how can methanol be highly flammable if its boiling point is 64.7 degrees Celsius?HELP!?

Question

since methanol has the lowest molar mass I do understand that it is the alcohol that evaporates easier than say ethanol or propanol. Our body temperature never exceeds 40 degrees celsius. yet they say that it is the vapor that causes the nausea and blindness. I dont see how methanol can go from liquid to vapor. PLEASE HELP ME

Answer 1

Methanol fums are not as toxic as ingesting it (see second paragraph). Once in the body methanol is converted to formaldehyde by the same enzyme that breaks down ethanol (drinking alcohol). This is quickly converted into formaldehyde which by various methods denatures proteins and interrupts metabolic pathways.

To answer your other question, at 40 degress C (or body temp which is 37 deg C) methanol will still have a significant vapor pressure, much hgher than water would have. That's one of the reasons its so easy to smell alcohol and one the reason it can be dangerous inhaled. See second reference.

Vapor pressure of methanol at 37.0 ºC : 230.76 [mmHg]

From the website below:

Formate is assumed to be the toxic agent.

In the first step of its degradation, methanol is transformed to formaldehyde via the enzyme alcohol dehydrogenase (ADH). This reaction is slower than the transformation of formaldehyde to formic acid, which may explain the reason for the latency of symptoms between ingestion and effect. The half-life of formaldehyde is estimated to be 1-2 minutes (Jacobsen and McMartin, 1986).

The eye damage caused by methanol has been well described. However, the mechanism behind this phenomenon is not well understood. The major damage occurs at the retrolaminar optic nerve with intra-axonal swelling and organelle destruction. Little to no change is seen in the retina (Casarett et al, 1996).

Methanol also affects the basal ganglia. With severe intoxication, both hemorrhagic and nonhemorrhagic damage of the putamen occur commonly. This was described initially in 1953, although the clinical syndrome associated with this lesion was not described until more recently (Phang et al, 1988).

Parkinsonism and other dystonic/hypokinetic clinical pictures also can occur. The predilection for and mechanism of toxicity to the putamen are not understood. Some postulate that striatal neurons have a varying sensitivity to toxic metabolites of methanol. However, this remains to be proven (LeWitt and Martin, 1988). In addition, cases of axonal polyneuropathy in association with chronic exposure have been reported (Hageman et al, 1999). Anterior horn cell loss also has been documented.

Answer 2

Note that boiling point is the one required to convert LIQUID to GAS. Methanol has got only one -OH group, lower than any other alcohol. The available number of water molecules from methanol is therefore 2 from 2 moles of methanol. Therefore, the amount of heat required to break just a single C-OH bond is less, when compared to that required to break such molecule of water, whose boiling point is 100 degrees Celsius. The vapours that come out from an open methanol container are of probable methane molecules, whose inert nature, just like that of rare gases, make them rare to content because all the 4 valencies of the symmetric Carbon atom are equally supplied with 4 identical Hydrogen atoms.

Answer 3

So you think that below its own boiling point, a liquid will not evaporate? If that were so, puddles would never dry up. Why should a bunch of molecules all choose to stay in the liquid phase rather than jumping off into the atmosphere?
The boiling point of a liquid under standard conditions is merely the temperature at which its vapour pressure becomes equal to the pressure of the atmosphere. Below its boiling point, its vapour pressure is less than one atmosphere, but it is certainly not zero. It will still evaporate gradually.