E/P Qs Flashcards
What is an orbital
2
Region of space around nucleus that can hold up to 2 electrons with opposite spins.
Strictly this
Which block of periodic table would you find nickel or copper
D block
Structure and bond in SiO2
Giant covalent structure and single covalent bonds
What is the term given to the “ . x H2O” in a crystallised salt
Water of crystallisation
What is the relative mass of an electron
Negligible or 1/2000
What is meant by the term mole
Amount of substance that has same number of particles as there are atoms in 12g of carbon 12/
Avogadro’s number
Reaction of magnesium with water balanced equation
Ca + 2H2O arrow Ca(OH)2 + H2
Molecular formula meaning
Number and type of atoms making up a molecule or the number of atoms of each element
Why does magnesium have higher mp than chlorine
Structure and bonding explanation
6 marks
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.
Suggest why H2S has lower bp than H2O
No hydrogen bonding
What is electronegativity
Attraction of an atom for electrons in a covalent bond
Explain why the bp increases from sodium(group 1, 11 electron) to aluminium( grp 3, 13 electron)
Number of delocalised electrons increases, cation charge increases and attraction increases/metallic bonding gets stronger
Describe the structure of NaCl
Giant ionic lattice with alternating Na+ and Cl-
Shape and angle of SO2
S has 16 electrons
O has 8
Non linear 117.5
Or in range from 110-130
Predict the bond angle in SbH3 Sb is grp 5 element along with N
107 cos 3bp 1lp
At room temp X, is a liquid that doesn’t conduct electricity
Bonding and structure ofX?
Simple molecular (covalent bonding)
Predict with reason the bond angle of ammonia
4 marks
107
Electron pairs repel other electron pairs
Lone pair has more repulsion
Electron pairs get as far apart as possible
Suggest why PH3 has a lower bp than NH3
PH3 has weaker intermolecular forces
What is meant by term isotopes
Atom(s) of an element with different number of neutrons (and with different masses)
Strictly this
Why do isotopes have same chemical properties
Same number of electrons in outer shell
Or same electron config
Or same electron structure
Strictly this!
Define relative atomic mass
The weighted ‘mean mass of an atom compared with 1/12 mass of a carbon 12’ atom
Strictly this
SbCl3 is polar
Why
2 marks
Difference in electronegativity or have a dipole
Molecule is not symmetrical so dipoles don’t cancel out
Why do all grp 7 elements react similarly to each other
Have same number of electrons in outer shell
Strictly this
Why does sodium oxide not conduct electricity when solid state
Ions are fixed in position in a lattice
Strictly this
Why does first ionisation energy decrease from mg to al?
Same period
(2)
Mg electron removed from 3s and Al electron removed from 3p sub shell
3p has higher energy than 3s
How can GC-MS identify compound
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
Why is TMS used in NMR
It is a standard which sample is compared to/reference
Why is deuterated solvents used in proton NMR
It has no H which would show up in H NMR as a peak
How use GC to predict compounds and relative proportion
From retention times and from their peak areas
Why would there be uncertainty about using GC alone to predict number of esters in mixture
Some have very similar retention times
Use of nmr in medicine
Region of electromagnetic spectrum used in proton NMR
MRI scans
Radio waves
Describe test to confirm carbonyl group and product identify carbonyl compound
2,4DNP and form orange precipitate
Crystal melting point and compare to database and known values
What do curly arrows represent
Movement of an electron pair
Heterolytic fission?
Breaking of covalent bond
And when one species takes both electrons
Number of stereoisomers the Ni (en)2 Cl2 can form
3 as 2 cis trans and one of cis is an optical isomer
Be careful not to count optical and cis isomer twice
Tru/Fals? Abt transition element
Element has atoms with partially filled d sub shell
Multiple oxidation state in compounds
Form coloured ions
F as it is not atom, it is its ions
T
T
Explain which block is sodium in
S block and highest energy electron in s sub shell
Why is lattice enthalpy of K2O less exothermic than Na2O
K number is 19, Na atomic number is 11
(2)
Na has smaller atomic radius so nuclear attraction increases
Oxidation equation of alcohol to carboxylic acid
Alcohol + 2[O] —> carboxylic acid +H2O
How to recrystallise to obtain pure sample from impure
(2)
Dissolve in MINIMUM quantity of HOT solvent
Let it cool, filter and dry
Test for phenol
Add bromine and white precipitate or
pH paper turns red but no reaction with carbonate
SF6 bond angle and shape
Octahedral
90
Which element react reacts with water to form an acidic solution
Cl
As disproportionation as HCl and HClO formed
Why can in some cases kc calculated using number of moles rather than cOnc
Same volume cancels out or same number of moles in each side of equation
What technique to determine equilibrium amount of a weak acid
Titration
2 disadv and adv of fuel cells than fossil fuels
(4)
Adv: only H2O formed so non polluting
Greater efficiency
Disadv:
H2 difficult to store
H2 difficult to manufacture/ limited life cycle of H2 absorber
Standard electrode potential?
(3)
Potential difference of electrochemical cell comprising of a half cell combined with a standard hydrogen electrode
100kPa, 1M, 298K
Diagram on how to measure electrode potential of Cu half cell
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
Why is a polymer with C=O bond more likely to be degradeable
(2)
C=O absorb radiation and breaks and ester link hydrolysed.
Explain process of addition polymerisation
Monomers with C=C
High pressure and temp
Pi bond breaks and many molecules join to form a long chain
Explain how en act as bidentate ligand
(2)
Donates 2 lone pairs to metal ion
Lone pair on N
Aq Cu2+ and NH3
Complex ion and colour
Blue
[Cu (NH3)4(H2O)2]2+
What is an a (alpha) amino acid general formula
RCH(NH2)COOH
The C is a chiral centre
Nitrobenzene to phenylamine
Equation and conditions
Nitrobenzene + 6[H] —> phenylamine +2H2O
Sn and conc HCl and excess NaOH
Heat reflux
Entropy definition
Measure of dispersal of energy
Or degree of disorder
Why is first ionisation energy of He and Be higher than Li
He - 2
Li-3
Be-4
(4)
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
Explain why buffer solution formed
Acid is partially neutralised and A- ions produced
Why are operational conditions different in industry
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
2 observation that shows ca more reactive than mg when add water
Ca fizzes faster
Ca dissolves quicker
Why does increasing temp increase rate of reaction
(2)
Faster rate and more frequent collisions
More particles have energy above Ea
Strictly this
Average bond enthalpy
Enthalpy change/ energy required to break 1 mole of a specific covalent bond in gas phase
Describe and explain factors affecting value of Lattice enthalpy
(3)
Decrease in ionic size and increase in charge so more negative LE and more attraction
Attraction between ions
Explain why reaction happen spontaneously even if negative entropy change and negative enthalpy change
(1)
Negative value of H more significant than negative value of tS
Explain difference in LE between NaF, NaCl and MgF2
(3)
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
Explain in terms of kc why equilibrium yield of ammonia (product) increase as pressure increase
(3)
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
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
True
True
False as mp of impure is lower and wider range
Iodine-sodium thiosulfate titration what indicator and colour change in end point
Starch
Black to colourless
Test for ammonium ion
Add NaOH and then heat
Gas produced and put near damp red litmus paper blue
How to store hydrogen in hydrogen fuel cell
Liquified under pressure
Two reasons why uncertain whether reaction predicted from E values may not take place
(2)
Slow rate
Conditions not standard
Standard solution preparation
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
Equation for lattice enthalpy of magnesium bromide
Mg2+ (g) + 2Br1(g) arrow MgBr2 (s)
Which type of reaction has highest atom economy
Substitution
Hydrolysis
Elimination
Addition
Addition
Which compound in water is most acidic
Carboxylic acid or acyl chloride
Acyl chloride as cl can disproportionation with water and form HClO and HCl
It is more reactive and acidic
Explain why reactive increases down grp 2 metals
(3)
Atomic radius increase
More shielding
Nuclear attraction decreases
Ionisation energy decreases
Enthalpy change of hydration
(2)
1 mole of gaseous ions dissolve in water and form hydrated ions
Predict and explain enthalpy of hydration of F- and Cl-
(2)
F- is more negative as F ion smaller size
F ion has greater attraction to water
Average bond enthalpy
(2)
Breaking of 1 mole of bond in gaseous molecule
Explain why difficult to predict whether enthalpy change of solution become more or less exothermic down group for magnesium halide
(4)
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
Bidentate ligand?
(2)
Donates two lone pairs of electron and form 2 coordinate bonds to metal ion
1 important feature of fuel cell thats different from conventional storage cell
(1)
Fuel react with oxygen to give electrical energy
