Flashcards
Water
Cards in this deck (11)
- 1water treatmentpotable water = water intended for human use/consumption
1. coagulation
2. flocculation
3. sedimentation
4. filtration
5. disinfection
6. storage - 2coagulation + flocculation- silicate clay particles are negatively charged which causes them to repel strongly + create suspension in water
- coagulants w highly-positive charge are added to neutralise silicates
coagulants attract silicate minerals into an insoluble floc that's removed by sedimentation + filtration - 3water chlorination- disinfects water by killing microorganisms
- chlorine + compounds that contain chlorine are powerful oxidisers that inhibit microorganism growth by reacting w important biological molecules - 4water chlorination equationsCl2 + H2O ⇌ HOCl + H3O+ + Cl-
HOCl + H2O ⇌ OCl- + H3O+ - 5effect of pH on chlorination equilibriumdecrease in pH (acidic) --> increases H3O+ --> shifts to left --> less HOCl
increase in pH (alkaline) --> decreases H3O+ --> shifts to right --> more HOCl - 6hard water- contains high conc. of dissolved minerals/salts (Mg2+ & Ca2+)
- reduces effectiveness of soap by neutralising charge of soap anion
- Mg2+ & Ca2+ react w soap to form insoluble precipitate (soap scum) - 7zeolites- negatively-charged aluminosilicate minerals w a highly porous structure (high SA:V)
- makes hard water softer via ion-exchange - 8water softener- 2 tanks
- 1 tank contains millions of zeolite beads w Na+ adsorbed to surface
- other tank contains concentrated NaCl solution
- hard water passes through pores of zeolite where Mg2+ and Ca2+ are exchanged for 2Na+
- concentrated brine solution is transferred periodically to 1st tank to replenish Na+ & remove Ca2+ and Mg2+ from zeolites - 9zeolite equations2Na+ (zeolite) + Mg2+ (aq) ⇌ 2Na+ (aq) + Mg2+ (zeolite)
2Na+ (aq) + Mg2+ (zeolite) ⇌ 2Na+ (zeolite) + Mg2+ (aq) - 10desalination- saline water is made potable by removing dissolved salts
thermal distillation = water's heated until it boils/turns to steam --> steam is condensed + pure water is recovered
reverse osmosis = water is forced under pressure through a semi-permeable membrane that removes impurities - 11disadvantages of desalination- development, construction, operation, + maintenance of desal plants are expensive
- uses large quantity of energy which is derived from non-renewable sources that contribute to global warming
- membrane pores can become clogged which requires cleaning w hazardous chemicals/replacement
- marine organisms can be killed during inflow of saline water from ocean
Information
- Description
- South Australian Certificate of Education Chemistry Flashcards on Water, created by Michala Baldwin on 31/10/2022.
- Created by
- Michala Baldwin
- Views
- 0
- Rating