Chapter 28- Water Flashcards
Electrolysis
The splitting of water
- add a little but of dilute sulfuric acid to water
- Hoffman apparatus (two upside down test tubes w/ wires in them, connected to battery)
- gas builds up, one twice more than the other (H) (the other is O)
Expansion of water
Substances-expand when heated
-contract when cooked
Water -expands over 4°, shrinks to 4°
-if cooled further, it expands again!
Meniscus
- water clings to glass
- when in a narrow container, the sides cling
- curved lens surface at the top of the water is called the meniscus
Desalation
To remove salt from seawater
House w glass roof
Pool of water w black bottom
Water evaporates
Condenses on glass, drips to the side and falls into pits at the side of the pool
Properties of water
- freezing point 4°
- boiling point 100°
- excellent solvent
- colourless,odourless liquid
Experiment to prove:
The presence of dissolved substances in a water source
Filter insoluble solids using paper and funnel
Pour filtered water onto clock glass(evaporation dish)
Put on beaker full of boiling water on hot plate ->
Water will evaporate->
Leaves residue
Rhyme for remembering the processes carried out to filter water
Silly Sean follows Chelsea football
What is screening
Water is passed through a wire mesh
Removes leaves/ litter etc.
What is settling
Aluminium sulfate added to water
Smal, insoluble particles come together +settle at the bottom of tanks
Filtration
Water is passed through beds of sand
Silvers small insoluble particles
Clear water but still contains bacteria
Chlorination
Kills bacteria in water
Carefully monitored
Fluoridation
Prevents tooth decay 🙃
Tests for water
Cobalt Chloride (blue-> pink) Anyhydrous copper sulfate (white -> blue)
