C5 - Chemical Changes
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Acid + metal ->
salt + hydrogen
Acid + metal oxide ->
salt + water
Acid + metal carbonate ->
salt + carbon dioxide + water
Acid + metal hydroxide ->
salt + water
Acid + base ->
salt + water
Acid + alkali ->
salt + water
D. Alkali?
A substance that has a pH value of more then 7
RQ. Method for titration? (6)
• measure out vol. of alkali using bulb pipette (25cm3) • put alkali into conical flask • place acid in burette • add indicator (Phenolphthalein/ methyl orange) to alkali • add acid dropwise into flask unto neutralises (swirl) • repeat to get precise results
RQ. Safety measures for titrations? (2)
• goggles - fill burette below face-height/on the floor
RQ. Method for making a salt?
[ for v. reactive element ] • Titration • heat neutral solution in evaporating dish until half is evaporated • let cool • remove crystals and dry
What method should you use for making a salt from… • a non reactive metal • a metal of medium reactivity
• combine metal and acid - use metal hydroxide
Ionic equation for neutralisation?
H+(aq)+OH-(aq) -> H2O(l)
D. Base?
• Substance that neutralise acids (the oxide, hydroxide or carbonate of a metal that reacts with an acid and forms as salt as one of its products
What ions are bases acceptors of?
H+ ions / proton acceptors
What is a base that dissolves in water called?
an alkali
What are acids donors of?
protons / H+ ion
D. Acid?
Substances that dissolve in water, and the solution then has a pH of <7
What is formed when an acid dissolves in water?
H+ ions and a negative ion
You can use pH curves to….
find the volume of acid that neutralises the alkali in a titration