Question

A water sample is not alkaline to phenolphthalein however 25ml of the sample on titration required 4.5ml , 0.02N HCL for methyl orange end point. Determine the types and amount of alkalinity present in the sample? (Find P&M, amount of alkalinity)

Answer 1

Moles of HCl used per litre of water sample

$=\frac{4.5}{1000}×0.02×\frac{1000}{25}$

$=0.0036$

Alkalinity (Mg of CaCO₃/L)

$=0.0036×100$

$=0.36$

$=360ppm$