The Real Life Chemistry
of Marshmallows


Chemistry classes teach abstract ideas about atoms and molecules. These ideas are often difficult to apply to everyday life. It can be hard to see how what you learn in Chemistry is in any way relevant to your life. The fact is that Chemistry is all around you and understanding it can enrich your daily experience immensely. From food and cooking, to cleaning, to the clothes you wear and the medicines you use to keep you healthy. Chemistry is involved in literally every part of your life.

For this at-home experiment you will make home-made marshmallows. You will learn about how adding sugar makes the boiling point of water rise and how proteins can be shaped into sub-microscopic networks which can trap air bubbles. Do this with some friends and make some hot cocoa on these cold winter days! You will follow a recipe that I have put together based on several recipes I have read. I have made it myself and it is delicious. The recipe is below.

Read the background information available at this link before you begin making the recipe. It will help you to understand the science behind what you are doing. Also, it will be an important resource for answering the questions required for this assignment. Do not do the project described on that page.
also here:


Cooking on a hot stove can be a hazard, especially if young children are involved. Sugar solutions become much hotter than boiling water and should be handled with great care.

The stand mixer will be used at high speed. Keeps hands away from moving parts.

Things You Will Need

You will absolutely need to use a stand mixer, not a hand mixer, for this recipe. If you do not have one I strongly recommend working with a classmate who has access to one. Failing that, a hand mixer may be made to work but only if you take care to use it for a shorter period of time and guard against overheating.

You will need a candy thermometer or an instant-read digital thermometer, as used for cooking meats. It must read to temperatures up to at least 250°F. The thermometer does not have to stay in the pot while you cook. In case you don’t have a candy thermometer, this web page will be useful. From the Exploratorium science museum in San Francisco: The Cold Water Candy Test:

For a list of ingredients, see the left-most column of the recipe table below.


(yields about 40 large marshmallows)
Grease 9x13-in. pan with butter or cooking spray and powder with powdered sugar
3 envelopes (21 g) unflavored gelatin
a common brand is Knox
Soak ~10 min. in the mixing bowl of the stand mixer Once the syrup mixture has reached 250°F, add it slowly to the stand mixer bowl while stirring at low speed with the whisk attachment Add the salt, then mix until it has fluffed up,
about 10 - 12 min.
Stop the mixer. Add the vanilla extract and mix slowly for about 30 sec. Use a spatula coated in powdered sugar to put the marshmallow mixture into the pan. Allow to cool in pan for 3 hrs. Turn marshmallow slab out onto a cutting board sprinkled with powdered sugar. Use a pizza wheel to slice into pieces. Add additional powdered sugar to keep from sticking.
½ cup (120 mL) water
1½ cups (350 g) sugar Combine sugar, corn syrup, and water and
boil until the temperature reaches 250°F (121°C); then remove immediately from the heat
1 cup (240 mL) corn syrup
¼ cup (60 mL) water
¼ tsp. (1.5 g) salt
1 Tbs. (15 mL) vanilla flavoring
Powdered sugar

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Clean equipment immediately after using because the sugar syrup can harden and become like glass glued to the surface of your pots and bowls. Cleaning up the sugar syrup is easy if you do it right away and use plenty of very warm water. Soaking a pan in hot water for a few minutes before scrubbing it greatly reduces the effort needed to get it clean.

The Report

Type a one-page paper which answers the following questions in a numbered-response format. Write no more than one solid paragraph in response to each one. You will be graded based on how clearly you demonstrated significant care in carrying out the experiment and how deeply you have thought about what it means.

  1. Read the article you will find at this link: Define boiling point elevation and explain how it works.
  2. Normally, when a liquid boils it does so at a constant temperature. This was not the case for this mixture. Heating the syrup mixture drives off water vapor and makes the sugar more concentrated. How did the temperature change as you heated the syrup mixture in the pan? Most importantly, why did the temperature change?
  3. Why was it so important to measure the temperature of the sugar syrup mixture as you cooked it? Explain using the science concepts from the article referenced in the first question and from this article: The Cold Water Candy Test: or here:
  4. Sugar crystals in marshmallows would make them crunchy, and this would be a defect. Read about crystallization and candy at this article: or here: How does using corn syrup prevent the formation of sugar crystals?
  5. What is the purpose of the gelatin in this recipe? How did the threads of protein in the gelatin create the conditions necessary for a fluffy marshmallow? Consider the need to retain many tiny air bubbles and the effect of whipping on proteins. Read about food foams here: or here:
  6. Add one or more photos of your work .
  7. Add an original illustration (not an image found on the internet) of what is happening at the molecular level which explains why the boiling point of a solution is higher than the boiling point of water alone. Do some research and use your imagination: the point of making an illustration is to demonstrate that you understand a concept. Cartoonish drawings are acceptable--try to do them in the style of the Modeling the Molecular Level activity.
  8. If you had any difficulties in getting the recipe to work, please describe them here along with your solution to the problem.
  9. What made this experiment fun? Of if you didn’t enjoy it, why not?
Sources consulted that were not already linked in the main document:
Cooking for Engineers marshmallow recipe:
Alton Brown’s recipe:
Last updated: Feb 08, 2021       Home