Definitions Flashcards
What is hard water?
2
Hard water is water that will not easily form a lather with soap.
Hardness in water is caused by Ca^2+ or Mg^2+ ions dissolved in the water
What is temporary hardness?
Temporary hardness is hardness that can not be removed by boiling the water
What is permanent hardness?
Permanent hardness is hardness which cannot be removed by boiling the water
What is the total hardness of water?
Total hardness of water = calcium hardness + magnesium hardness
What is a complexometric titration?
A complexometric titration is a titration involving the formation of a complex between metal ions and a reagent such as edta.
In this type of titration the end point is marked by a sharp decrease in the concentration of free metal ions
What is a buffer solution?
A buffer solution is a polution that resists changes in pH, i.e. it keeps the pH constant
What is flocculation?
Flocculation is the coming together (coagulating) of small suspended particles in water
What is a flocculating agent?
A flocculating agent is a chemical added to water to coagulate suspended particles and thus help sedimentation to take place
Define biochemical oxygen demand (BOD)
The amount of dissolved oxygen consumed by biological (biochemical) action when a sample of water is kept at 20 degrees in the dark for five days
What is eutrophication?
Eutrophication is the enrichment of water with nutrients, leading to excessive growth of algae and other plants
What is primary treatment of sewage?
Primary treatment of sewage is a mechanical process in which large solids are removed by screening and some suspended solids are removed by settlement (sedimentation)
What is secondary treatment of sewage?
Secondary treatment of sewage is a biological oxidation process in which the levels of suspended and dissolved organic materials are reduced, i.e. the sewage is decomposed by means of bacteria which use the nutrients from the sewage together with oxygen from the air to break down the sewage
What is the tertiary treatment of sewage?
Tertiary treatment of sewage is a process involving the removal of phosphorus compounds by precipitation and the removal of nitrogen compounds by biological and ion-exchange methods
What is the principle of colorimetry?
The principle of colorimetry is that the amount of absorbance of light by a coloured solution is proportional to the concentration of the solution
