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Chem Exam Qs > E/P Qs > Flashcards

E/P Qs Flashcards

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1
Q

What is an orbital

2

A

Region of space around nucleus that can hold up to 2 electrons with opposite spins.

Strictly this

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2
Q

Which block of periodic table would you find nickel or copper

A

D block

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3
Q

Structure and bond in SiO2

A

Giant covalent structure and single covalent bonds

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4
Q

What is the term given to the “ . x H2O” in a crystallised salt

A

Water of crystallisation

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5
Q

What is the relative mass of an electron

A

Negligible or 1/2000

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6
Q

What is meant by the term mole

A

Amount of substance that has same number of particles as there are atoms in 12g of carbon 12/
Avogadro’s number

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7
Q

Reaction of magnesium with water balanced equation

A

Ca + 2H2O arrow Ca(OH)2 + H2

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8
Q

Molecular formula meaning

A

Number and type of atoms making up a molecule or the number of atoms of each element

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9
Q

Why does magnesium have higher mp than chlorine

Structure and bonding explanation
6 marks

A

Mg has giant structure, metallic bonding, electrostatic attraction between cations and electrons. Cl has simple molecular with van der waals forces (london forces) between molecules which require less energy to overcome than metallic bonds.

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10
Q

Suggest why H2S has lower bp than H2O

A

No hydrogen bonding

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11
Q

What is electronegativity

A

Attraction of an atom for electrons in a covalent bond

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12
Q

Explain why the bp increases from sodium(group 1, 11 electron) to aluminium( grp 3, 13 electron)

A

Number of delocalised electrons increases, cation charge increases and attraction increases/metallic bonding gets stronger

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13
Q

Describe the structure of NaCl

A

Giant ionic lattice with alternating Na+ and Cl-

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14
Q

Shape and angle of SO2
S has 16 electrons
O has 8

A

Non linear 117.5

Or in range from 110-130

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15
Q

Predict the bond angle in SbH3 Sb is grp 5 element along with N

A

107 cos 3bp 1lp

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16
Q

At room temp X, is a liquid that doesn’t conduct electricity

Bonding and structure ofX?

A

Simple molecular (covalent bonding)

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17
Q

Predict with reason the bond angle of ammonia

4 marks

A

107
Electron pairs repel other electron pairs
Lone pair has more repulsion
Electron pairs get as far apart as possible

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18
Q

Suggest why PH3 has a lower bp than NH3

A

PH3 has weaker intermolecular forces

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19
Q

What is meant by term isotopes

A

Atom(s) of an element with different number of neutrons (and with different masses)

Strictly this

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20
Q

Why do isotopes have same chemical properties

A

Same number of electrons in outer shell
Or same electron config
Or same electron structure

Strictly this!

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21
Q

Define relative atomic mass

A

The weighted ‘mean mass of an atom compared with 1/12 mass of a carbon 12’ atom

Strictly this

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22
Q

SbCl3 is polar
Why
2 marks

A

Difference in electronegativity or have a dipole

Molecule is not symmetrical so dipoles don’t cancel out

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23
Q

Why do all grp 7 elements react similarly to each other

A

Have same number of electrons in outer shell

Strictly this

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24
Q

Why does sodium oxide not conduct electricity when solid state

A

Ions are fixed in position in a lattice

Strictly this

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25
Q

Why does first ionisation energy decrease from mg to al?
Same period
(2)

A

Mg electron removed from 3s and Al electron removed from 3p sub shell
3p has higher energy than 3s

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26
Q

How can GC-MS identify compound

A

GC separates the components and allows RF to be calculated and compared to data-books/ values and identify compound. Mass spectra allows fragment ions analysed

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27
Q

Why is TMS used in NMR

A

It is a standard which sample is compared to/reference

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28
Q

Why is deuterated solvents used in proton NMR

A

It has no H which would show up in H NMR as a peak

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29
Q

How use GC to predict compounds and relative proportion

A

From retention times and from their peak areas

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30
Q

Why would there be uncertainty about using GC alone to predict number of esters in mixture

A

Some have very similar retention times

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31
Q

Use of nmr in medicine

Region of electromagnetic spectrum used in proton NMR

A

MRI scans

Radio waves

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32
Q

Describe test to confirm carbonyl group and product identify carbonyl compound

A

2,4DNP and form orange precipitate
Crystal melting point and compare to database and known values

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33
Q

What do curly arrows represent

A

Movement of an electron pair

34
Q

Heterolytic fission?

A

Breaking of covalent bond
And when one species takes both electrons

35
Q

Number of stereoisomers the Ni (en)2 Cl2 can form

A

3 as 2 cis trans and one of cis is an optical isomer

Be careful not to count optical and cis isomer twice

36
Q

Tru/Fals? Abt transition element
Element has atoms with partially filled d sub shell

Multiple oxidation state in compounds

Form coloured ions

A

F as it is not atom, it is its ions
T
T

37
Q

Explain which block is sodium in

A

S block and highest energy electron in s sub shell

38
Q

Why is lattice enthalpy of K2O less exothermic than Na2O
K number is 19, Na atomic number is 11

(2)

A

Na has smaller atomic radius so nuclear attraction increases

39
Q

Oxidation equation of alcohol to carboxylic acid

A

Alcohol + 2[O] —> carboxylic acid +H2O

40
Q

How to recrystallise to obtain pure sample from impure
(2)

A

Dissolve in MINIMUM quantity of HOT solvent

Let it cool, filter and dry

41
Q

Test for phenol

A

Add bromine and white precipitate or
pH paper turns red but no reaction with carbonate

42
Q

SF6 bond angle and shape

A

Octahedral
90

43
Q

Which element react reacts with water to form an acidic solution

A

Cl
As disproportionation as HCl and HClO formed

44
Q

Why can in some cases kc calculated using number of moles rather than cOnc

A

Same volume cancels out or same number of moles in each side of equation

45
Q

What technique to determine equilibrium amount of a weak acid

A

Titration

46
Q

2 disadv and adv of fuel cells than fossil fuels

(4)

A

Adv: only H2O formed so non polluting
Greater efficiency

Disadv:
H2 difficult to store
H2 difficult to manufacture/ limited life cycle of H2 absorber

47
Q

Standard electrode potential?

(3)

A

Potential difference of electrochemical cell comprising of a half cell combined with a standard hydrogen electrode
100kPa, 1M, 298K

48
Q

Diagram on how to measure electrode potential of Cu half cell

A

Cu half cell with Cu ions and copper rod
Attach to hydrogen half cell which is platinum electrode, H2 gas input, H+ solution 1M
Salt bridge and voltmeter

49
Q

Why is a polymer with C=O bond more likely to be degradeable
(2)

A

C=O absorb radiation and breaks and ester link hydrolysed.

50
Q

Explain process of addition polymerisation

A

Monomers with C=C
High pressure and temp
Pi bond breaks and many molecules join to form a long chain

51
Q

Explain how en act as bidentate ligand
(2)

A

Donates 2 lone pairs to metal ion
Lone pair on N

52
Q

Aq Cu2+ and NH3
Complex ion and colour

A

Blue
[Cu (NH3)4(H2O)2]2+

53
Q

What is an a (alpha) amino acid general formula

A

RCH(NH2)COOH

The C is a chiral centre

54
Q

Nitrobenzene to phenylamine
Equation and conditions

A

Nitrobenzene + 6[H] —> phenylamine +2H2O

Sn and conc HCl and excess NaOH
Heat reflux

55
Q

Entropy definition

A

Measure of dispersal of energy
Or degree of disorder

56
Q

Why is first ionisation energy of He and Be higher than Li
He - 2
Li-3
Be-4

(4)

A

Electrons are in lower energy in He so greater nuclear attraction on outer shell electron

Nuclear charge increase for Be so decrease in atomic radius

57
Q

Explain why buffer solution formed

A

Acid is partially neutralised and A- ions produced

58
Q

Why are operational conditions different in industry

A

High pressure expensive and dangerous but can increase yield
Increase temp for faster rate of reaction but lower yield
Catalyst reduce fuel expense and increase rate

59
Q

2 observation that shows ca more reactive than mg when add water

A

Ca fizzes faster
Ca dissolves quicker

60
Q

Why does increasing temp increase rate of reaction
(2)

A

Faster rate and more frequent collisions
More particles have energy above Ea

Strictly this

61
Q

Average bond enthalpy

A

Enthalpy change/ energy required to break 1 mole of a specific covalent bond in gas phase

62
Q

Describe and explain factors affecting value of Lattice enthalpy
(3)

A

Decrease in ionic size and increase in charge so more negative LE and more attraction
Attraction between ions

63
Q

Explain why reaction happen spontaneously even if negative entropy change and negative enthalpy change
(1)

A

Negative value of H more significant than negative value of tS

64
Q

Explain difference in LE between NaF, NaCl and MgF2

(3)

A

Cl ion larger than F so smaller charge density
mg2+ is smaller than Na+ and has greater charge

F- greater attraction for cation
Mg2+ greater attraction for anion

65
Q

Explain in terms of kc why equilibrium yield of ammonia (product) increase as pressure increase
(3)

A

Kc is same
Increased pressure increases conc terms on bottom of kc expression more than top
Top of kc expression increase and bottom decrease until kc reached

66
Q

A solid organic compound purified by recrystallisation
True/false

Organic compound more soluble in hot solvent

Hot solution cooled before pure organic compound collected

MP of purified compound is lower than impure

A

True
True
False as mp of impure is lower and wider range

67
Q

Iodine-sodium thiosulfate titration what indicator and colour change in end point

A

Starch
Black to colourless

68
Q

Test for ammonium ion

A

Add NaOH and then heat
Gas produced and put near damp red litmus paper blue

69
Q

How to store hydrogen in hydrogen fuel cell

A

Liquified under pressure

70
Q

Two reasons why uncertain whether reaction predicted from E values may not take place

(2)

A

Slow rate
Conditions not standard

71
Q

Standard solution preparation

A

Weigh out mass of solid
Dissolve in small amount of distill water in beaker less than 250cm3
Transfer to 250cm3 volumetric flask and rinse beaker and add washings to volumetric flask
Make up to the mark line and meniscus base is on line
Mix by inverting the volumetric flask after putting stopper

72
Q

Equation for lattice enthalpy of magnesium bromide

A

Mg2+ (g) + 2Br1(g) arrow MgBr2 (s)

73
Q

Which type of reaction has highest atom economy
Substitution
Hydrolysis
Elimination
Addition

A

Addition

74
Q

Which compound in water is most acidic
Carboxylic acid or acyl chloride

A

Acyl chloride as cl can disproportionation with water and form HClO and HCl
It is more reactive and acidic

75
Q

Explain why reactive increases down grp 2 metals

(3)

A

Atomic radius increase
More shielding
Nuclear attraction decreases
Ionisation energy decreases

76
Q

Enthalpy change of hydration
(2)

A

1 mole of gaseous ions dissolve in water and form hydrated ions

77
Q

Predict and explain enthalpy of hydration of F- and Cl-
(2)

A

F- is more negative as F ion smaller size
F ion has greater attraction to water

78
Q

Average bond enthalpy
(2)

A

Breaking of 1 mole of bond in gaseous molecule

79
Q

Explain why difficult to predict whether enthalpy change of solution become more or less exothermic down group for magnesium halide
(4)

A

Halide ion larger down grp
LE less exothermic down grp
Hydration enthalpy is less exothermic down grp
Difficult to predict whether LE or hydration enthalpy has bigger effect

80
Q

Bidentate ligand?
(2)

A

Donates two lone pairs of electron and form 2 coordinate bonds to metal ion

81
Q

1 important feature of fuel cell thats different from conventional storage cell
(1)

A

Fuel react with oxygen to give electrical energy

Chem Exam Qs (1 decks)

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