Chemistry

Question 1

What factors can influence a reaction rate in a solid-solid reaction?

Answer 1

Temp, Concentration, light, catalyst is present, amount of interfaces

Question 2

Why are third order reactions not common?

Answer 2

Because 3 reactants would have to spontaneously collide together and this is very unlucky.

Question 3

What is Dalton’s law of partial pressure?

Answer 3

The total pressure of a gas mixture is = to the sum of the partial pressures of each individual gas.

Question 4

How can you experimentally determine an enthalpy change

Answer 4

Calorimeter experiment and use of
∆H = M x C x ∆Tn

Question 5

If the dehydration of a long chain alcohol was limited by equilibrium how could you drive the reaction towards the right-hand side?

Answer 5

Adding more reactants should drive the reaction to the right base on le chairs principle.

Question 6

For F, what possible quantum numbers can a valence electron have?

Answer 6

principal Q number n = 2
Angler L = 1 describes the p subshell, 0=s and 2=d subshell
magnetic ml = -1,0,+1 but is overall 0
spin ms = - 1/2 because second half og shell filled

Question 7

What is the difference between a cubic and a tetragonal unit cell?

Answer 7

cubic - all 3 axis’s are same length and all perpendicular to one another.
tetragonal - 2 of the 3 axis are the same length and all perpendicular to one another.

Question 8

What sort of techniques could you use to distinguish between the surface and bulk of a solid?

Question 9

Why do transition metal complexes often have vivid colours?

Answer 9

excitation of an electron from a lower-energy d orbital to a higher-energy d orbital, which is called a d–d transition

Question 10

If you were to make up a 1 mol L-1 solution of sodium hydroxide (40 g in 1 L). What would the concentration of ‘NaOH’ be in ppm?

Answer 10

1 mols x 40 mass g = 40 g/L
40 x 1000 = 40000 ppm

Question 11

If you follow an acid base titration by conductivity, why can you not ‘miss the end point’?

Answer 11

because the its the lost vaule of the conductivity, after a amount of base add the conductively will increase again, this is because there is an execs of ion in the solution.

Question 12

What kind of detectors might be used with HPLC and why?

Answer 12

UV detector because of its eases and high sensitivity, quantitative
Vis

Question 13

explain the stereochemistry.

Answer 13

attack 2 different positions to get cis-trans isomers

Question 14

What is a carbocation and how could you stabilise one?

Answer 14

C+ HX3 and add methyl groups to C+ (CH3)3
or react with OH.

Question 15

Why are alkynes quite reactive?

Answer 15

because they have 2 Pie bonds more electron density so can react faster

Question 16

when wanting T ΔG=0 so T=ΔH/ΔS

Answer 16

. + ΔS and +ΔH the reaction is spontaneous at high temp but not at low temp.
. +ΔH and -ΔS reaction is not spontaneous at all temps
. -ΔH and +ΔS spontaneous at all temps
. -ΔH and -ΔS is not spontaneous at high temp but is at lower temps

Question 17

How are E°cell and ΔG related.

Answer 17

ΔG = -z F x Ecell

Question 18

what is its wavelength range?

Answer 18

Visible light - 740nm - 390nm

Question 19

what is an Sn1 reaction?

Answer 19

have more stable cation draw

Question 20

what is an Sn2 reaction?

Answer 20

Attacking group attacks from the back (180 degrees) away from the leaving group.
its Biomolecular

Question 21

what is a unit cell

Answer 21

smallest possible repeat unit of a crystal structure in 3D that shows the full symmetry of the structure.

Question 22

what are the 7 unit cell shapes?

Answer 22

1. cubic
2. tetragonal
3. othrombotic
4. monoclinic
5. triclinic
6. hexagonal
7. rhombohedral

Question 23

what is a lattice point?

Answer 23

points with identical environments

Question 24

how to draw Lewis structure?
give examples
H-Br
2H - S
N-N

Answer 24

1. Count Electrons
2. draw possible structures
3. add electrons evenly to outer atoms, then anything left over put in the middle atoms
4. work out formal charges = lowest best
5. q = V - B - E
   v = valance e-
   B = bonds
   E - left over electrons

Question 25

Diels-Alder reaction draw
1. butadiene + ethene
2. butadiene + acetylene

Answer 25

give a range of 6 member rings
1. one double bond in the ring
2. two double bond in the ring

Question 26

what is a grignard reagent and give a type of mechanisum.

Answer 26

A Grignard reagent is an organomagnesium halide having a formula of RMgX, where X is a halogen (-Cl, -Br, or -I), and R is an alkyl or aryl (based on a benzene ring) group. To initiate a Grignard Reaction, a Grignard reagent is added to a ketone or aldehyde, to form a tertiary or secondary alcohol.

Question 27

1st law of thermodynamics

Answer 27

∆U= w + q
∆U = change in internal energy
w = heat added
q = work done by the system

Question 28

2nd law of thermodynamics

Answer 28

The second law states that if the physical process is irreversible, the combined entropy of the system and the environment must increase. The final entropy must be greater than the initial entropy for an irreversible process: Sf > Si (irreversible process)

Question 29

draw e1 reaction

Question 30

draw an e2 reaction

Question 31

first order graph

Question 32

second order graph

Question 33

draw FES set up

Question 34

d-d orbital splitting

Answer 34

3d splitiing - High spin place as many electrons in each orbital as possible before you pair up.
low spin- place as many electrons as possible on t2g level before going up to the eg level
3 levels in t2g
2 levels in eg

Question 35

electronphilic and nucleophilic aromatic substitution

Question 36

jahn teller disortion

Answer 36

reduces its symmetry and energy. This distortion is typically observed among octahedral complexes where the two axial bonds can be shorter or longer than those of the equatorial bonds. This effect can also be observed in tetrahedral compounds. This effect is dependent on the electronic state of the system.

Question 37

diamagnetic
paramagnetic

Answer 37

• no unpaired electrons
• unpaired electrons

Question 38

AX2
AX3
AX4
AX6

Answer 38

2 - linear - 180
3 - trigonal -120
4 - tetrahedral -109.5° angles
6- Octahedral - 90

Question 39

what are the differences between sn1 and sn2

Answer 39

sn1: unimolecular (only one reactant), 2 step, rate - first order, proportional to [substrate].

sn2: bimolecular (more than one reactant), 1 step, rate - first/second order - proportional to [substrate] [Nu-]/

Question 40

how does NMR work: 1.talk about the over all, 2.shift, 3.Equivalent and non-equivalent protons, 4.N plus 1 rule.

Answer 40

1.transfer of energy is possible from base energy to higher energy levels when an external magnetic field is applied. The transfer of energy occurs at a wavelength that coincides with the radio frequency. Also, energy is emitted at the same frequency when the spin comes back to its base level
2.Shield = upfield
DE shielded = downfield
3.Protons in the same chemical environment have the same chemical shift - chemically equivalent , Chemically non- equivalent is the opposite.
4.N (neighbouring protons split the signal of the observed proton into) N +1 lines.

Question 41

benzene(R group @ top C1) which are the Ortho meta and para positions?

Answer 41

Ortho C2,6
meta C3,5
para C4

Question 42

Draw eclipsed and staggered conformations.

Answer 42

eclipsed: H next to each other
Staggered: H spread inbertween each other

Question 43

briefly explain XRD

Question 44

Draw cyclohexane

Answer 44

axctoral X point up
equatorial X point along