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Chemistry Past Paper Qs > paper 1 > Flashcards

paper 1 Flashcards

1
Q

Give the full electron configuration of an Al atom and a Cr3+ ion (2)

A

1) Al= 1s2 2s2 2p6 3s2 3p1
2) Cr3+ ion= 1s2 2s2 2p6 3s2 3p6 3d3

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2
Q

Deduce the formula of the compound that contains 2+ ions and 3- ions that both have same electron configuration as Argon (1)

A

Ca3P2

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3
Q

Deduce which of Na+ and Mg2+ is the smaller ion. Explain your answer (2)

A

1)Mg2+
2) Because Mg2+ has more protons with the same shielding

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4
Q

Write an equation to represent the process that occurs when the first ionisation energy of sodium is measured (1)

A

Na(g)—->Na+(g) + e-

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5
Q

Explain why the first ionisation energy of sulfur is different from that of phosphorus (2)

A

1)e− paired in 3p orbital in Sulfur
2) Paired e− repel so less energy needed to remove electron

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6
Q

Name the type of bond formed between N and Al in H3NAlCl3 and explain how this bond is formed (2)

A

1) co-ordinate bond
2) Shared pair of / both electrons come from the N(H3

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7
Q

In terms of structure and bonding, explain why the boiling point of bromine is different from magnessium and suggesy why magnessium is a liquid over much greater temperature range compared to bromine (5)

A

STRUCTURES
1) bromine is simple molecular
2) magnesium is metallic
STRENGTH
3) bromine has weak van der waals forces between the molecules
4) so more energy is needed to overcome the strong metallic bonds.
LQUID RANGE
5) Mg has much greater liquid range because forces of attraction in metal are stronger.

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8
Q

Explain how ions are accelerated,detected and have their abundance determined in a TOF mass spectrometer (3)

A

1)Ions accelerated by attraction to negatively charged plate
2)Ions detected by gaining electrons
3)Abundance determined by size of current flowing or amount of electrons gained in the detector

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9
Q

Student identified use of burette as largest source of uncertainty in the experiment. using same apparatus, suggest how procedure could be improved to reduce percentage uncertainty in using burette (2)

A

1) suggestion= use larger mass of solid
2) justification= so a larger titre will be needed

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10
Q

Student is required to make upto 250cm3 of aqueous solution that contains known mass of MHCO3. Student is provided with sample bottle containing the MHCO3. describe the method,including appratus and practical details,that student should use to prepare solution (6)

A

STAGE 1 - transfer known mass of solid (2 marks)
-weigh sample bottle containing solid on a 2 d.p. balance
-transfer to beaker and reweigh sample bottle
- record difference in mass
STAGE 2- dissolve in water (2 marks)
-add distilled water
-stir with glass rod until all solid dissolved
STAGE 3- transfer,washing and agitation ( 2 marks)
- transfer to volumetric flask with washings and make up to 250cm3
-shake/mix

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11
Q

Write the full electron configuration for Cl- and Fe2+ (2)

A

1)Cl− 1s2 2s2 2p6 3s2 3p6
2) Fe2+ 1s2 2s2 2p6 3s2 3p6 3d6

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12
Q

Write an equation, including state symbols, to represent the process that occurs
when the third ionisation energy of manganese is measured (1)

A

1) Mn2+ (g) → Mn3+ (g) + e−

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13
Q

State which of the elements magnesium and aluminium has the lower
first ionisation energy.
Explain your answer. (3)

A

1) Al
2)Outer electron in 3p orbital
3) Higher in energy/further from the nucleus
so easier to remove

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14
Q

Give the meaning of the term electronegativity (1)

A

Power of an atom to attract a pair of electrons in a covalent bond.

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15
Q

Explain how permanent dipole-dipole forces arise between hydrogen chloride
molecules (2)

A

1) Difference in electronegativity leads to bond polarity
2) and there is an attraction between ∂+ on one molecule and ∂- on
another

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16
Q

Name the shape of SiH4

A

Tetrahedral

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17
Q

Name the shape of BeCl2

A

Linear

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18
Q

Balance the equation ……CuFeS2 + ..…O2 + ..…SiO2 → ..…Cu2S + ..…Cu2O + ..…SO2 + ..…FeSiO3

A

4CuFeS2 + 9.5O2 + 4SiO2 → Cu2S + Cu2O + 7SO2 + 4FeSiO3

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19
Q

Balance the equation …….Cu2S + ……Cu2O → ……Cu + ……SO2

A

Cu2S + 2Cu2O → 6Cu + SO2

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20
Q

Suggest two reasons why the sulfur dioxide by-product of the process is removed
from the exhaust gases.

A

1) Prevents acid rain-which damages buidlings
2) Toxic

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21
Q

State two differences between the ‘plum pudding’ model and the model of atomic
structure used today (2)

A

1) nucleus now contains protons and neutrons
2)Electrons are now arranged in orbitals

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22
Q

deduce the full electron configuration of Nitrogen (1)

A

1s2 2s2 2p3

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23
Q

Explain how ions are detected and relative abundance is measured in a TOF mass
spectrometer (2)

A

1) ion hits the negative plate and gains an electron
2)relative abundance is proportional to the size of the current

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24
Q

Explain how the lone pairs of electrons on the oxygen atom influence the bond angle
in oxygen difluoride (OF2) (2)

A

1) Lone pairs repel more than bond pairs
2) bond angle will be lower

25
Q

Silicon tetrafluoride (SiF4) is a tetrahedral molecule.
Deduce the type of intermolecular forces in SiF4
Explain how this type of intermolecular force arises and why no other type of
intermolecular force exists in a sample of SiF4 (3)

A

1)Van der Waals forces
2) Uneven distribution of electrons in one molecule induces dipole in
another molecule
3)no hydrogens bonded to F (N or O), therefore no hydrogen bonding

26
Q

Sodium fluoride contains Na+ and F– which have the same electron configuration.
Explain why a fluoride ion is larger than a sodium ion. (2)

A

1)Fluoride ion has 2 fewer protons
2) Weaker attraction between nucleus and outer electrons

27
Q

Explain, in terms of structure and bonding, why the melting point of sodium fluoride is
high. (2)

A

1) Electrostatic forces of attraction between oppositely charged
ions/Na+
and F–
2) Lots of energy needed to overcome forces

28
Q

HF + H+ → H2F+
Name the type of bond formed when HF reacts with H+
Explain how this bond is formed. (2)

A

1)Coordinate bond / dative bond
2)Explanation: A lone pair of electrons is donated from F

29
Q

Draw the shape of the SbF6
– ion and the shape of the H2F+ ion. Include any lone pairs
that influence the shape.
Name the shape of each ion. (4)

A

1) shape of SbF-6
2) name: Octahedral
3) shape of H2F+
4) name: V-shaped

30
Q

Describe how the molecules are ionised using electrospray ionisation (3)

A

1) Sample is dissolved in a volatile solvent
2) Injected through needle at high voltage
3)Each molecule/particle gains a proton/H+

31
Q

Give an equation, including state symbols, for the process that occurs during the
ionisation of a germanium atom (1)

A

Ge(g) → Ge+
(g) + e–

32
Q

An atom has 2 more protons and 3 more neutrons than an atom of 52Cr.
Deduce the symbol, including the mass number and the atomic number, for this atom (1)

A

26𝐹𝑒 57

33
Q

The first ionisation energies of the elements in Period 2 change as the atomic number
increases.
Explain the pattern in the first ionisation energies of the elements from lithium to neon (6)

A

Stage 1: General Trend (Li → Ne)
-1st IE increases
-More protons/increased
nuclear charge
-Electrons in same energy level
-similar shielding
-Stronger attraction between
nucleus and outer e-
Stage 2: Deviation Be → B
-B lower than Be
-Outer electron in 2p which is higher in energy than 2s
Stage 3: Deviation N → O
-O lower than N
-2 electrons in 2p need to pair
pairing causes repulsion

34
Q

Before adding the solution from the burette in the rough titration, there was an
air bubble below the tap.
At the end of this titration the air bubble was not there.
Explain why this air bubble increases the final burette reading of the rough titration.(1)

A

Air bubble takes up volume that would be filled by solution/acid

35
Q

During the titration the student washed the inside of the conical flask with some
distilled water.
Suggest why this washing does not give an incorrect result (1)

A

Does not react with the alkali (water isn’t an reagent)

36
Q

Give a reagent, or combination of reagents, that can be added to the solutions in each
pair to distinguish between them in a single reaction.
State what is observed in each case.
1- NaCl(aq) and BaCl2(aq) (3m)
2-NaCl(aq) and Na2CO3(aq) (3m)

A

1-
Reagent: H2SO4 / Na2SO4
Observation with NaCl: no change
Observation with BaCl2: white ppt / white solid formed
2-
Reagent: H2SO4 / HCl / HNO3
Observation with NaCl: no (visible) change
Observation with Na2CO3: effervescence/bubbles/fizzing

37
Q

There is a general trend for an increase in ionisation energy across Period 3.
Give one example of an element that deviates from this trend.
Explain why this deviation occurs. (3)

A

Aluminium- Outer electron in 3p orbital 3p higher in energy than 3s
OR
Sulfur-Outer electrons in 3p orbital begin to pair and repel

38
Q

identify element x from the graph and explain your choice

A

1)Phosphorus
2)large jump in ionisation energy for the 6th ionisation energy
3)This is when the electron is being removed from the 2nd
energy level / from a lower energy level

39
Q

The student uses a funnel to fill the burette with sulfuric acid before starting the
titration. After filling, the student forgets to remove the funnel from the top of the
burette.
Suggest why this might affect the titre volume recorded. (1)

A

Additional drops of solution could have entered the burette from the funnel, making the value on the burette lower

40
Q

State one advantage of using a conical flask rather than a beaker for the titration (1)

A

Less chance of splashing/losing any solution using a conical flask
(when swirling)

41
Q

Define the term relative atomic mass(2)

A

1)The average mass of an atom of an element
2)Compared to 1/12th the mass of an atom of carbon-12

42
Q

State one observation when magnesium reacts with steam.
Give an equation, including state symbols, for this reaction. (2)

A

1)Bright light / white light / white powder/ash/solid
2)Mg(s) + H2O(g) → MgO(s) + H2(g)

43
Q

Describe the bonding in magnesium (2)

A

1)Attraction between (lattice of) Mg2+ ions
2)And delocalised electrons

44
Q

Explain, in terms of structure and bonding, why magnesium chloride has a
high melting point (3)

A

1)Giant ionic lattice / lots of Mg2+ and Cl– ions
2)Strong electrostatic forces of attraction
3)Between Mg2+ and Cl– ions

45
Q

Give one medical use for magnesium hydroxide

A

Indigestion relief /neutralise excess stomach acid

46
Q

Describe a further test, or tests, to show whether solution C contains chloride or
bromide ions (3)

A

1)Add dilute ammonia solution
2) If the precipitate dissolves chloride ions are present
3)If the precipitate does not dissolve then bromide ions are present

47
Q

Chlorine has a low boiling point because the forces between the molecules are weak.
Explain how these forces arise between molecules of chlorine (3)

A

1)Random movement of electrons in one molecule creates a dipole in one molecule
2)Induces a dipole in a neighbouring molecule.
3)temporary attraction between δ+
and δ–

48
Q

Give an equation for the reaction of chlorine with water

A

Cl2 + H2O ⇌ HCl + HClO / 2 Cl2 + 2 H2O → 4 HCl + O2

49
Q

Give a reason why chlorine is added to drinking water

A

Kills bacteria / kills microorganisms / kills microbes / kills pathogens

50
Q

The student rinses the burette with deionised water before filling with
sodium hydroxide solution.
State and explain the effect, if any, that this rinsing will have on the value of the titre (2)

A

1)Titre value would increase
2) Because the sodium hydroxide solution would be more dilute

51
Q

Explain why silicon dioxide has a higher melting point than sulfur trioxide (4)

A

1)Covalent bonds in SiO2
2)Van der Waals between molecules in SO3
3)Covalent bonds are stronger than van der Waals forces
4)Covalent bonds take more energy to be overcome/broken OR
Van der Waals take less energy to be overcome/broken

52
Q

State the type of crystal structure shown in
1)silicon dioxide
2)sulfur trioxide

A

1)macromolecular/giant covalent
2)simple molecule

53
Q

Explain why the second ionisation energy of calcium is lower than the second
ionisation energy of potassium (2)

A

1)In Ca+,outer electrons are further from nucleus
2)More shielding in Ca+

54
Q

Identify the s-block metal that has the highest first ionisation energy

A

Be /Beryllium

55
Q

Why isotopes of strontium have identical chemical properties

A

Same electronic configuration

56
Q

State the meaning of the term strong acid.

A

completely ionises to form H+
ions

57
Q

Use your knowledge of structure and bonding to explain why sodium bromide has a
melting point that is higher than that of sodium, and higher than that of sodium iodide (6)

A

Stage 1- Na
1) Na has metallic bonding
there is attraction between the positive ion and the delocalised electrons in Na
2) Na has a giant/lattice structure
Stage 2 – NaBr or NaI
3) Ionic bonding in NaBr and/or NaI
There is attraction between the + and –
ions in NaBr and/or NaI
4) NaBr and/or NaI have a giant/lattice structure
Stage 3 - comparison of bonding
5) The ionic bonds are stronger than the
metallic bonds
6) there is stronger attraction between the
+ and – ions in NaBr than in NaI since the Br –
ion is smaller than the I– ion

58
Q

Identify the element in Period 4 with the largest atomic radius.
Explain your answer. (3)

A

1)Potassium
2)Smallest number of protons/smallest nuclear charge
3)Similar shielding as other period 4 elements

59
Q

Copper(I) iodide is a white solid.
Explain why copper(I) iodide is white (2)

A

1)Full 3d subshell
2)cannot absorb visible/white light

Chemistry Past Paper Qs (1 decks)

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