12. DETERMINATION OF AMMONIA CONTENT IN GIVEN WATER SAMPLE

APPARATUS REQUIRED:

1. Measuring cylinder
2. Pipette
3. Conical flask
4. Spectrophotometer
5. Aluminum foil

THEORY:

Ammonia is naturally present in surface water, ground water and domestic sewage. Ammonia is largely produced by the deamination of organic nitrogen containing compounds and hydrolysis of curer.

Nessler’s method:

                  The method is based on the reaction between NH3 and HgI42– tetra-idomercury (TI) dnion in alkaline solution.

NH3+2HgI42–+3OH–—–>NH2Hg2IO+7I–+2H2o

PROCEDURE:

Firstly 25ml of water sample was taken. 1 ml of Nessler’s reagent was taken and 1 ml of Rochelle’s salt was added on it. Similar procedure was followed for the standard solution.

OBSERVATION TABLE:

Concentration (x)	Absorbance (y)
0.1	0.25
0.2	0.5
0.4	1
0.6	1.5
0.8	2.0
1.0	2.5

CALCULATION:

(x₁,y₁)= (0.3,0.75)

(x₂,y₂)= (0.7,1.75)

now,

y-y₁=(y₂-y₁/x₂-x₁) (x-x₁)

or,(y-0.75)= 1/0.4 (x-0.3)

or, 0.4y-0.3=x-0.3

or, y-0.75 = 2.5(x-0.3)

or, y=2.5x=0.75+0.75

=2.5x

Comparing with y=mx + c

m= 2.5

c= 0

The concentration of ammonia can be determined by 

y= mx + c

y= absorbance of water

c= constant

x= concn of ammonia

m= slop

Now, 

y= mx + c

1.236=2.5x+c

1.236= 2.5x

x= 1.236/2.5

x= 0.4444 mg/c

The absorbance (y) was found 0.645 in Saraswati water tap,

y=mx+c

Or, 0.645=2.5x+0

Or, 2.5x=0.645

x=0258 mg/c

CONCLUSION:

The concentration of ammonia on botanical ponds and Saraswati sadan tap water might be suitable for fish and drinking respectively because they are in low concentration.