flame? To answer that question, we need to look at
Section 9 of the SDS for methanol (see “Highlights
from ‘Section 9: Physical Data’ ” below).
If you examine the data above (which is only a small portion
of what is contained in the SDS for this section), you will notice
the terms “flash point” and “autoignition temperature.” The
flash point is the temperature at which the vapors above a liquid ignite if an outside ignition source, such as a spark or flame,
For example, if a beaker of methanol is at a temperature
below its flash point, you cannot set it afire, even if you put an
open flame to it. So, at 10 °C and below, methanol will not catch
on fire. But once it reaches 11 °C—its flash point—you can set
it on fire if you light it.
As a liquid warms, the average kinetic energy of its molecules
increases. Because more molecules
have enough kinetic energy to escape
the attractive forces holding them
together in the liquid phase, its
evaporation rate increases, producing more vapor. The flash point
occurs when a sufficient concentration of vapor has accumulated
above the liquid, which, in combination with oxygen, will burn if
ignited. Remember: Only vapors burn,
When the flash point is reached, the vapors
will ignite, but the fire will not be sustained,
because there is not enough vapor present to
sustain combustion. This ignition is still very
dangerous, as a quick burst of flame can produce severe burns, and if other combustible
substances are nearby, they can also catch on fire.
A more useful value is the fire point, which is the point at which a
flammable liquid will not only catch on fire if lit but will also keep burning for five seconds. The fire point is typically only a few degrees higher
than the flash point.
If methanol is at or above its fire point, it will continue to burn when
lit. Under most laboratory conditions, methanol will be above its fire
point, so when lit, it will continue to burn. Although the fire point is not
included on the SDS, it is important to know how it differs from the
The autoignition temperature is the temperature at which a substance will burst into flames without an outside ignition source, such
as a spark or a flame. At the autoignition temperature, spontaneous
combustion occurs. According to the SDS for methanol, the autoignition temperature is 464 °C. So, when the methanol was poured onto the
smoldering cotton balls, if they were at a temperature above 464 °C, the
methanol would instantly burst into flames on contact. Substances do
not need flames to catch on fire—they only need a sufficient amount of
heat along with air.
Considering the number of students who take high school chemistry,
the number of students who were involved in accidents in a chemistry Answers to quiz on p. 6: 1. e, 2. c, 3. g, 4. i, 5. d, 6. a, 7.f, 8. b, 9. h
class is relatively small, and of the accidents that occur, most are
The number of students injured in science labs is smaller than
those injured in sports. This good safety record is due to science
teachers being vigilant about enforcing safety rules in the laboratory. So,
the next time your chemistry teacher tells you to put your goggles on,
make sure you comply, as he or she is only looking out for your safety.
While every accident in the chemistry lab cannot be avoided, the
recent incidents with methanol likely could have been avoided, had the
experimenters familiarized themselves with the safety information contained in an SDS. Anytime chemicals are used in the laboratory, there
are risks involved, but these risks can be minimized by understanding
the chemicals used in an experiment. It is often said that a little knowledge is a dangerous thing, but when it comes to chemicals, a little
knowledge can save your life!
Tinnesand, M. Material Safety Data Sheets: Passports to Safety? ChemMatters,
Oct 2006, pp 18–19.
The ANSI Standardized MSDS Format. Ben Meadows Tech Facts, Document No.
History of the MSDS. James R. Macdonald Laboratory, July 14, 2009:
http://jrm.phys.ksu.edu/safety/kaplan.html [accessed Sept 2015].
Improving Chemistry Demonstration Safety. Chemical & Engineering News,
Nov 17, 2014: http://cen.acs.org/articles/92/i46/Improving-Chemistry-
Demonstration-Safety.html [accessed Sept 2015].
Brian Rohrig is a science writer who lives in Columbus, Ohio. His most recent
ChemMatters article, “Eating with Your Eyes: The Chemistry of Food Colorings,”
appeared in the October/November 2015 issue.
Highlights from "Section 9: Physical Data" ÜMelting point: -97.8 °C ÜFreezing point: -97.6 °C ÜBoiling point: 64.7 °C ÜFlash point: 11 °C ÜAuto-ignition temperature: 464 °C
If a fire occurs in a lab, it is important to know that different types of fire extinguishers are used for different types of fires. In the United States, fires are classified depending on the materials
that catch fire. Methanol combustion is an example of a Class B fire.
should be able to
extinguish this kind
of fire, but to make
sure, read the label
on the fire extinguisher.
ChemMatters | DECEMBER 2015/JANUARY 2016 7
of Fires Types of Fires Picture Symbol
Wood, paper, cloth, trash
& other ordinary liquids.
Gasoline, oil, paint and
other flammable liquids.
May be used on fires
involving live electrical
danger to the operator.
and combustible metal
In case of a lab fire