi