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Chemistry Paper 1 Flashcards

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1
Q

What is the molecular and empirical formula for ethene

A
  • Empirical: CH2
  • Molecular: C2H4
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2
Q

What formula of an ion makes a hydrogen chloride solution acidic

A
  • H+
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3
Q

Why may a water with impurities be potable

A
  • Because the impurities are harmless (made up of minerals and ions)
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4
Q

It was concluded that the best way to purify 1000cm3 of the waste water is to add 100mg of salt B, Use the information about salt A and salt B to evaluate this conclusion.

A
  • 100 mg of A removes 40% impurities
  • 100 mg of B removes 44% impurities
  • so salt B is better than salt A as more impurities are removed for same mass of salt
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5
Q

Aluminium ions react with phosphate ions to form aluminium phosphate.

Complete the ionic equation for the formation of aluminium phosphate in this reaction

A
  • Al(3+) + PO^4(3-) → AlPO^4
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6
Q

A sample of molten potassium bromide is electrolysed.
What are the two products formed?

A
  • potassium and bromine
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7
Q

Zinc chloride mixed with water can be electrolysed.
Zinc carbonate mixed with water cannot be electrolysed.

Explain this difference.

A
  • zinc chloride is soluble and zinc carbonate is insoluble
  • so ions free to move only in zinc chloride solution
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8
Q

Explain how hydrogen is formed at the cathode

A
  • hydrogen ions attracted to cathode
  • two hydrogen ions gain two electrons and are reduced
  • 2H + 2e- —> H^2
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9
Q

During the electrolysis, the anode gets smaller, the cathode gets larger and
the solution remains the same shade of blue in copper sulfate solutions

Why?

A
  • Anode: smaller because copper atoms form ions and go into solution (oxidation of Cu atoms)
  • Cathode: larger because copper atoms are formed from ions in the solution and reduction of Cu(2+)
  • Solution: the same number of ions enter and leave solution
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10
Q

During the reaction, the pH of the mixture changed from 2 to 6.

By what factor has the concentration of the hydrogen ions in the mixture changed?

A
  • 1/10,000
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11
Q

CuSO4.5H2O → CuSO4 + 5H2O

Calculate the mass of hydrated copper sulfate that was heated.

A
  • Mass / MR = Mole
  • moles of H2O = 4.5 / 18.0 = 0.25
  • moles CuSO4.5H2O = 0.25/5 = 0.05
  • mass CuSO4.5H2O = 0.05 x 249.5 = 12.475 g
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12
Q

The order of reactivity of copper, magnesium and zinc can be determined by the displacement reactions between these metals and solutions of their salts.

Describe the experiments that can be done to determine the order of reactivity of these metals by displacement reactions

A
  • place separate pieces of each metal into solutions of each of salt
  • observe changes in colour of solution
  • the more reactive metal shows the greater number of reactions
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13
Q

Explain why aluminium cannot be extracted from its ore by heating with carbon but can be extracted by electrolysis.

A
  • aluminium is more reactive than carbon
    so electrolysis required
  • carbon cannot remove the oxygen as aluminium is more reactive
  • electrolysis can be used to reduce aluminium ions
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14
Q

Suggest how pure titanium chloride could be separated from the impurities

A
  • simple distillation
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15
Q

there is a mixture of the solids magnesium, titanium and magnesium chloride. Titanium does not react with dilute hydrochloric acid.
Suggest a simple method to separate titanium from the mixture.

A
  • filter off the titanium
  • Then wash the titanium
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16
Q

Deduce, using the information in Figure 4, the structure and bonding of substances A, B and C, explaining their properties in terms of their structure and bonding.

A
  • Substance A: giant ionic structure, strong electrostatic attractions between ions from high melting point needs a lot of energy to overcome it, poor conductor when solid as ions can’t move freely
  • Substance B: metallic structure, strong attraction between metal ions and delocalised electrons from high melting point and needs a lot of energy to overcome it, free to move throughout metallic lattice so good conductor when solid
  • Substance C: covalent simple molecular, weak attractions between molecules from low melting point so doesn’t need that much energy to overcome it, in solid and when molten, no delocalised electrons so it’s a poor conductor
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17
Q

Element X has an atomic number of 18.
State the electronic configuration of an atom of element X.

A
  • 2.8.8
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18
Q

In an experiment, 3.5 g of element A reacted with 4.0 g of element G to form
a compound.
Calculate the empirical formula of this compound.

A
  • Find moles from each (mass/mr)
  • Empirical formula = 2:1
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19
Q

When molten zinc chloride is electrolysed, zinc ions, Zn2+, form zinc atoms.
Write the half equation for this reaction.

A
  • Zn (2+) + 2e- → Zn
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20
Q

Nickel is extracted from nickel compounds.
State an advantage of extracting nickel by phytoextraction rather than from
its ore.

A
  • decontaminates ground
  • less carbon dioxide
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21
Q

An advantage of producing a metal by electrolysis is that

A
  • the metal produced by electrolysis is very pure
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22
Q

Describe what you would see when an excess of zinc is added to copper sulfate solution and the mixture left until the reaction is complete.

A
  • orange solid formed
  • some grey solid will remain
  • blue solution becomes colourless
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23
Q

Zn(s) + CuSO4(aq) o ZnSO4(aq) + Cu(s)

This reaction is described as a redox reaction.
Explain, in terms of electrons, which particles have been oxidised and which
particles have been reduced in this reaction.

A
  • zinc oxidised
  • because zinc lose electrons
  • copper ions reduced
  • because copper ions gained electrons
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24
Q

State how you could change the method so that the amounts of dilute
hydrochloric acid and of the base can be measured more accurately.

A
  • Dilute HCL: use measuring cylinder
  • Base: Weigh out amount using a balance
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25
Q

During the experiment the pH changes from 2 to 10.

If phenolphthalein indicator is added at the beginning of the experiment, a
colour change occurs as the base is added.

A
  • Colourless to pink
26
Q

Explain, in terms of the particles present, why the pH increases during the experiment.

A
  • Hydrogen ions neutralise
  • There are fewer H+ ions
27
Q

Identify the solids A, B, C and D, explaining how the information in Figure 3 supports the identification of each solid.

A
  • Solid A: Copper oxide, copper oxide reacts with sulfuric acid to make copper sulfate but no gas
  • Solid B: Magnesium, magnesium reacts with sulfuric acid to give hydrogen
  • Solid C: Sodium Hydroxide, sodium hydroxide reacts with sulfuric acid to form a colourless solution
    -Solid D: Copper Carbonate, copper carbonate reacts with sulfuric acid to form carbon dioxide and copper sulfate
28
Q

Describe the test to show the gas is hydrogen.

A
  • apply lighted splint
  • Squeaky pop
29
Q

Aluminium cannot be extracted by heating its oxide with carbon.
Aluminium has to be extracted from its oxide by electrolysis.
Explain why.

A
  • aluminium is high in reactivity
  • So it can’t be reduced by carbon
30
Q

Predict the method that will have to be used to extract calcium from its ore.

A
  • electrolysis
31
Q

Describe how growing plants can result in the phytoextraction of copper.

A
  • plants absorb copper ions from the soil
  • plants harvested and burned to leave
    copper
32
Q

Explain how the apparatus could be improved to increase the amount of
pure water collected from the same volume of sea water.

A
  • Use Liebig condenser
  • ensure all the water vapour condenses
33
Q

Why did anode decrease in mass and cathode increase

A
  • copper ions move into solution at anode and copper ions move out of solution at cathode
  • at anode copper atoms become copper ions and lose two electrons
  • at cathode copper ions become copper atoms and gain two electrons
34
Q

Write the half equation for the formation of hydrogen gas, H2, from hydrogen ions, H+

A
  • 2H(+) + 2e(-) → H^2
35
Q

the arrangement of carbon atoms in diamond, graphene and a
fullerene (C60) is shown. Explain, in terms of their structures and bonding, their relative melting points,
strengths and abilities to conduct electricity.

A
  • in all structures the carbon atoms bonded by single covalent
    bonds
  • shared pair of electrons and strong bonds
  • Diamond: Giant covalent, each carbon atom joined to four others, high melting point due to strong bonds that require lots of energy to overcome, no free electrons and doesn’t conduct electricity
  • Graphene: Giant covalent, high melting point due to strong bonds that require lots of energy to overcome, each carbon atom joined to three others, one free delocalised electron so can conduct electricity
  • Fullerene: Molecular structure, each carbon atom joined to three others, weak forces between molecules and results in low melting point, only conducts electricity across the surface of molecule as there is little movement of electrons between molecules.
36
Q

Give a reason why the start line is drawn in pencil rather than in ink.

A
  • Pencil is insoluble in the solvent
37
Q

Give a change that could be made to the experiment to obtain an Rf
value for the insoluble colouring.

A
  • use a different solvent.
38
Q

When zinc reacts with dilute hydrochloric acid, a gas is given off and zinc chloride
is formed. which gas

A
  • hydrogen
39
Q

State two factors, concerning the hydrochloric acid, which should also be
controlled to produce valid results.

A
  • volume
  • temperature
40
Q

Which material is most suitable to make the electrodes for the electrolysis of a
dilute acid?

A
  • graphite
41
Q

When a solution of sodium sulfate, Na2
SO4 , is electrolysed, the products formed at

the electrodes are hydrogen and oxygen.
Explain the formation of the products at the electrodes.

A
  • hydrogen (H+) and sodium (Na+) ions attracted to cathode
  • because the ions are attracted to the oppositely charged electrode
  • 2 hydrogen ions gain 2 electrons
  • 4 hydroxide ions lose 4 electrons
42
Q

State two ways in which this model fails to accurately represent a crystal of
sodium chloride.

A
  • Particles are same size when
    they should be different sizes
  • Model is in 2D but crystal is
    3D
43
Q

Magnesium oxide has a melting point of 2852°C.
Explain why magnesium oxide has such a high melting point.

A
  • very strong bonds
  • between 2+ cations and 2– anions
  • so requires lot of energy to separate magnesium and oxide ions to melt the solid
44
Q

Carbon dioxide can be formed by the reaction of calcium carbonate, CaCO3,
with dilute hydrochloric acid.
Write the balanced equation for this reaction.

A
  • CaCO3 + 2HCl → CaCl2 + H2O + CO2
45
Q

Explain the difference between a strong acid and a weak acid.

A
  • a strong acid is completely ionised in solution
  • but a weak acid is only partly ionised
46
Q

Give a reason why adding hydroxide ions to an acid solution leads to an
increase in pH.

A
  • hydroxide ions react with hydrogen ions and reduce the hydrogen
    ion concentration therefore increase pH
47
Q

The salt zinc nitrate can be made by reacting zinc oxide, ZnO, with dilute
nitric acid, HNO3
Write the balanced equation for this reaction.

A
  • ZnO + 2HNO3 → Zn(NO3)2 + 2H2O
48
Q

50cm3 of potassium hydroxide solution of concentration 40g dm–3 is needed for
an experiment. Calculate the mass of potassium hydroxide that must be dissolved in water to make 50cm3
of solution of this concentration.

A
  • 50 x 40/1000 = 2g
49
Q

Salts of metals can be made by reacting one of the metal’s compounds with the
appropriate acid.
Plan an experiment to prepare pure, dry crystals of magnesium sulfate, MgSO4 , by reacting a suitable magnesium compound with a suitable acid.

A
  • suitable acid: sulfuric acid
  • suitable substance : magnesium oxide
  • add solid a little at a time until no more bubbles
  • filter off the excess solid, pour remaining solution into an evaporating
    basin
  • leave the water to evaporate
  • until pure salt crystals form and then leave salt crystals out to dry
50
Q

Name a piece of equipment which could be used to measure out 50.0cm3
of dilute hydrochloric acid more accurately than the measuring cylinder.

A
  • a pipette
51
Q

The atomic number of magnesium is 12.
What is the electronic configuration of the Mg2+ ion?

A
  • 2.8
52
Q

The atomic number of magnesium is 12.
What is the electronic configuration of the Mg2+ ion?

A
  • 2.8
53
Q

Explain, in terms of ions, the changes in mass of the two electrodes

A
  • at anode copper atoms lose electrons and cause mass loss
  • Copper ions move from solution to the cathode
  • at cathode copper ions gain electrons and causes mass gain
54
Q

Explain a change that could be made to the electrolysis experiment to cause
the mass of the cathode to increase by 2.34g in 10 minutes.

A
  • 2.34/0.78 = 3
  • increase copper mass by 3x
  • 3x more current running through the solution
55
Q

Explain why this displacement reaction can be described as a redox reaction.

A
  • redox involves both reduction and oxidation
  • magnesium atoms lose electrons and are oxidised
  • titanium ions gain electrons and are reduced
56
Q

Explain why the reaction between metal Y and excess dilute sulfuric acid
stopped even though there was solid metal Y left.

A
  • metal sulfate is insoluble and so prevents reaction of metal and acid
57
Q

The formula of aluminium sulfate is Al
2 (SO4)3
Calculate the total number of atoms that combine to form 5.13g of aluminium sulfate.

A
  • formula mass Al2(SO4)3 = 2x27 + 3x(32 + 16x4) = 342
  • moles = 5.13/342 = 0.015
  • number of atoms = 17
  • number of atoms in 0.015 moles = 17 x 0.015 x avragado’s constant
58
Q

In one experiment, it was found that 4.48g of iron reacted with excess lead nitrate solution to form 24.84g of lead.
Carry out a calculation, using the information above, to show which equation represents the reaction taking place.

A
  • Find mole of iron
  • Find mole of lead
  • If ratio between moles doesn’t equal 1:1 then it is the other equation
59
Q

Explain how, in this reaction, magnesium and oxygen atoms form a solid that has
a high melting point.

A
  • each magnesium atom loses two electrons
  • forms cation Mg(2+)
  • Mg —> Mg(2+) + 2e-
  • electrons transferred from magnesium atoms to oxygen atoms
  • each oxygen atom gains two electrons
  • forms anion O(2-)
  • O + 2e- —-> O(2-)
  • ionic bonds form between oppositely charged ions
  • strong electrostatic forces between oppositely charged ions
  • Requires large amount of energy to overcome, thus high melting point
60
Q

Some of the solution remaining after the electrolysis was tested with litmus paper.
The paper turned blue.
Explain why the litmus paper turned blue.

A
  • Solution is alkaline
  • Excess hydroxide ions are present and sodium hydroxide solution is formed

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