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Physics, 05.07.2019 06:10 burnsmykala23

When a flammable liquid such as gasoline ignites, the substance actually burning is vapor that is generated from the liquid. if the concentration of the vapor in the air about the liquid exceeds a certain level called “lower flammability limit” the vapor will ignite if it is exposed to a spark or another source of ignition. once ignited the heat released is likely to cause additional vaporization of the liquid and the resulting fire may continue until all the combustible material has been consumed.(a) the flashpoint is defined as the minimum temperature at which a flammable liquid or volatile solid gives of sufficient vapor to form an ignitable mixture with air near the surface of the liquid or within a vessel. for example the flashpoint of normal octane is 13°c at 1 atm pressure which means that dropping and match into an open container of octane is likely to start a fire in the laboratory but not outside on a cold winter day (caution: do not try suppose you are keeping two solvents in your laboratory, one with the flashpoint of 15°c and the other with the flashpoint of 75°c. how do these solvents differ from the standpoint of safety? what differences, if any, should there be in how you treat these solvents? (b) the lower flammability limit (lfl) of methanol in air is six more percent. calculate the temperature at which is saturated methanol air mixture at 1 atm would have a composition corresponding to the lfl. what is the relationship of this value to the flashpoint, and what value would you assign the flashpoint of methanol? (c) give reasons why it would be unsafe to maintain an open container of methanol in an environment below the lfl. (i. e., the value calculated in part (b)) if there are ignition sources nearby. list common ignition sources that may be found in a laboratory.

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