uses, reactivity and extraction of metals (topic 4) Flashcards
state how oxygen can be removed from zinc oxide to make zinc (2)
- reduction with carbon
- electrolysis
predict the method of extraction used to obtain calcium from its ore and explain your answer (2)
- electrolysis
- because calcium is more reactive than aluminium and carbon
(4)
- measure temperature change
- when each metal is added to silver nitrate solution
- same concentration / volume of solution (or same mass / moles of metal)
- the greater the temperature change the more reactive
(6)
general remarks:
- carbon and iron are the cheapest reactants
- hydrogen is the most expensive reactant
- separating solid products is expensive
- separating solid products is time consuming
method 1:
- tungsten needs to be separated from tungsten carbide
- some tungsten is lost as tungsten carbide
- the carbon dioxide produced will escape
method 2:
- the water vapour produced will escape
- no separation of solids is needed
method 3:
- tungsten needs to be separated from iron oxide
give the balanced symbol equation for the reaction of magnesium burning in air, and name the product of the reaction
the reaction has a high activation energy
(product is magnesium oxide)
magnesium hydroxide
what kind of substance is magnesium hydroxide
alkali
(1)
magnesium is more reactive than copper
what is the meaning of the term ‘ore’ (1)
rock that contains enough metal to make it economical to extract
what type of chemical reaction produces the iron in the blast furnace (1)
reduction
in the blast furnace, iron oxide reacts with carbon to produce iron and carbon dioxide, write a balanced symbol equation for this reaction
(originally Fe2O3 + C -> Fe + CO2)
(3)
- in pure iron all the atoms are the same size and are able to slide over each other
- in cast iron different sized atoms disrupt the structure
- so it is difficult for layers of atoms to slide over each other
explain the environmental problem that would result from the escape of the gas product from this reaction into the atmosphere (2)
- sulfur dioxide
- causes acid rain
- consequence of acid rain, such as ‘kills fish’, ‘kills plants’
in the second stage, copper oxide, CuO, is reduced using carbon, describe and explain what happens during this reaction (3)
- heat copper oxide with carbon
- oxygen is removed by carbon
- because carbon is more reactive than copper
some people believe that recycling copper may be better than extracting copper from its ores, explain the advantages and disadvantages of recycling copper instead of extracting it from its ores (4)
for recycling (max 2 marks):
- less acid rain pollution
- copper reserves last longer
- energy for extraction is saved
- less mining
- less waste of copper
against recycling (max 2 marks):
- collection problems
- transport problems
- difficult to separate copper from appliances
- energy used to melt the collected copper
iron oxide + carbon monoxide ➔ iron + carbon dioxide
(3)
- heating with hot air
- coke reacts with O2
- CO reacts with the ore
(2)
yes, because:
- magnesium had the most bubbles and the largest temperature increase
- copper had no bubbles and there was no temperature increase
- the increase in temperature and the number of bubbles produced go up with the metal reactivity
suggest one way of improving the method to give results which are more repeatable (1)
use the same mass of metal
- the grey crystals are silver
- the copper ions produced are blue
- because copper displaces silver
(5)
method (max 3 marks):
- add the metals to dilute hydrochloric acid and measure the temperature change (or compare rate of bubbling or compare colour of resulting solution)
- no reaction for copper as shown by:
- no temperature change (or no bubbles)
- for magnesium and iron:
- magnesium increases in temperature more than iron (or magnesium bubbles faster than iron or magnesium forms a colourless solution and iron forms a coloured solution)
control variables (max 2 marks):
- same concentration of hydrochloric acid
- same volume of hydrochloric acid
- same mass of metal
- same moles of metal
- same particle size of metal
- same temperature of acid (if comparing rate of bubbling)
brown
give the ionic equation for the reaction of chlorine with potassium iodide
explain why the reaction between chlorine atoms and iodide ions is both oxidation and reduction (2)
- iodide ions are oxidised because they lose electrons
- chlorine atoms are reduced because they gain electrons
write the balanced symbol equation for the reaction between iron and copper sulfate
write the ionic equation for the reaction between magnesium and copper sulfate
why is copper described as being reduced in these reactions
copper gains two electrons
describe a method to find the position of an unknown metal in this reactivity series using a dilute acid, your method should give valid results (5)
method (max 3 marks):
- add all the metals to an acid
- measure temperature change
- place the metals in order of temperature change
control variable (max 2 marks):
- same volume of acid
- same concentration of acid
- same initial temperature of acid
- same mass / moles of metal
use the students results to place copper, iron, magnesium, tin and zinc in order of their reactivity, from most reactive to least reactive
magnesium > zinc > iron > tin > copper
