Questions tagged [physical-organic-chemistry]

For questions about how organic molecules and reactions are investigated using physical experiments.

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Higher Experimental Optical activity compared to literature values [closed]

If you have a sample of an optically active substance it has a specific angle of rotation. Lets say the substance I produced had a value of 56 degrees but the literature value for my substance should ...
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What is the justification for using the Marcus rate equation to model charge transport in organic semiconductors?

I am trying to understand the history of how Marcus theory moved from describing electron exchange reactions in aqueous ionic solutions to also being applied to describe transport in organic ...
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What can we say about the dipole moment of terephthalic acid?

The dipole moment of quinol is not zero because it can exist in two different energetically favourable conformations. The weighted average is calculated to arrive a dipole moment of 1.6 D. According ...
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2answers
136 views

Why does the dipole moment of molecules go from positive to negative? [duplicate]

In physics the dipole moment is said to go from the negative to the positive pole, check for instance https://en.wikipedia.org/wiki/Electric_dipole_moment (Elementary definition). This makes sense ...
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1answer
69 views

Ratio of uncharged to charged side chains [closed]

The $\mathrm{p}K_\mathrm{a}$ of the side chain imidazole group of histidine is $6.0.$ What is the ratio of uncharged to charged side chains at $\mathrm{pH}~7?$ Here's my attempt to the solution: $$7 ...
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Volatility comparison for isomers of phthalic acid

All the atoms of these compounds are in a plane. o-phthalic acid can show extensive intra-molecular hydrogen bonding as well as inter-molecular hydrogen bonding. m-phthalic acid can show intra-...
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Enantiomeric excess catalysed

Enantiomeric excess is defined as $$ee = \frac{[R]-[S]}{[R]+[S]}$$ I found this problem in an IChO paper: "When using the enantiomerically pure (BINOL)Al(OiPr) as a catalyst for reduction of ...
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1answer
66 views

Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf? [closed]

I'm stumped by this question: Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf? I've thought that it might have something to do with how sun emits light ...
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2answers
45 views

Enzyme Kinetics

How come enzymes with a lower $K_\mathrm{m}$ are more easily saturated with substrate than an enzyme with higher $K_\mathrm{m}?$ Is it because enzymes with higher $K_\mathrm{m}$ are able to bind ...
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22 views

Thermodynamic data related to diazotization reaction

Is there any thermodynamic data available for diazotization of aniline and also for the reduction of the diazonium salt using sodium sulfite? I also want to know the heat of reaction for both the ...
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47 views

Why does the reduction of Dichromate to Chromium 2 need an acid? [closed]

The Ecell shows that Zn is enough. Then why, are both of them required? Also, can I use any acid ? Or only HCl + H2SO4
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1answer
169 views

Why do weak acids like ethanol not act as a strong base in water?

In water, ethanol has a $\mathrm{p}K_\mathrm{a} = 15.9$ which means that its $\mathrm{p}K_\mathrm{b}$ is $-1.9$. Which implies that all weak acids in water are in fact strong bases. But this is not ...
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Alkene production by dehydrohalogenation [closed]

What is the difference in the reaction mechanism when alkyl halides are reacted with aq.koh and alcoholic koh along with products
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1answer
32 views

Zinc and copper [closed]

Is potential energy and ionisation energy are same? Plz explain with respect to zinc Why zinc is undergoing oxidation when combined with with zinc. copper in electrochemical series
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Why do identical protons not couple with each other in 1H NMR? [duplicate]

So basically I'm wondering why the different protons in ...let's say trans-stilbene do not couple with each other. I'm aware of the fact that they are chemically and magnetically equivalent. They ...
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135 views

which one is the correct statement of “Law of definite proportion”? [closed]

according to my genius Teacher ' this law state that "the composition of a compound in terms of atoms (Not Mass) remains constant". His Proof: H2O and D2O are similar compounds (because H and D have ...
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Why does wood burn but not sugar?

Fundamentally, they're both carbohydrates, although the cellulose in wood is essentially polymerized glucose, which combined with its isomer fructose forms sucrose. So why does wood readily burn ...
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87 views

Number of configurations/states for electrons in orbitals

I'm performing complete active space calculations for the prediction of X-ray absorption L edge spectra. This involves an excitation from 2p orbitals to the 3d orbitals of the metal. For the ...
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2answers
712 views

How can isotope labelling be used to determine the mechanism of ether cleavage with hydrogen iodide?

When methyl tert-butyl ether (MTBE) is treated with one equivalent of hydrogen iodide, the ether C–O bond is cleaved. I read that if the oxygen in MTBE is isotopically labelled, it is possible to ...