Acids, Bases and Salts Flashcards
what colour is produced by litmus paper when in acidic solution?
red
what colour is methyl orange in alkali?
yellow
what colour is phenolphthalein in acid?
colourless
what colour is methyl orange in acid?
red
what colour is litmus paper in alkali?
blue
what colour is phenolphthalein in alkaline?
pink
what colour is a universal indicator in acid?
red
what colour is universal indicator in alkaline?
blue
what is the word equation for metals reacting with acid?
metal + acid ⇒ salt + hydrogen
what is the word equation for acids reacting with bases?
acid + base ⇒ salt + water
what does hydrochloric acid form?
chloride
what does nitric acid form?
nitrate
what does sulphuric acid form?
sulphate
what is the word equation for acid reacting with metal oxide?
acid + metal oxide ⇒ salt + water
what is the word equation for acid and metal hydroxide reacting together?
acid + metal hydroxide ⇒ salt + water
what is the word equation for acid reacting with metal carbonate?
acid + metal carbonate ⇒ salt + water + carbon dioxide
describe how to prepare salts from neutralisation reactions ( i.e. dilute acid reacting with excess metal oxide or metal carbonate)
It can also be seen in terms of H+ and OH-
acid + base => salt + water
H+ (aq) + OH-(aq) => H2O (l)
explain how to carry out an acid-alkali titration
Method
- Use the pipette and pipette filler to add 25 cm3 of alkali to a clean conical flask.
- Add a few drops of an indicator and put the conical flask on a white tile (so you can see the colour of the indicator more easily).
- Fill the burette with acid and note the starting volume.
- Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
- Stop adding the acid when the end-point is reached (the appropriate colour change in the indicator happens). Note the final volume reading.
- Repeat steps 1 to 5 until you get consistent readings
- The same method works for adding an alkali to an acid - just swap around the liquids that go into the conical flask and burette.
what is an acid?
a substance that produces hydrogen ions ( H+) when dissolved in water
what is a base?
bases are substances that react with acids and neutralises them
explain the term weak and strong, as applied to acids
Strong acids
In aqueous solution, a strong acid is one that completely dissociates (splits up) into ions.
Example: hydrochloric acid.
HCl(g) + H2O(l)→H+(aq) + Cl-(aq)
This is not a reversible reaction, and 100% of the HCl molecules dissociate into ions.
Other strong acids include nitric acid and sulphuric acid.
Weak acids
In aqueous solution, a weak acid is one that only partially dissociates into ions. As a result, a state of equilibrium is produced.
explain the term weak and strong, as applied to bases
Strong bases
In aqueous solution, a strong base is one that completely ionises.
Example: sodium hydroxide.
NaOH(s) + H2O(l)→Na+(aq) + OH-(aq)
This is not a reversible reaction, and 100% of the NaOH(s) splits into free ions.
Weak bases
In aqueous solution, a weak base is one that only partially ionises. Just as with weak acids, a state of equilibrium is produced.
hydrochloric acid + sodium carbonate => sodium chloride + water + carbon dioxide (add metal carbonates to give salt + water + carbon dioxide)
2HCl + Na2CO3 => 2NaCl + H2O + CO2
sulfuric acid + calcium carbonate => calcium sulfate + water + carbon dioxide
H2SO4 + CaCO3 => CaSO4 + H2O + CO2
