Paper 1 Questions Flashcards
Ammonium nitrate is produced from ammonia and nitric acid on a large scale in industry. Ammonium nitrate can also be made in the laboratory by titrating ammonia solution with dilute nitric acid.
Ammonium nitrate crystals can then be obtained by evaporating off some of the water from the solution.
Give two reasons why this laboratory method is not suitable for use on a large scale in industry. [2]
- volumes of solution too large for titration method (1)
- large volumes of liquid need to be heated and then allowed
to crystallise (1)
When there are alternative methods of producing a product, the final pathway is
chosen by considering atom economy, cost of energy, yield of product and rates
of reactions.
State another factor that should also be considered. [1]
equilibrium position/usefulness of by-products [1]
Give a reason why adding hydroxide ions to an acid solution leads to an increase in pH. [1]
hydroxide ions react with hydrogen ions and reduce the hydrogen ion concentration therefore increase pH (1)
Describe one similarity and one difference between the industrial production of ammonium sulfate and the laboratory preparation of ammonium sulfate. [2]
a similarity from :
- both use sulfuric acid (1)
- both (are examples of) neutralisation (1)
and a difference from :
- the industrial process is on a much
- larger scale than the laboratory process / ORA (1)
- the industrial process involves more stages than the laboratory process / ORA (1)
- ammonia is a gas in the industrial process but a solution in the laboratory process (1)
- laboratory preparation uses titration and crystallisation (1)
Explain why dilute hydrochloric acid is described as a strong acid [2]
an explanation linking
* fully dissociates (1)
* to form {H+/hydrogen} ions (1)
Calcium and potassium react with water in similar ways.
One similarity in the reactions is that hydrogen gas is produced.
State one other similarity in the products of the reactions of calcium and potassium with water. [1]
both form a hydroxide
After evaporation, the mass of the potassium chloride was determined.
The theoretical yield of the experiment was 0.70g.
The actual yield was 0.84g.
This gave a percentage yield greater than 100%.
State why the actual yield is greater than the theoretical yield [2]
{the salt/solid/potassium chloride} was still wet/ not all of the water had been evaporated off
Copper carbonate is added to the acid in the flask.
The copper carbonate is added one spatula measure at a time until the reaction has finished.
State two observations that would show the reaction has finished. [2]
Any TWO from
* no more bubbles / fizzing (1)
* no further change in colour (1)
* {solid / copper carbonate} remains at bottom of flask / no more {solid /copper carbonate} dissolves (1)
Calcium nitrate and calcium carbonate are both ionic compounds.
Calcium nitrate mixed with water behaves as an electrolyte.
Calcium carbonate mixed with water does not behave as an electrolyte.
Explain, in terms of solubility and movement of ions, this difference in behaviour (2)
- nitrate is soluble (1)
- carbon is insoluble (1)
- so ions free to move in solution (1)
When a solution of sodium sulfate is electrolysed, the products formed at the electrodes are hydrogen and oxygen. Explain why [4]
Hydrogen (H+) and sodium (Na+) ions are attracted to cathode, hydroxide (OH−) ions and sulfate (SO42−) ions are attracted to the anode; [1 mark]
Reason:
The ions are attracted to the oppositely charged electrode; [1 mark]
2 hydrogen ions / 2H+ accept 2e- to form a hydrogen molecule / H2; [1 mark]
4 hydroxide ions / 4OH− lose 4e- to form an oxygen molecule / O2; [1 mark]
[Total: 4 marks]
The following are the results obtained from an electrolysis experiment when copper sulfate solution was electrolysed for 10 minutes.
Anode: -0.81g change in mass
Cathode: +0.78g change in mass
Explain, in terms of ions, the changes in mass shown above. [3]
- at anode, copper / atoms {lose electrons/ oxidised} / (copper) ions leave anode (cause mass loss) [1]
- (copper) ions (in solution) move to the cathode [1]
- at cathode (copper) ions {gain electrons/ reduced} (-cause mass gain) [1]
Calcium nitrate and calcium carbonate are both ionic compounds
Calcium nitrate mixed with water behaves as an electrolyte.
Calcium carbonate mixed with water does not behave as an electrolyte.
Explain, in terms of solubility and movement of ions, this difference in behaviour. [2]
- (calcium) nitrate {is soluble/ dissolves}, (calcium) carbonate {is insoluble/ doesn’t dissolve}
- so ions {free to move in solution/ not free in solid}
In the electrolysis of sodium chloride solution, bubbles of a colourless gas form at the
cathode.
This gas, when mixed with air, burns with a squeaky pop.
Explain how this gas is formed at the cathode. [2]
- hydrogen ions attracted to cathode/ negatively charged electrode [1]
- (two) hydrogen ions {gain (two) electrons/ are reduced/ form hydrogen molecules}/ correct half equation [1]
State what could be added into the circuit to show a current is flowing during electrolysis. [1]
light bulb / ammeter/ lamp [1]
Explain how lubricating the chain with oil prevents corrosion of the steel chain. [2]
- {air/oxygen} excluded / {water/moisture} excluded / oil acts as a barrier (1)
- {air/oxygen} and {water/moisture/damp conditions} both needed (for iron to rust / corrosion) (1)
Excess solid nickel carbonate is added to dilute sulfuric acid in a beaker.
Nickel sulfate is formed in solution.
Describe how a sample of pure, dry nickel sulfate crystals can be obtained from the mixture of nickel sulfate solution and excess solid nickel carbonate in the beaker. [3]
- filter (1)
and two in a logical order from - crystallisation (1)
- heat solution (to concentrate) (1)
- allow to cool (1)
- dry crystals between filter papers (1)
Aluminium cannot be extracted by heating its oxide with carbon.
Aluminium has to be extracted from its oxide by electrolysis.
Explain why. [2]
- aluminium is high in reactivity / aluminium oxide is (very) stable (1)
- aluminium (oxide) cannot be reduced by carbon (1)
An experiment is planned to record the change in pH as a powdered base is added to 50cm3 of dilute hydrochloric acid. Explain why, in terms of particles present, the pH increases during the experiment. [2]
In terms of the particles present, the pH increases during the experiment because:
The hydrogen ions are reacted / neutralised
OR
H+ + OH– → H2O; [1 mark]
So, the concentration of hydrogen ions / H+ decreases
OR
So, the concentration of hydroxide ions / OH– increases; [1 mark]
In recent years, researchers have been investigating alternative methods of extracting metals from soils.
Researchers have found that growing certain plants in appropriate areas can result in the phytoextraction of copper.
Describe how growing plants can result in the phytoextraction of copper [2]
- plants absorb {copper/metal} (ions) from the {soil/ores} / plants concentrate copper ions (1)
- plants (harvested and) burned (to leave copper/metal compound) (1)
During an experiment, the pH of a solution changes from 2 to 10. If phenophthalein indicator is added at the beginning of the experiment, a colour change happens. State the colour change that occurs. [1]
Colourless to Pink [1]
State and Explain how the pH changes as the magnesium hydroxide is added to the dilute hydrochloric acid [4]
The pH changes as the magnesium hydroxide is added to the dilute hydrochloric acid by:
Increases pH; [1 mark]
Until pH above 7; [1 mark]
And an explanation linking:
REACTION
{Magnesium hydroxide / base / alkali / OH- ions} {reacts with / neutralises} {the acid / the H+ ions}; [1 mark]
IONS REMAINING
So the hydrogen ions concentration is reduced / all hydrogen ions reacted / there is an excess of hydroxide ions; [1 mark]
Using different reactants, a solution of copper sulfate was prepared
Describe what should be done to obtain copper sulfate crystals from this copper sulfate solution [2]
Heat solution (to evaporate water and concentrate the salt solution); [1 mark]
Leave to cool / in a warm place / on window sill / for several days; [1 mark]
Explain what is a weak acid [2]
- partially {dissociated / ionised} [1]
- { concentration of H+ ions lower / fewer H+ ions} than expected [1]
During an experiment, the pH of a solution changes from 2 to 10, as a base is added to an acid.
Explain, in terms of particles present, why the pH increases during the experiment. [2]
- {hydrogen ions/H+ ions}{reacted / neutralised} [1]
- {concentration falls/fewer} H+/{concentration rises/more} OH- [1]
