REFLECTION ON PAPER 42 OCT/NOV 2021 by Pooganeswari Siteram Pillai

Chris JC2T

2022-03-05 08:44:19 UTC

Relevant topic: Further Aspects of Equilibria

Mechanism for Partition Coefficients and Solubility Product is used here.

Chris JC2T

2022-03-05 08:45:20 UTC

Relevant topic: Chemical Energetics

Mechanism for Lattice Energy and Born-Haber cycle is used here.

Chris JC2T

2022-03-05 09:00:40 UTC

Relevant topic: Quantitative Electrolysis and Chemical Energetics

Mechanism for quantitative electrolysis, entropy and Gibb's free energy.

Chris JC2T

2022-03-05 09:15:46 UTC

Relevant topic: Group 2 Metals

Properties and reactions of Group 2 metals and compounds.

Chris JC2T

2022-03-05 09:26:35 UTC

Relevant topic: Transition Metals

Properties and reactions of Complex ions, colors of complex ions.

Chris JC2T

2022-03-05 10:46:49 UTC

Relevant topic: Transition Metals and Electrochemistry

Colors of complex ions, Stability constant and how it works, and Electrode Potentials.

Chris JC2T

2022-03-05 12:47:01 UTC

Relevant topic: Benzene and its Compounds

Reactions and properties of benzene compounds, and how carbon NMR works.

Chris JC2T

2022-03-05 12:56:53 UTC

Relevant topic: Organic Nitrogen Compounds, Analytical Chemistry

Structure of Amino Acids, Mechanism of High-Resolution NMR, Mechanism of Mass Spectrum, Mechanism and Diagram of Electrophoresis

Chris JC2T

2022-03-05 13:02:01 UTC

Relevant topic: Benzene and its Compounds, Organic Compounds

Reactions to produce amines, basicity of amines.

Chris JC2T

2022-03-05 13:06:41 UTC

Relevant topic: Benzene and its Compounds, Organic Compounds

Diazotization, Reactions of Phenol and Acyl Chloride, Reactions of Ethanol

Ella JC2G

2022-03-06 10:13:25 UTC

S8 is atomised and added with 2 moles of electrons to form S2-. The dominant factor (ionic charge or ionic radius) can be determined by comparing the lattice energies of two compounds.

Ella JC2G

2022-03-06 10:13:49 UTC

The Kpc value is less than the predicted since the mixture is analysed immediately and might not have reached equilibrium. The common ion effect can be used to explain precipitation.

Ella JC2G

2022-03-06 10:14:08 UTC

Quantitative electrolysis involves calculation using Q = ne and Q = It to calculate an unknown variable. Gibbs free energy (ΔHr - TΔS) can be used to determine spontaneity of reactions, with negative values of it meaning that the reaction is spontaneous at a given temperature. For this particular reaction, it will not be spontaneous at any temperature since both ΔHr and - TΔS are positive, resulting in a positive Gibbs Free Energy.

Ella JC2G

2022-03-06 10:14:24 UTC

The higher decomposition temperature for two compounds can be determined by analysing the measure of ion polarisation, which is greater for smaller cations and larger anions, given that they have the same charge in both compounds. The solubility of hydroxides increases down the group as both LE and HE become less exothermic but the LE changes more dominantly.

Ella JC2G

2022-03-06 10:14:44 UTC

Ligand exchange colours and formulas must be remembered. The different colours seen are caused by the different energy gaps.

Ella JC2G

2022-03-06 10:14:59 UTC

Different equations from the data booklet are used for oxidation in different pH conditions. A negative Ecell indicates a non-feasible forward reaction.

Ella JC2G

2022-03-06 10:15:18 UTC

The reagents CH3COCl and AlCl3 cause the formation of an electrophile for electrophilic substitution. The conversion of compound Q into a dicarboxylic acid involves refluxing it with alkaline KMnO4 and acidified K2Cr2O7.

Ella JC2G

2022-03-06 10:15:32 UTC

Identification of amino acids using a proton NMR spectrum can be done by analysing the multiplicity, number of peaks, and whether they correspond to that of the compound. The distance travelled in an electrophoresis experiment depends on charge and mass.

Ella JC2G

2022-03-06 10:15:44 UTC

Basicity of the compounds can be determined by their ability to accept a H+ atom, and how the groups attached to the N atom affects its electron density.

Ella JC2G

2022-03-06 10:15:55 UTC

The coupling of benzenediazonium salt with phenol involves the triple bond turning into a double bond, and the two rings joining with N=N in between.

Angela JC2G

2022-03-06 14:04:49 UTC

Lattice energy is affected by ionic radius and charge. A greater charge will result in a more exothermic lattice energy, while a greater ionic radius will result in a less exothermic lattice energy. For NaCl and RaS, the dominant factor is ionic charge, so RaS has a more exothermic lattice energy.

Angela JC2G

2022-03-06 14:06:13 UTC

Value for Kpc may be less as the mixture is analysed immediately and not allowed to reach equilibrium. Common ion effect shifts the position of equilibrium to the left, hence producing more PbI2(s), and a yellow ppt is seen.

Angela JC2G

2022-03-06 14:07:42 UTC

Quantitative electrolysis uses Q=ne and Q=It. When temperature is increased for a reaction with + enthalpy and - entropy, -TS becomes more positive, so G becomes more positive and the reaction becomes less spontaneous.

Angela JC2G

2022-03-06 14:10:15 UTC

Ion polarization is affected by ionic radius. Larger ions will have less polarizing power, so Sr(NO3)2 is more thermally stable than Mg(NO3)2. Going down the group, solubility of hydroxides increases. Mg(OH)2 is less soluble, and Sr(OH)2 is more soluble. Lattice energy decreases more compared to the enthalpy of hydration, so enthalpy of solution becomes more negative. Thus, Sr(OH)2 is more soluble.

Ashley JC2G

2022-03-06 14:11:38 UTC

I need to memorise the ligand exchange colours and reactions!

Finally understood the generic question for colour change/observation of colours questions

'd-orbitals split to a number of non-degenerate d-orbitals'

electrons are excited to another level, absorb light energy/frequency. colour observed is complementary of the colour frequency absorbed

Angela JC2G

2022-03-06 14:11:50 UTC

Recalled ligand exchange reactions and colour changes. A change in colour is due to changes in the d-orbital splitting.

Angela JC2G

2022-03-06 14:14:29 UTC

A positive Kstab value means that the product is more stable. A positive electrode potential value means that it is a feasible forward reaction.

Angela JC2G

2022-03-06 14:15:58 UTC

COOH is an electron withdrawing group so it directs position 3. The reagent for the oxidation of compound Q is alkaline KMnO4 which is then acidified and boiled.

Angela JC2G

2022-03-06 14:18:54 UTC

Mixture of amino acids can be maintained at a certain pH with a buffer solution during electrophoresis. Charge and relative molecular mass affects the distance travelled by an amino acid. An amino acid with a greater charge and smaller Mr will travel further.

Angela JC2G

2022-03-06 14:20:55 UTC

Recalled different ways and reagents to prepare amine. Basicity depends on the availability of the lone pair of electrons to accept H+. Butylamine has an e- donating alkyl group, making N more ready to bond with a H+. Phenylamine is weaker as the lone pair of electrons in it overlaps with the benzene ring and becomes delocalised.

Angela JC2G

2022-03-06 14:22:51 UTC

Recalled the different equations of phenol. Ethanol does not react with NaOH, and if ethanol was to react with the COCl-C6H4-COCl, concentrated H2SO4 will be needed.

Ashley JC2G

2022-03-06 14:26:33 UTC

K_stab equation goes by every normal formula: productsⁿ/ reactantsⁿ, but because in this case, water is infinite in a solution, so, therefore, H₂O is not accounted for in the formula
When calculating E⁰ values, make sure that the equations are rewritten correctly. In this case, with [Co(NH3)6]
²⁺oxidised, and O₂ reduced. As a result, the E^o values should also be flipped around (x -1)
Even when you need to multiply reactants in order to properly cancel out electrons, etc. the E⁰ do not change.
If in acidic conditions, make sure H+ is in the equation somehow??? If alkaline, OH- is used instead.
As long as E⁰ value is above 0, then the reaction is feasible/possible.

Ashley JC2G

2022-03-06 14:57:11 UTC

Can i just flex the fact that I got the number of peaks questions right first try, even that asymmetric looking structure😤 took me 20 mins but we're not talking abt that

remember that in heavy water (D2O), the N-H bond, and O-H bond (even the one in COOH group!), will disappear/will not appear as a peak in the graph.
revise distinguishing how many peaks a molecule would have, and counting how many neighbours -1 for the splitting T^T ++ and also distinguishing where the peaks are and their values
calculate each 'arm' of a molecule before adding it all up, it makes it easier to guess which m/e value belongs to what later
don't forget that not only is it a POWER supply, it's a DC power supply
filter paper must be soaked in buffer solution!

Thomson JC2T

2022-03-07 06:07:41 UTC

Lattice energy and enthalpy calculation

Thomson JC2T

2022-03-07 06:08:14 UTC

Kpc and Ksp. Common ion effect.

Thomson JC2T

2022-03-07 06:08:49 UTC

Stochiometry, entropy and gibbs free energy.

Thomson

2022-03-07 06:09:55 UTC

Trend in group 2 metals, polarisation of bond (how it affects stability), stochiometry

Thomson JC2T

2022-03-07 06:10:39 UTC

reaction of phenol and how it compares to ethanol

Thomson JC2T

2022-03-07 06:16:14 UTC

Formation of amine and their basicity

Thomson JC2T

2022-03-07 06:17:36 UTC

Isomerism, hydrogen NMR, splitting and electrophoresis of amino acid

Thomson JC2T

2022-03-07 06:18:55 UTC

Carbon environemnts, directing groups, electrophillic substitution in Benzene compounds, oxidation

Thomson JC2T

2022-03-07 06:20:20 UTC

Kstab, Ecell calculation, interpretation of Ecell value

Thomson JC2T

2022-03-07 06:21:26 UTC

Ligands, ligand exchange, origin of colour in transition metal compounds