Section 4: Physical Chemistry Flashcards
an acid has a pH of…
less than 7
an alkali has a pH of…
more than 7
a neutral substance has a pH of…
7
universal indicator turns what colour in the presence of an acid(weak-stronger-strongest)?
yellow-orange-red
universal indicator turns what colour in the presence of an alkali(weak-strong)?
blue-purple
universal indicator turns what colour in the presence of a neutral substance?
green
what colour is litmus paper in an acid?
red
what colour is litmus paper in an alkaline solution?
blue
what colour does litmus paper become in a neutral solution?
purple
what colour is phenolphthalein in an acid?
colourless
what colour is phenolphthalein in an alkali?
pink
what colour is methyl orange in an acid?
red
what colour is methyl orange in an alkali?
yellow
an acid is..
a source of hydrogen ions H+
a base is…
a substance that can neutralise an acid
an alkali is…
a soluble base. A source of hydroxide ions OH-
what is the name for the reaction between an acid and a base/alkali?
a neutralistion reaction
acid + base –>
salt + water
H+ + OH- –>
H2O
is metal oxide an example of a base or an acid?
a base
acid + metal oxide –>
salt + water
hydrochloric acid + metal oxide —>
metal chloride + water
sulfuric acid + metal oxide –>
metal sulfate + water
nitric acid + metal oxide –>
metal nitrate + water
acid + metal carbonate —>
salt + water + carbon dioxide
hydrochloric acid + metal carbonate –>
metal chloride + water + carbon dioxide
sulfuric acid + metal carbonate –>
metal sulphate + water + carbon dioxide
nitric acid + metal carbonate –>
metal nitrate + water + carbon dioxide
are sodium, potassium and ammonium salts soluble or insoluble?
soluble
are nitrates soluble or insoluble?
soluble
are most chlorides soluble or insoluble? what is the exception?
soluble, except for silver chloride
are most sulfates soluble or insoluble? what are the two exceptions?
soluble, except barium sulfate and calcium sulfate
are most carbonates soluble or insoluble? what are the 3 exceptions?
insoluble, except sodium, potassium and ammonium carbonates
what is the method for making soluble salts using acids and insoluble bases?
- Chose an acid and an insoluble base(e.g mostmetal oxides, metal carbonates, metal hydroxide) based on the salt you want to make 2. add the insoluble base to the acid - the solid will disolve in the acid as it reacts. When the acid is neutralised the excess solid will sunk to the bottom. 3. filter off the excess base to get the salt solution - for pure solid salt crystals evaporate off the water
what is the name of the method used to make a soluble salt using an alkali? what does it entail?
titration - you have to add exactly enough alkali to just neutralise the acid, using an indicator to show you when the reaction’s finished