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.
Under most ambient 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 flash point.
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 auto-ignition temperature, spontaneous combustion occurs. According to the SDS
for methanol, the auto ignition 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 chemistry or
see chemistry demonstrations, the number of students who
are involved in such accidents is relatively small, and of the
accidents that occur, most are relatively minor.
The number of students injured in science labs is smaller
than those injured in sports. This good safety record is due to
vigilance about enforcing safety. So, the next time you do a
chemistry demonstration, make sure you follow all safety protocols—use well-established procedures, make sure you and
your audience are wearing googles and any other appropriate
protection, and read up on all the hazards associated with your
chemicals and equipment. You can find recommendations and
other information for demos at www.acs.org/safety.
The recent incidents with methanol likely could have been
avoided, had the experimenters used the information in the
SDSs appropriately. Anytime chemicals are used, there are risks
involved, but these risks can be minimized by understanding
the chemicals involved. By keeping your demos safe, you
and your audience can focus on the excitement and fun of
chemistry, not the fear of injuries! .
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.
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. 250:
format_250.pdf [accessed Sept 2015].
History of the MSDS. James R. Macdonald Laboratory, July 14, 2009:
jrm.phys.ksu.edu/safety/kaplan.html [accessed Sept 2015].
Improving Chemistry Demonstration Safety. Chemical & Engineering
News, Nov 17, 2014: cen.acs.org/articles/92/i46/Improving-Chemistry-
Demonstration-Safety.html [accessed Sept 2015].
Safe Transportation Recommendations for Chemicals Used in
Demonstrations and Educational Activities. ACS Committee on
Chemical Safety, February 2014; www.acs.org/content/dam/acsorg/
transporting-chemicals.pdf [accessed Apr 2016]
Answers to quiz: 1.e; 2.c;, 3.g; 4.i; 5.d; 6.a; 7.f; 8.b; 9.h
In Case of a Lab Fire
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. Most classroom fire extinguishers should be able to extinguish this kind of fire, but
to make sure, read the label on the fire extinguisher.
• CLASS A: Wood, paper, cloth, trash, and other
• CLASS B: Gasoline, oil, paint, and other flammable
• CLASS C: Wiring, live electrical equipment,
computers, and other electrical sources
• CLASS D: Combustible metals and combustible