C3.3 - spec Flashcards
loss of electrons is…
oxidation
gain of electrons is…
reduction
look at the reaction below:
aluminium + iron(III)oxide -> aluminium oxide + iron
identify which is the:
- oxidising agent
- reducing agent
- iron(III) oxide is the oxidising agent as it oxidises aluminium to aluminium oxide
- aluminium is the reducing agent as it reduces iron(III) oxide to iron
gain of oxygen is…
oxidation
loss of oxygen is…
reduction
look at the reaction below:
aluminium + iron(III)oxide -> aluminium oxide + iron
draw a half equation for
(a) the reactant being oxidised
(b) the reactant being reduced
(a) Al -> Al3+ + 3e- OXIDISED
(b) Fe3+ + 3e- -> Fe REDUCED
what kind of ions are formed when acids are dissolved in water?
hydrogen ions
what kind of ions are formed when alkalis dissolve in water?
hydroxide ions
describe neutralisation (in terms of its word equation)
acid + alkali/base -> salt + water
what is an aqueous neutralisation reaction?
in terms of ions
when hydrogen ions react with hydroxide ions to form water
how can you predict the salt made in a neutralisation reaction?
first part = name of metal in alkali
second part = acid used
write out the word equation for the following reaction:
copper(II) oxide + sulfuric acid
-> copper sulfate + water
NEUTRALISATION REACTION
so acid + base -> salt + water
what is a carbonate?
an ionic compound which contains a carbonate ion
write the word equation for when an acid and a carbonate react together
acid + carbonate -> salt + water + carbon dioxide
- carbon dioxide is produced as there is a CARBONATE present (self explanatory)
what is a fancy word for saying bubbling/fizzing?
effervescence
write the word equation for when an acid and a metal react together
acid + metal -> salt + hydrogen
explain what is meant by the term ‘dilute acid’
an acid which has a low ratio of acid to volume in a solution
ie. MORE WATER
explain what is meant by the term ‘concentrated acid’
an acid which contains a high ratio of acid to volume in a solution
ie. LESS WATER
explain the term ‘weak acid’
in terms of ionisation of ions
H+ ions are partially ionised (only a small fraction of their molecules release H+ ions)
explain the term ‘strong acid’
in terms of ionisation of ions
H+ ions are fully ionised (all molecules release H+ ions)
what happens (in terms of bonds), when an acid releases hydrogen ions (H+)?
- a covalent bond in the acid molecule breaks
- which produces a hydrogen ion + a negatively charged ion
how are relative acidity and alkalinity measured?
by pH
in terms of pH, how do you tell how strong an acid is?
the closer the pH value is to 0
in terms of pH, how do you tell how strong an alkali is?
the closer the pH value is to 14
what (in terms of ions) gives an acid a pH value closer to 0?
larger concentration of H+ ions
how does the pH value of a solution change if the hydrogen ion concentration increases by a factor of 10?
pH value decreases by 1
so what is the relation between hydrogen ion concentration and pH value of a solution?
hydrogen ion conc increases (factor of 10)
pH value decreases by 1
how do you measure the pH using a pH meter?
- wash pH probe with water
- put it in calibration buffer
- adjust reading to match pH of buffer solution
- wash the probe and place into solution to measure
- reecord reading on meter
advantages of a pH probe
exact pH value,
how does a universal indicator measure the pH of a solution?
changes colour, and then you compare it to the pH scale
