Zusammenfassung der Ressource
Acids and Alkalis
- Testing the pH of a
solution means using
an indictor
- The pH scale goes from 0 to 14
- The pH scale is a measure of how acidic or alkaline a solution is
- The strongest acid has pH 0
- The strongest alkali has pH 14
- A neutral substance has pH 7
- An indicator is just a dye that changes colour
- The dye changes colour depending on whether its above or below a certain pH
- Useful for estimating the pH of a solution
- Acids and Bases neutralise each other
- An acid is a substance with a pH of less than 7. Acids form H+ ions in water
- H+ is hydrogen
- A base is a substance with a pH of greater than 7
- An alkali is a base that dissolves in water. Alkalis form OH- ions in water.
- OH- is hydroxide
- The reaction between acids and bases
is called neutralisation
- acid + base to salt + water
- H + (aq) + OH- (aq) to H2O (l)
- State symbols tell you what physical state its in
- (s) is solid, (l) is liquid, (g) is gas, (aq) is dissolved in watter
- Acids Reacting with metals
- Metals react with acids to give salts
- Acid + Metal to Salt + Hydrogen
- The more reactive the metal the
faster the reaction will go very
reactive metals react explosively
- Copper does not react with dilute
acids at all because its less reactive
than hydrogen
- The speed of reaction is indicated by the rate at
which the bubbles of hydrogen are given off
- The hydrogen is confirmed by the
burning splint test giving the notorious
squeaky pop
- The name of the salt produced depends on which metal is used and which acid is used
- Hydrochloric acid will always produce chloride salts
- 2HCl + Mg to MgCl2 + H2 (magnesium chloride)
- 6HCl + 2Al to 2AlCl3 +3H2 (aluminium chloride)
- 2HCl + Zn to ZnCl2 + H2
- Sulfuric acid will always produce sulfate salts
- H2SO4 + Mg to MgSO4 + H2 ( magnesium chloride)
- 3H2SO4 + 2Al to Al2(SO4)3 + 3H2 (aluminium sulfate)
- H2SO4 + Zn to ZnSO4 + H2 (Zinc sulfate)
- Nitric acid produces nitrate salts when neutralised
- Nitric acid reacts with fine with alkalis to
produce nitrates but when reacted with
metals and produce nitrogen oxides
instead
- Oxides, Hydroxides and Ammonia
- Metal oxides and metal hydroxides are bases
- Some metal oxides and metal hydroxides dissolve in water. These soluble compounds are alkali
- even bases that wont dissolve in water will still react with acids
- Acid + Metal oxide to salt + water
- Acid + Metal hydroxide to salt + water
- The combination of metal and acid decides the salt
- hydrochloric acid + copper oxide to copper chloride + water
- hydrochloric acid + sodium hydroxide to sodium chloride + water
- sulfuric acid + zinc oxide to zinc sulphate + water
- sulfuric acid + calcium hydroxide to calcium sulphate + water
- Nitric acid + magnesium oxide to magnesium nitrate + water
- nitric acid + potassium hydroxide to potassium nitrate + water
- Ammonia can be neutralised with HNO3 to make fertiliser
- Ammonia dissolves in water to make an alkaline solution
- When it reacts with nitric acid you get a neutral salt
- Ammonia + nitric acid to Ammonium nitrate
- NH3 (aq) + HNO3 (aq) to NH4NO3 (aq)
- No water is produced
- Ammonium nitrate is an especially good
fertiliser because it has nitrogen from two
sources the ammonia and the nitric acid. Plants
need nitrogen to make proteins
- Making salts
- Making soluble salts using a metal or an insoluble base
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