Nicholas Academy

Custom Search

Science | Science Experiment of the Week 11 | 314 - Hottest Part of a Flame

Which color flame is hottest - red, yellow or blue? It is a great question, and the answer may fool you.

This Week's Experiment - #314 Hottest Part of a Flame

(note: I received an email informing me that Mr. Krampf has the wrong temperature conversions in this experiment. I don't have permission to alter these experiments, so please be advised that the Fahrenheit to Celsius conversions are incorrect. Thank you to David Knox for pointing out the mistake.)

These experiments are from Robert Krampf - The Happy Scientist

This week's experiment comes from a question that I got during an energy show. A student asked what color flame was the hottest. It is a great question, and the answer may fool you. To investigate this, you will need:

a candle
wooden toothpicks or matchsticks
a metal spoon
a bowl of water

First a warning. We will be using the candle flame to burn the toothpicks. Be sure you have an adult with you and use common sense. Don't burn plastics as some of them produce toxic fumes when they burn.

Light the candle and look carefully at the flame. At the bottom, you will see an area of blue flame. Above that is the yellow part of the flame. If you look carefully, you will see a darker area in the center. If you look very closely (be careful not to burn your nose) you may also see a very thin layer of blue flame over the entire surface of the flame.

Now, which part of this flame is the hottest? Lets see if we can use a wooden toothpick to find out. Hold one toothpick and put the end of it into the blue area at the base of the flame. Notice how long it takes for it to catch fire. Quickly put the burnt toothpick into the bowl of water. Try the same thing in the flame just at the top of the wick. Did it catch fire quicker? Yes. OK, now lets move upwards to the top of the dark area inside the flame. Last, try holding a toothpick at the very top of the flame. Which toothpick caught fire quickest? The top one, right? So that is the hottest part of the flame, right? NO!

This is an example of how experiments can be misleading. Actually, the hottest part of the candle flame is the blue part, at 1670 degrees F (1400 C.) That is where the flame has the most oxygen and you are getting complete combustion. The reddish part is the coolest part, about 1070 F (800C).

Wait a minute. If the top is not the hottest part, why did the toothpick burn the fastest there? To get an idea of the answer, turn on the hot water in your sink. Hold a metal spoon in the stream of hot water for about 15 seconds. By that time, the spoon should have heated up to the same temperature as the water. Remove the spoon from the water and touch it with your finger. Notice how hot it feels. Then carefully put your finger into the stream of hot water. Does it feel hotter than the spoon? Yes! If they are the same temperature, why does the water feel hotter? Heat energy is moving from the spoon to your finger. The spoon is heating your finger, but your finger is cooling the spoon.

With the stream of hot water, heat moves from the water to your finger, but then that water flows past and your finger is now touching more water, which still has all its heat energy. You have a constant stream of fresh, hot water transferring heat to your finger, so your skin heats up faster than it did with the spoon. The same thing happens in the candle flame. The heated gases of the flame are rising. Holding the toothpick at the top of the flame means that it has a constant stream of freshly heated gases flowing past it, so the toothpick heats faster and it bursts into flame. At the bottom of the flame, it is more like the spoon. The toothpick cools the flame as the flame heats the toothpick, so it takes longer before the wood is set on fire.

Once again, be safe and be careful. Have a fun filled week.

Science Experiments:
211 - 220 | 221 - 230 | 231 - 240 | 241 - 250 | 251 - 260 | 261 - 270
271 - 280 | 281 - 290 | 291 - 300 | 301 - 310 | 311 - 320 | 321 - 330 | 331 - 340

Education Posters at | Clearance Posters

Nicholas Academy Index


Roman numerals, multiplication, state and world capitals, order of presidents, chemical elements, parts of speech, Spanish numbers, plus more.


Explore animation, filmmaking, build online cities, create works of art, write stories, create your own web site.


Math quizzes, printable charts and flashcards, math tools. Multiplication, roman numerals, fractions, addition, more.


Science games and quizzes, posters, science experiments.

Social Studies

Posters, printables, the Lifeboat Game, college essays, fifty states resources, educational quizzes for presidents, capitals, flags.


Test your knowledge with these fast, fun, and educational quizzes. Roman numeral addition, world capitals, presidents in order, the elements, world flags, and more.

Educational Posters

Parts of speech, civil rights, medieval, periodic table of elements, music, astronomy, world maps with flags, literature, poetry, biology.

Science Experiments

Science can be fun and understandable. Free Experiment of the Week, featuring experiments that are unusual, safe, dramatic, cheap, and fun. From Robert Kramp's Science Education Co.

Middle Age & Renaissance

Artists, wars, armour, castle games, recipes, geography, quizzes, fashions, pictures of weapons, music, old world maps, women of medieval times, medicine, language, and more.

Useful Tools

Reading systems, loan programs, flashcard, worksheet and test makers, game creators, board games, percentage calculator, puzzle creator, timeline template.

Language Arts

Alphabet flash cards, English and Literature and Lord of the Rings posters, printable parts of speech chart.


Fun learning activities, games, lessons and quizzes. Eartraining software, music theory and history, music posters, guitar posters.


Free online courses, including grade school and accredited high school, online public schools, computer internet course, foundational phonics, more.

Foreign Language

Spanish and Korean resources - printable flash cards for numbers and the alphabet, Korean keyboard chart.

Storage - Alextown

Temporary home to Alextown - a site created for my son. Maille armor pictures, ninja pictures, more.

If you have comments, questions, or would like to report a broken link,
please send an email to Cheryl at

© 2000-2015 Nicholas Academy
Nicholas Academy Site Map
privacy policy