2. Inorganic ChemistryEdexcel IGCSE Chemistry: Topic test

20 questions, 54 marks

Edexcel IGCSE Chemistry

2. Inorganic Chemistry topic test

Total 54 marks

Name

Class

Date

1
A pupil investigates the reactivity of Group 1 metals using a data-logging pH probe: a same-sized piece of lithium is added to a large excess of water in a beaker, and the pH of the solution is monitored over time until it stabilises; the experiment is then repeated separately with a same-sized piece of potassium.
(a)
In the experiment, the pH of the water increases more quickly, and reaches a higher final value, for potassium than for lithium. What does this show about the relative reactivity of potassium and lithium with water?
[1 mark]
APotassium is less reactive than lithium
BPotassium is more reactive than lithium, since it produces hydroxide ions (raising the pH) more quickly
CLithium is more reactive than potassium
DPotassium and lithium are equally reactive with water
(b)
The reaction between an alkali metal and water is 2M + 2H2O → 2MOH + H2, where M represents the alkali metal. Which gas is produced, and how could this be confirmed?
[1 mark]
AOxygen gas; it relights a glowing splint
BCarbon dioxide gas; it turns limewater cloudy
CHydrogen gas; it produces a squeaky pop with a lit splint
DChlorine gas; it bleaches damp litmus paper
(c)
Write a balanced symbol equation, including state symbols, for the reaction between potassium and water, and explain in terms of electronic configuration why potassium reacts faster than lithium.
[2 marks]
Total for question 1: 4 marks
2
A technician is given three sealed gas jars, one containing chlorine gas, one containing bromine vapour, and one containing iodine vapour, and is asked to identify each one by its colour and physical state at room temperature, before predicting how a sample of fluorine, which lies above chlorine in Group 7, would compare in reactivity and boiling point.
(a)
Based on typical trends in Group 7, in which physical state would bromine be found at room temperature?
[1 mark]
ASolid
BLiquid
CGas
DPlasma
(b)
Predicting the properties of fluorine, which lies above chlorine in Group 7, which statement is correct?
[1 mark]
AFluorine is less reactive than chlorine and has a lower boiling point
BFluorine is less reactive than chlorine and has a higher boiling point
CFluorine is more reactive than chlorine and has a lower boiling point
DFluorine is more reactive than chlorine and has a higher boiling point
(c)
Explain, in terms of electronic configuration, why fluorine is more reactive than chlorine, even though both are in Group 7.
[2 marks]
Total for question 2: 4 marks
3
A student burns excess white phosphorus in a sealed glass syringe apparatus containing 100 cm3 of air, allowing the resulting white smoke (phosphorus pentoxide, P4O10) to dissolve into a small amount of water present in the apparatus, and then leaves the apparatus to cool to room temperature before measuring the final volume of gas remaining.
(a)
The volume of gas remaining after the experiment is 79 cm3. Calculate the percentage, by volume, of oxygen that was present in the original 100 cm3 sample of air, and identify which gas makes up most of the 79 cm3 of gas remaining.
[3 marks]
(b)
Explain why it is important that excess phosphorus is used in this experiment, and explain why the volume of gas is measured only after the apparatus has cooled back down to room temperature.
[4 marks]
Total for question 3: 7 marks
4
A student compares the industrial extraction of zinc, obtained by reducing zinc oxide with carbon in a furnace, with the extraction of sodium, which must be obtained by the electrolysis of molten sodium chloride, and investigates why these two metals need different extraction methods, even though sodium is much less dense and more reactive than zinc.
(a)
Explain why zinc oxide can be reduced to zinc metal by heating with carbon, but sodium chloride cannot be reduced to sodium metal in the same way, referring to the positions of carbon, zinc and sodium in the reactivity series.
[6 marks]
(b)
During the electrolysis of molten sodium chloride, write the half-equation for the reaction that occurs at the cathode to form sodium metal, explain in terms of electron transfer why this is classified as reduction, and explain why this method could not be used to extract sodium from solid (unmelted) sodium chloride.
[6 marks]
Total for question 4: 12 marks
5
A gardener tests the pH of soil samples from three different flower beds using universal indicator solution, obtaining colours that correspond to pH 4, pH 7 and pH 10, and wants to know which beds are most suitable for a plant that grows best in weakly acidic soil.
(a)
Which of the three soil samples described has a pH that falls in the range described as 'weakly acidic'?
[1 mark]
AThe pH 4 sample
BThe pH 7 sample
CThe pH 10 sample
DNone of the samples
(b)
Which piece of laboratory equipment would allow the gardener to measure the pH of a soil sample most precisely, rather than only an approximate pH?
[1 mark]
ALitmus paper
BPhenolphthalein indicator
CMethyl orange indicator
DA calibrated pH probe/meter
(c)
State what is meant by the term pH, and explain what the pH values found for the three soil samples show about the relative concentrations of hydrogen ions and hydroxide ions present in each one.
[2 marks]
Total for question 5: 4 marks
6
A student prepares a sample of insoluble lead(II) iodide by mixing a solution of lead(II) nitrate with a solution of potassium iodide, producing a bright yellow precipitate, which is then filtered, washed and dried.
(a)
What type of reaction produces the yellow precipitate of lead(II) iodide in this experiment?
[1 mark]
APrecipitation
BNeutralisation
CThermal decomposition
DCombustion
(b)
Which technique should the student use to separate the solid lead(II) iodide precipitate from the remaining solution?
[1 mark]
ASimple distillation
BCrystallisation
CChromatography
DFiltration
(c)
Write the balanced ionic equation for the precipitation reaction that forms lead(II) iodide, and explain why potassium nitrate remains dissolved in the solution rather than being precipitated.
[2 marks]
Total for question 6: 4 marks
7
A technician is given an unlabelled white solid and is told it is one of four possible compounds: sodium chloride, sodium sulfate, sodium carbonate, or sodium nitrate. The technician carries out two tests: first adding dilute hydrochloric acid, observing no fizzing; then adding a few drops of acidified barium chloride solution to a fresh sample dissolved in water, and observing a white precipitate form immediately.
(a)
State what each of the two test results shows about which anion is present or absent, and use both results together to identify the unlabelled white solid.
[3 marks]
(b)
Describe, including the reagents used and the observation expected, a further chemical test the technician could carry out to confirm that sodium ions, rather than another Group 1 metal ion, are present in the white solid.
[4 marks]
Total for question 7: 7 marks
8
A homeowner has two steel garden items: a steel gate that has been coated with a layer of oil-based paint, and a galvanised steel dustbin that has been coated with a thin layer of zinc. After several years outdoors, the paint on the gate has chipped in several places but the gate has not rusted at the chipped areas, while the dustbin has several deep scratches through the zinc layer but has also not rusted at the scratches.
(a)
Explain why the steel gate has not rusted at the chipped areas of paint, and describe the conditions that are normally needed for iron/steel to rust.
[6 marks]
(b)
Explain why the galvanised dustbin has not rusted at the scratches, even though the zinc coating has been broken through, and explain how this method of protection differs from the barrier method used on the gate.
[6 marks]
Total for question 8: 12 marks

End of questions