1. Water Analysis

2. Instrumental techniques:
- pH meters
- atomic absorption spectroscopy
- calorimetry
Laboratory techniques:
- filtration
- evaporation
- titration

3. pH pH measures how acidic or alkaline a solution is
Measured on scale from 0-14
Acidic = pH < 7
Neutral = 7
Alkaline = pH > 7

4. Can use Universal Indicator to measure pH
Solution or paper that changes colour depending on pH and can be compared to a colour chart to get pH value
More accurate to use pH meter

5. pH meters

6. Meter = pair of electrodes to dip into solution, electronic circuit & reader
Electrodes develop a voltage between them that is dependent on H+ ion concentration
Transfers voltage through circuit to reader which displays pH value

7. Sensitive instruments that have to be calibrated regularly using buffer solution
Uses – analyse pollutants in water, pH rainwater, water treatment plants, titrations

8. Atomic absorption spectrometry(aas)
Measures concentration of heavy metals in water sample
Sample is dissolved and sprayed into spectrometer
Heated in flame converting it into the atoms it is composed of

9. Lamp made from the element being tested for generates light
Light passes through sample atoms and some is absorbed
Amount absorbed depends on amount of element present

10. Uses – detect and measure concentration of heavy metals in water sample

11. Atomic absorption spectrometer

12. Calorimetry
A calorimeter passes light through a sample solution and measures the amount of light it absorbs
The colour of this solution after absorbing the light is then compared to a number of different coloured solutions of known concentrations

13. The colour the sample solution matches tells us its concentration
The more concentrated the colour the more concentrated the solution
Uses – analysis of fertilisers & of lead in water

14. Suspended solids Cloudiness in water caused by suspended solids
They are insoluble solids that are too fine to sink to bottom of sample
Interferes with photosynthesis
Indicates sewage

15. Removed in treatment plant by flocculation and filtration
Calculate amount of suspended solids in p.p.m
Get amount in grams, convert amount to mg, 1mg = 1p.p.m

16. Dissolved solids Can effect colour or taste of water
High amount of dissolved solids indicates sample may be salt water
Can only be calculated by evaporation
Get amount in grams, convert amount to mg, 1mg = 1p.p.m

17. Hardness in water
Carry out a titration using edta (ethylenediaminetetraacetic acid)
Edta in burette and water sample in conical
Indicator = solochrome black
pH buffer of 10 has to be used as the edta only forms a complex with the Ca2+ ions at a pH above 9

18. BOD BOD = Biochemical oxygen demand
BOD of a water sample is the amount of dissolved oxygen used up in a sample that is left in the dark for 5 days at 20oC
Collect 2 samples, test one immediately, leave the other for the 5 days, test 2nd sample & calculate difference between them