Chlorides are estimated by titration with a standard silver nitrate solution by using _______as indicator.
Explanation: 2-3 drops of potassium chromate are added to appropriate amount of water sample and then it is titrated with a standard solution of silver nitrate.
State whether the following statement is True or False.
Carbonate hardness can be removed by adding lime to water.
Explanation: Carbonate hardness is due to the presence of carbonates and bicarbonates of calcium and magnesium in water and can be removed by boiling or by adding lime to it.
Which of the following statement is wrong regarding permanent hardness?
Explanation: Permanent hardness is called non-carbonate hardness whereas temporary hardness is called carbonate hardness.
One degree of hardness is equivalent to ___ ppm
Explanation: Water is said to have one degree of hardness when its soap destroying power is equivalent to the effect of 14.25mg of calcium carbonate in one litre of water.
What can be filled in place of the question mark in the above table?
Explanation: When the degree of hardness is 9, then it indicates the hard water. For excessive hard water, it is 15 and for very hard water, it is 11.
In which method of determining total hardness of water is based on the premise that hardness producing substance react with soap and form insoluble compounds before lather is produced?
Explanation: In Clark’s method, total hardness is found by determining the standard soap solution required to obtain permanent lather with the water sample of known volume.
What is the indicator used in EDTA method?
Explanation: Hardness is determined by using Ethylene diamine tetra-acetic acid using Erio chrome, black T as indicator at a pH between 8.5 and 11.
The permissible limit of pH preferred for potable water is ___ppm.
The permissible limit of pH for potable water should not exceed 9 and should not be less than 6.5 and the preferred limit is 7-8.5.
Given list 1 and list 2, find which of the following pair is correctly matched?
Explanation: Lead has a permissible limit of 0.05ppm, phenol has 0.001ppm, zinc has 5ppm and chromium has a permissible limit of 0.05ppm in water.
What is the concentration of H+ ions in moles/L in water if the pOH value is 6?
Explanation: pH + pOH = 14
pOH = 6, so pH = 14-6= 8
H+ = 10-pH = 10-8moles/L.