Chapter 12, Problem 50E

Interpretation Introduction

Interpretation:

Whether the concentration of nitrates in water can be decreased by boiling, or not, is to be explained.

Concept Introduction:

Water gets polluted due to the presence of various biological and chemical contaminants in it. Biological contaminants include microorganisms such as Giardia, Legionella while chemical contaminants are mercury, lead, benzene, trichloroethylene etc. Both these render water unfit for consumption by human beings and animals, if the contaminant exceeds a certain limit, termed as Maximum Contaminant Limit.

The concentration of a contaminant is reported as the mass of contaminant (in milligrams) present in one liter of water.

Hard water is a solution of calcium and magnesium salts in water. Presence of calcium and magnesium ions makes water hard and renders it unusable for various purposes, such as cleaning clothes and utensils, bathing and in water heaters etc.

Boiling of water cannot get rid of contaminants because this decreases the total volume of the sample but the mass of the contaminant remains same. Moreover, the concentration of the contaminant increases.