Why is applying a base to acidic water an effective method to treat water?
Acid rain can change the overall pH of various bodies of water. This drop in pH can be harmful to the organisms that live in the water. Often times the acidic water can be treated by applying a base to the water. Exlpain why this is an effective method to treat the water.
Ideally, water has a pH of about 7 which is a neutral value (neither acidic nor basic). If water has a low pH (i.e. acidic), then it needs to be treated to bring it back to a neutral value. Acids and bases react to produce neutral solutions with the formation of a salt and water.
For example, hydrochloric acid and sodium hydroxide react as given below
HCl + NaOH --> NaCl + H2O
The reaction that occurs is called a neutralization reaction and results in a neutral solution. For water treatment, weaker bases such as sodium bicarbonate can be used as we don't want to add excessive amounts of base which would result in a solution that is basic instead of acidic. Frequent testing during the treatment process ensures that water reaches a neutral value.
Oxides of sulphur and nitrogen are like a pollutant in air, they get mixed with the vapours and get condensed hence fall in the form of acid. As it contains highly acidic chemicals like hydrogen sulphite, hydrogen sulphate, etc. It is very important to reduce their effect n this can be only done by adding base to the dilute chemical and making it NEUTRAL as to reduce further damage to AQUATIC LIFE...