C5 - chemical changes Flashcards
what are ores
rocks from which it is economical to extract the metals they have
what happens to many metals in ores
they become oxidised
how do you extract metals from oxides
reduce (remove the oxygen) the metal oxides
what is the reactivity series
a list of metals in order of their reactivity with most reactive at the top and least at the bottom
what are the two ways metal reactivity is ordered
reaction with water
reaction with a dilute acid (when reaction with water is slow)
what is the full reactivity series
potassium
sodium
lithium
calcium
magnesium
aluminium
(carbon)
zinc
iron
tin
lead
(hydrogen)
copper
silver
gold
how do potassium, sodium, lithium, and calcium react with water
fizz, give off hydrogen gas, leave an alkaline solution of metal hydroxide
how do magnesium, aluminium, zinc and iron react with water
very slow reaction
how do tin and lead react with water
slight reaction with steam
how do copper silver and gold react with water
no reaction at all
how do potassium sodium and lithium react with dilute acid
explode
how do calcium magnesium aluminium zinc tin and iron react with dilute acid
fizz
give off hydrogen gas
form a salt
how do tin and lead react with dilute acid
react slowly with warm acid
how do copper silver and gold react with dilute acid
no reaction
define a displacement reaction
a more reactive metal will displace a less reactive metal from an aqueous solution of one of its salts
what does an ionic equation show
only the atoms and ions that change in a reaction
what is oxidation
the loss of electrons
what is reduction
the gain of electrons
what does extracting a metal depend on
how easy it is to extract
how much metal the ore contains
the changing demands for the particular metal
why do we often use carbon to extract some metal oxides
it is more reactive than the metals
what is the word equation for the reaction of carbon with a metal oxide
metal oxide + carbon -> metal + carbon dioxide
why is gold often found in its native state
because it’s incredibly unreactive
how are metals extracted that are more reactive than carbon
by electrolysis of their molten metal compound
what is a salt
a compound formed when the hydrogen atom is wholly or partially replaced by metal (or ammonium) ions
what is the word equation for the production of salts
metal + acid -> salt + hydrogen
why are alkali metals never added to acid
the reaction would be too violent to be carried out safely
what salts are formed when you react a metal with HYDROCHLORIC ACID
chlorides (containing Cl- ions)
what salts are formed when you react a metal with SULFURIC ACID
sulfates (containing SO4^2- ions)
what salts are formed when you react a metal with NITRIC ACID
nitrates (containing NO3- ions)
what is a redox reaction
a reaction where both oxidation and reduction take place
how is the reaction between a metal and an acid a redox reaction
metal ions lose electrons (oxidised)
hydrogen ions from acid gain electrons (reduced)
what are bases
compounds that can neutralise acids
what is the word equation for neutralisation
acid + base -> salt + water
what do the sum of charges on ions in a salt add up to
0
how would you collect a pure dry sample of crystals of a salt
carry out titration with indicator
run that volume of acid into solution but without indicator
crystallise and dry the crystals of the salt
what is the word equation for the reaction of an acid with a carbonate
acid + carbonate -> salt + water + carbon dioxide
what are soluble hydroxides called
alkalis
what are bases
substances that can neutralise acids
what colour do alkalis go (using a universal indicator)
blue-purple
what colour do acids go (using a universal indicator)
red-yellow
what are carboxylic acids
weak acids
what is hydrochloric acid
a strong acid
what happens to hydrogen ion concentration when ph decreases by one unit
the hydrogen ion concentration increases by a factor of 10 (one order of magnitude)
