Oceanography

3. Procedure

To 50ml of water sample taken in a conical flask 5 ml of 0.025 M HCL is added. The sample is boiled for 5 minutes and cooled to ambient temperature. The sample is then titrated with 0.02M NaOH using 2-4 drops of Bromothymol blue as indicator. During cooling and titration CO₂ free air is bubbled through the sample. The alkalinity of the sample is calculated using the following formula;

Alkalinity = 1000 V_HCL x t _HCL x 1000 V _NaOH x t _NaOH

(milli mol/l) V_b V_b

Where,

t= molarity of HCL and NaOH

V= amount of HCL and NaOH in ml

V_b = volume of Sample in ml.