Chemistry Flashcards
What substances can we use to neutralise acids?
Metal oxides
( acid+metal oxide ~> salt+ water)
Metal hydroxides
( acid+metal hydroxide ~> salt water)
metal carbonates
( acid+metal carbonate~> salt water)
In the case of an acid spill how could you take take care of it?
By diluting it with water or neutralising it with an alkali.
The salt formed in a neutralisation depends on the acid. Name the 3 acids and what salts they produce:
Sulfuric acid - Sulfate salts
Nitric acids - Nitrate salts
Hydrochloric acids - Chloride salts
In some reactions, compounds are decomposed to form new compounds. What are 2 ways to decompose some compounds?
Thermal decomposition- uses heat
Electrolysis - uses electricity
What is the most common dissolved substance in seawater?
Sodium chloride ( common salt )
What happens if a direct current is passed through sea water?
Chloride gas is produced at one of the electrodes.
Name 6 uses of chlorine:
Solvents Bleach to kill bacteria ie. Toilets Pesticides and weed killers Hydrochloric acid Antiseptics and disinfectants Killing bacteria in swimming pools and drinking water
Explain oxidation and reduction:
Oxidation is the addition of oxygen to a substance.
Reduction is the removal of oxygen from a substance.
How is iron obtained?
By removing oxygen from iron oxide by heating with carbon:
Iron oxide+carbon~> iron+carbon dioxide
How is aluminium obtained?
By the removal of oxygen from aluminium oxide by electrolysis. The aluminium oxide is reduced to Al.
The corrosion of iron is called what?
Rusting
When does corrosion happen?
When the surface of a metal changes by reaction with oxygen - sometimes with water as well.
The more reactive the metal…
The less reactive the metal…
…The faster it corrodes
…The slower it corrodes
Low reactive metals are more resistant to what?
Oxidation and corrosion
An example of a metal that doesn’t corrode at all:
Gold
Why doesn’t reactive aluminium corrode as much as expected ?
Because it’s surface oxidises quickly to form a protective layer of aluminium oxide ( Al2O3) this stops any further corrosion.
Name 5 useful properties of metals:
Shiny when polished Conduct heat Malleable|can be hammered into shape Ductile|can be stretched into wires Conduct electricity
Properties of aluminium:
- low density/ light
- does not corrode because it has a layer if Al oxide that firms quickly on the surface
- uses with other metals to make planes
- many cars have bodies containing a lot of Al to reduce their weighting
Give a reason why cutlery is not made of pure iron.
Because pure iron rusts as it reacts with oxygen
What is dangerous about too much chlorine in a factory?
Breathing in to much chlorine can effect the insides of you body
Chlorine gas is toxic
What is the name of naturally occurring substances which metals are extracted?
Ores
