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CO & Smell

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They are thereforeknown as chemicalsenses. The genesis ofthe perception of taste

or smell isintermolecularinteraction rather thaninteraction of moleculeswith electromagnetic

radiation (vision) orpressure differences(sounds).

evolution it has keptits connections withthose parts of our

brain which sort ouremotionalresponses.

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To be smelly, asubstance must beeither a sufficientlyvolatile liquid/solid or agas. It must be able to

release into air aroundus enough number ofmolecules/particleswhich can stimulate oursensory receptors.

Ionic substances likecommon salt andminerals rocks havetherefore no odour at all.

Molecules of an odouroussubstance present in air,when swept into ournostrils, dissolve into themucus fluid surrounding thecilia to cause the cells to

stimulate the neurons.

The sensory receptors thenfire off electrical signals tothe two olfactory bulbs inthe brain. It is in the brain

that these signals areprocessed to generate theperception of a particularsmell.

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21,000,000,000

molecules

Thus unless acertain optimumnumber of

molecules of asubstance enterour nostrils we donot perceive a

smell

1/460,000,000 of amilligram of amercaptan, (a

group of odorouschemicals)contained in a whiffof air is sufficient

to elicit a strongodour or . . .

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Some believed that thesmell of a chemicaldepends on propertiessuch as the shape,chemical structure or

electrical charge of itsmolecules.

But recently, scientistshave identifiedcompounds which arestructurally totally

unrelated but still havesimilar odours.

Fruity

Bitter almonds

Rotten eggs

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The current suggestion is that thepresence of certain vibrationalbands in the infra red spectrum of

the substance, may stimulate aparticular odor.

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SO, Whats the deal with Carbon Monoxide?!

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CO is not an acidic oxide [unlike CO2] it isonly slightly soluble in H2O. The use ofmolecular oxygen as an electron acceptor

is why it really isnt soluble in H2O.

Lipids closely relate to hydrocarbons but

have other atoms which limit solubility.

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The 2nd Law of Thermodynamics states that spontaneous run-down hillincreasing entropy or disorder.

Van der Waal force:

Carbonic acid => weak

[ H2CO3 ]

[ CO2 + H2O ]

Metabolic release of CO2 reduces pH in the surrounding cellular fluids whichmust be buffered in order to proceed. This is accomplished by the hemoglobinprotein.

It burns readily in Oxygen. It is used in organic synthesis & production ofhydrocarbon fuels.

Stimuli detected by the olfactory system (odors,smells) are volatile substancesin the air sensitive enough to detect 1-part in 50-billionths of air; thusly it isadded to odorless natural gas so we may detect gas leaks.