Determination of PH of water by electromeric method
AIM:
To determine the PH of water by electromeric method.
PRINCIPLE:
This is electromeric method for determining PH in which the PH probe containing outer and inner electrodes.in outer electrode,the silver chloride wire immersed in neutral solution of potassium chloride called reference electrode.inner electrode contains same silver chloride wire in neutral potassium chloride solution called measuring electrode.glass bulb of electrode is the measuring part that is coated by silica gel which not allow hydronium ions to inside electrode.when the electrode is dipped in solution,hydronium ions from this solution is adhere to the glass bulb of electrode.the PH meter measure the difference between the outer solution with inner electrode solution and showing the result.
APPARATUS REQUIRED:
1)PH meter.
2)Beakers.
3)PH probe.
4)Reagent grade water (distilled water or millipore water).
CHEMICALS REQUIRED:
1)Potassium hydrogen phthalate.
2)Potassium dihydrogen phosphate.
3)Disodium hydrogen phosphate.
4)Sodium borate decahydrate.
Determination of total hardness in water
BUFFERS AND PREPARATIONS:
Why we should calibrate the PH meter by PH buffers?
Meaning of the buffer is not changing in its PH value.if the PH meter shows buffer PH correct,the sample value also be correct.if buffer value wrong,sample value be also wrong.we cannot use sample as buffers.buffers can be prepared by some chemicals which are not change the PH of it.
1)PH 4.00 buffer
Dissolve 10.12g of potassium hydrogen phthalate in 1000ml reagent grade water.
2)PH 7.41 buffer:
Dissolve 1.179g of potassium dihydrogen phosphate and 4.303g of disodium hydrogen phosphate in 1000ml reagent grade water.
3)PH 9.18 buffer:
Dissolve 3.80g of sodium borate decahydrate in 1000ml reagent grade water.
PROCEDURE:
Set the room temperature in which you want to determine the PH.turn on PH meter and let it for 10 minutes to warm up.wash the PH probe gently with distilled water.then place the PH probe in breaker containg distilled water.PH of distilled water at 25 degree Celsius will be 5.75 - 5.80.after the buffer solutions attains room temperature,place PH probe in to PH buffer 7.41.tolerence of each PH buffer is plus or minus 0.05.so for all PH 7.41 buffer,7.37 to 7.46 is acceptable.if not showing this PH value in PH meter,then adjust the value to 7.41 in frent side screw of PH meter.now wash the PH probe and dip in the PH buffer 4.00.adjust the PH value to acceptable by the back side screw of PH meter.then wash probe with distilled water and dip in the sample.if the PH of sample between 7.41 and 9.18.then calibrate the PH meter by PH 7.41 and 9.18 buffers.check the standard buffers between samples to recalibrate.
Determination of calcium and magnesium in water
Determination of electrical conductivity by conductivity cell method
AIM:
To determine the electrical conductivity of water by conductivity cell method.
PRINCIPLE:
Conductivity is a measure of dissolved positive and negative ions that conducting current.the conductivity electrode contains primary cell and secondary cell.the positive and negative ions attracting between these two cells per centimeter and value measured by EC meter.
APPARATUS REQUIRED:
1)EC meter (Electircal conductivity meter)
2)Beakers
3) Conductivity cell
4)Reagent grade water (distilled water or millipore water)
CHEMICALS REQUIRED:
1)Potassium chloride.
Determination of Chloride in water.
BUFFER AND PREPARATION:
1412 micro Siemens per centimetre:
Dissolve 745.9mg of anhydrous potassium chloride in 1000ml reagent grade water.store at 25 degree Celsius.
PROCEDURE:
Turn on the EC meter and let it for 10 minutes to warm up.wash the conductivity cell by distilled water and dip to beaker containing distilled water.after the EC buffer attaining the room temperature,dip the conductivity cell in buffer.tolerence is 1%.adjust the EC value to acceptable.now the EC meter is ready for sample testing.check the standard buffer between the samples.
FACTOR AFFECTING PH METER:
Temperature:
Check the PH at constant temperature for every time.difference in temperature cause change in PH and wrong result.
Conditions:
Store the buffers in refridgerator otherwise the solution will evaporate at high temperatures and change in PH.
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