아레니우스식

$$
k = Ae^{-\Delta E/RT}
$$

화학평형 깁스에너지

quilibrium

Chemical equilibrium is a state in which there is no net change in the concentration of reactants and products because the forward and reverse reactions are occurring at the same rate and the Gibbs free energy value is at its minimum. 

The Gibbs free energy change of a reaction tells us what the concentration of reactants and products will be at equilibrium. For a general reaction of a moles of A, b moles of B and c moles of C combining to form n moles of N, m moles of M, and o moles of O...



If the reaction is not at equilibrium, it will proceed in the forward or reverse direction to the minimum value of the Gibbs free energy. At that point, there is no further change in the Gibbs free energy (G = 0) and the reaction is at equilibrium.

벤젠 엠오

B.                 MOLECULAR ORBITAL REPRESENTATION OF BENZENE (MO THEORY)

The bond angles of 120° in benzene suggests that C atoms are sp² hybridised.  An alternative representation therefore starts with a planar framework and considers overlap of the p orbitals (p electrons).

(Simple MO rules)
Mix n x p atomic orbitals np molecular orbitals!
Remember ethene? (p 26)

The exact calculation of their position (shown below) is beyond our discussion.

Each MO can accommodate 2 electrons, so for benzene we see all electrons are paired and occupy low energy MO’s (bonding MO’s).  All bonding MO’s are filled.  Benzene is therefore said to have a closed bonding shell of delocalised p electrons and this accounts in part for the stability of benzene.

low spin complexes

Figure 9 d orbital splitting in an octahedral complex

The electrons can actually be distributed in two ways among the two sets of orbitals for complexes with 4,5,6 or 7 d electrons: occupying the lowest orbitals (low spin) or spread over both sets of orbitals (high spin). As you can see in Figure 9 (a) and (b) we have two different configurations for iron(II), which has 6 d electrons - (a) has no unpaired electrons and is thus non-magnetic and is known as low spin; (b) has four unpaired electrons and is magnetic and is known as high spin.
The magnitude of the energy gap between the two levels, , which is known as the 'ligand field splitting', determines whether we get the high spin or low spin form. If is small than the lowest energy state is when electrons are distributed over both levels and we get high spin complexes. If is large then the lowest energy state is when electrons occupy the lowest level preferentially and low spin complexes result.
The size of the splitting, , for a given metal depends on its oxidation state (charge) and on the nature of the ligand bonded to the central metal. is larger for +3 than for +2 ions, and increases as the strength of bonding between the ligand and metal increases. Thus water is a weak ligand and produces a small ligand field splitting and (usually) high spin complexes. Cyanide, on the other hand, bonds very strongly to transition metal ions with a mixture of å and ã bonding and usually produces low spin complexes (see Figure 9). Common ligands can be arranged in order of the splitting they produce and this series is known as the spectrochemical series (Table 1).

Calculating solubilities from solubility products

Calculating solubilities from solubility products

Reversing the sums we have been doing isn't difficult as long as you know how to start. We will take the magnesium hydroxide example as above, but this time start from the solubility product and work back to the solubility.

If the solubility product of magnesium hydroxide is 2.00 x 10^-11mol³ dm^-9 at 298 K, calculate its solubility in mol dm^-3 at that temperature.

The trick this time is to give the unknown solubility a symbol like x or s. I'm going to choose s, because an x looks too much like a multiplication sign.

If the concentration of dissolved magnesium hydroxide is s mol dm^-3, then:

[Mg²⁺] = s mol dm^-3

[OH^-] = 2s mol dm^-3

Put these values into the solubility product expression, and do the sum.

CH3NaO

•   http://www.chemspider.com/Chemical-Structure.29033.html
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Sodium Methoxide

• ChemSpider ID: 29033
• Molecular Formula: CH₃NaO
• Average mass: 54.023701 Da
• Monoisotopic mass: 54.00816 Da
• Systematic name
  Sodium methanolate
• SMILES and InChIs

  SMILES:

  [Na+].[O-]C
  

  Std. InChI:

  InChI=1S/CH3O.Na/c1-2;/h1H3;/q-1;+1
  

  Std. InChIKey:

  WQDUMFSSJAZKTM-UHFFFAOYSA-N
• Cite this record

nernst equation

Standard Electrode Potentials

In an electrochemical cell, an electric potential is created between two dissimilar metals. This potential is a measure of the energy per unit charge which is available from the oxidation/reduction reactions to drive the reaction. It is customary to visualize the cell reaction in terms of two half-reactions, an oxidation half-reaction and a reduction half-reaction.

Reduced species -> oxidized species + ne-	Oxidation at anode
Oxidized species + ne- -> reduced species	Reduction at cathode

The cell potential (often called the electromotive force or emf) has a contribution from the anode which is a measure of its ability to lose electrons - it will be called its "oxidation potential". The cathode has a contribution based on its ability to gain electeons, its "reduction potential". The cell potential can then be written
E_cell = oxidation potential + reduction potential If we could tabulate the oxidation and reduction potentials of all available electrodes, then we could predict the cell potentials of voltaic cells created from any pair of electrodes. Actually, tabulating one or the other is sufficient, since the oxidation potential of a half-reaction is the negative of the reduction potential for the reverse of that reaction. Two main hurdles must be overcome to establish such a tabulation

1. The electrode potential cannot be determined in isolation, but in a reaction with some other electrode.
2. The electrode potential depends upon the concentrations of the substances, the temperature, and the pressure in the case of a gas electrode.

In practice, the first of these hurdles is overcome by measuring the potentials with respect to a standard hydrogen electrode. It is the nature of electric potential that the zero of potential is arbitrary; it is the difference in potential which has practical consequence. Tabulating all electrode potentials with respect to the same standard electrode provides a practical working framework for a wide range of calculations and predictions. The standard hydrogen electrode is assigned a potential of zero volts.
The second hurdle is overcome by choosing standard thermodynamic conditions for the measurement of the potentials. The standard electrode potentials are customarily determined at solute concentrations of 1 Molar, gas pressures of 1 atmosphere, and a standard temperature which is usually 25°C. The standard cell potential is denoted by a degree sign as a superscript.

E°Cell

Measured against standard hydroden electrode. Concentration 1 Molar Pressure 1 atmosphere Temperature 25°C

The example below shows some of the extreme values for standard cell potentials.

Cathode (Reduction) Half-Reaction	Standard Potential E° (volts)
Li+(aq) + e- -> Li(s)	-3.04
K+(aq) + e- -> K(s)	-2.92
Ca2+(aq) + 2e- -> Ca(s)	-2.76
Na+(aq) + e- -> Na(s)	-2.71
Zn2+(aq) + 2e- -> Zn(s)	-0.76
Cu2+(aq) + 2e- -> Cu(s)	0.34
O3(g) + 2H+(aq) + 2e- -> O2(g) + H2O(l)	2.07
F2(g) + 2e- -> 2F-(aq)	2.87

The values for the table entries are reduction potentials, so lithium at the top of the list has the most negative number, indicating that it is the strongest reducing agent. The strongest oxidizing agent is fluorine with the largest positive number for standard electrode potential. The link below takes you to a more extensive table.

Table of Standard Electrode Potentials

Useful applications of the standard electrode potentials include the following.

Strengths of oxidizing and reducing agents

Electrode potentials under non-standard conditions

Potentials for voltaic cells

Relationship to Gibbs free energy

Relationship to equilibrium constants

산 해리도

착이온

2. 착화합물

중심 금속 이온에 비공유 전자쌍을 가진 분자나 음이온 (리간드)이 배위 결합하여 이루어진 이온을 착이온이라 하며, 착이온이 들어 있는 화합물을 착화합물이라고 한다.

여기서 착이온의 전하량은 착이온과 결합한 -1가의 염화이온이 두 개이므로 +2가임을 알 수 있고 중심 금속 이온의 전하량은 착이온내에 있는 총 전하량이 +2가 되려면 +3이란 것을 알 수 있다.

 착이온의 생성

 리간드(ligand)

착이온의 구조는 중심에 금속 이온이 있고 이것을 둘러싸고 있는 분자나 이온은 금속 이온에 비공유 전자쌍을 제공하여 배위결합을 형성하는데, 이러한 분자나 이온을 리간드라고 한다. 따라서 리간드로 작용하는 분자나 이온은 반드시 중심원자에 비공유 전자쌍을 가지고 있어야 한다.

 리간드로 작용할 수 있는 분자 및 이온

비공유 전자쌍을 가지고 있는 분자나 음이온만이 리간드로 작용할 수 있다.

  배위수

하나의 중심 원자에 결합되어 있는 리간드의 수를 배위수라고 한다. 가장 흔한 배위수는 2, 4, 6인데, 배위수에 따라 착이온의 입체 구조가 달라진다.

 착이온의 구조

중심 이온	배위수	착이온	입체 구조
Ag＋	2	[Ag(NH3)2]＋	선형
Cu2＋	4	[Cu(NH3)4]2＋	평면 사각형
Zn2＋	4	[Zn(NH3)4]2＋	정사면체
Co3＋	6	[Co(NH3)6]3＋	팔면체형

선형	평면 사각형	정사면체	팔면체형

  착이온의 이성질체

착이온이나 착화합물에서는 같은 원자들이 서로 결합되어 있으나, 공간에서 배열되는 방법이 서로 다르게 되어 나타나는 기하이성질체이가 존재한다. 기하이성질체에는 시스 이성질체(cis isomer)와 트렌스 이성질체(trans isomer)가 존재하며, 시스라는 말은 "같은 쪽에"라는 뜻이고, 트렌스라는 말은 "반대쪽에" 라는 뜻을 나타낸다. 배위수가 4인 착이온 혹은 착화합물 중 사각평면 구조를 가지는 것은 기하이성질체를 가지나 정사면체형은 기하이성질체를 가지지 않는다. 배위수가 6인 착이온 혹은 착화합물도 기하이성질체를 갖는다.

 착이온의 종류

킬레이트(chelate) 한 개의 리간드가 금속이온과 두 자리 이상에서 배위 결합을 하는 경우 여러 자리 리간드라 하며, 이렇게 하여 만들어진 고리 모양의 착이온을 킬레이트라고 한다. 킬레이트라는 것은 새우나 게의 집게를 의미하는 그리이스어의 chela라는 단어에서 유래한 것인데, 오른쪽 그림과 같이 그모양이 꼭 게가 집게로 금속이온을 잡고 있는 것과 같은 모양을 취하기 때문에 이렇게 불리워지게 되었다. [그림] EDTA : 미량의 금속 이온을 분석하는 시료로 사용되는 킬레이트

4-bromo-1-butene

http://www.chemsynthesis.com/base/chemical-structure-38256.html Registry Numbers
Cas Number: 5162-44-7 EINECS Number: 225-937-4 MDL Number: MFCD00000258
InChIKey:	DMAYBPBPEUFIHJ-UHFFFAOYAD
Smiles:	BrCCC=C
Chemical Structure
Synthesis (Preparation) Reference
Tetrahedron Letters, 25, p. 251, 1984 DOI: 10.1016/S0040-4039(00)99853-8