““We are surrounded by We are surrounded by water but there is no drop water but there is no drop

to drink”to drink”Task 3. Chemical experiment on water qualityTask 3. Chemical experiment on water quality

Mazeikiu Merkelio Rackausko gimnazija

• Lithuania is one of a few European Lithuania is one of a few European countries where people use only countries where people use only groundwater for their basic needs.groundwater for their basic needs.

• The quality of drinkable water The quality of drinkable water depends on the composition of the depends on the composition of the soil and the depth of a borehole. In soil and the depth of a borehole. In Lithuania we use water from private Lithuania we use water from private wells (their depth is about 20 – 30 m) wells (their depth is about 20 – 30 m) or from waterhole boreholes (their or from waterhole boreholes (their depth is about 250 m).depth is about 250 m).

To test the quality of the water we To test the quality of the water we drink, our students decided to analyse drink, our students decided to analyse

6 types of drinkable water:6 types of drinkable water: • tap water,tap water,• well-water,well-water,• spring water,spring water,• filtrated water,filtrated water, • mineralized water,mineralized water, • ionisated water.ionisated water. to find such ions as ammonium, nitrate, nitrite, to find such ions as ammonium, nitrate, nitrite,

phosphate.phosphate.

• We were looking for these ions We were looking for these ions because they are known to cause a lot because they are known to cause a lot of serious health problems, even of serious health problems, even cancer. These ions appear in cancer. These ions appear in groundwater as a result of human groundwater as a result of human household activities (for example, the household activities (for example, the use of fertilizers). use of fertilizers).

• In addition to that, we also decided to In addition to that, we also decided to test the melted snow water and to test the melted snow water and to compare the results. compare the results.

For the chemical water For the chemical water analysis we used analysis we used Merck Compact Merck Compact laboratory for water laboratory for water testing. It consists of testing. It consists of reagents and reagents and accessories for the accessories for the determination of pH, determination of pH, electrical conductivity electrical conductivity (TDS), ammonium, (TDS), ammonium, nitrate, nitrite, nitrate, nitrite, phosphate. Most of phosphate. Most of the tests are based on the tests are based on colorimetric methodcolorimetric method..

Work ProcessWork Process

Determination of pH and Determination of pH and TDSTDS

• Pure water has a pH Pure water has a pH of 7. The pH range of 7. The pH range of 3 to 7 shows that of 3 to 7 shows that the water is weakly the water is weakly acidic, and the acidic, and the range of 7 to 11 range of 7 to 11 shows that it is shows that it is weakly alkaline. weakly alkaline.

• TDS of drinkable TDS of drinkable water has to be 0 – water has to be 0 – 1000 mg/l.1000 mg/l.

Determination of NitrateDetermination of Nitrate

Nitrate ions found in Nitrate ions found in drinkable water are drinkable water are dangerous for our dangerous for our health. What is more, health. What is more, in case of chemical in case of chemical reactions they can reactions they can change to nitrite ions. change to nitrite ions. The concentration limit The concentration limit is 50 mg/l of nitrate is 50 mg/l of nitrate ions for adults and 10 ions for adults and 10 mg/l for infants.mg/l for infants.

Determination of NitriteDetermination of Nitrite

Nitrite ions are in Nitrite ions are in particular particular dangerous as they dangerous as they may cause cancer. may cause cancer. The concentration The concentration limit of these ions limit of these ions is 0,5 mg/l for is 0,5 mg/l for adults and 0,02 adults and 0,02 mg/l for infants.mg/l for infants.

Determination of Determination of AmmoniumAmmonium

The concentration The concentration limit of ammonium limit of ammonium is 0,5 mg/l.is 0,5 mg/l.

Determination of Determination of PhosphatePhosphate The amount of The amount of

phosphate is not phosphate is not rationed. rationed. Phosphates are Phosphates are used for water used for water softening.softening.

ResultsResultsType of Type of waterwater

pHpH TDS, TDS, mg/lmg/l

Nitrate, Nitrate, mg/lmg/l

Nitrite, Nitrite, mg/lmg/l

AmmoniuAmmoniu

m, mg/lm, mg/l Phosphate, Phosphate,

mg/lmg/l

Tap waterTap water 66 420420 00 00 0,20,2 0,250,25

Well-waterWell-water 55 270270 1010 00 0,10,1 0,250,25

Spring Spring

waterwater 66 600600 00 00 0,10,1 00

Filtrated Filtrated

waterwater 5,55,5 1010 00 00 00 00

MineralizeMineralize

d waterd water 6,26,2 500500 00 00 0,10,1 00

Ionisated Ionisated

waterwater 7,87,8 290290 00 00 0,10,1 00

Melted Melted

snowsnow 55 2020 3030 00 0.30.3 0,250,25

ConclusionsConclusions• The pH of almost all sorts of the tested water is The pH of almost all sorts of the tested water is

weakly acidic. Only the weakly acidic. Only the ionisatedionisated water is neutral. water is neutral.• Total dissolved salts (TDS) are in the tolerated range.Total dissolved salts (TDS) are in the tolerated range. • The amount of nitrate ions in all kinds of the tested The amount of nitrate ions in all kinds of the tested

water is also in the acceptable range. However, we water is also in the acceptable range. However, we have found 10 mg/l of these ions in the well-water. have found 10 mg/l of these ions in the well-water. This amount of nitrate is dangerous for infants. And This amount of nitrate is dangerous for infants. And there were 30 mg/l of nitrate ions in the melted snow there were 30 mg/l of nitrate ions in the melted snow water (although it is also within the permitted water (although it is also within the permitted limits).limits).

• We haven’t found nitrite ions in any of the water We haven’t found nitrite ions in any of the water types.types.

• The amount of ammonium ions is normal in all kinds The amount of ammonium ions is normal in all kinds of the tested water.of the tested water.

As a result, we can state that all As a result, we can state that all the tested types of drinkable the tested types of drinkable water are suitable for drinking!water are suitable for drinking!

Thank you for your Thank you for your attentionattention

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