The Hot Chocolate Experiment
Learn about insulation the tasty way…
What you will need for this experiment is:
Use a chart to log your recordings during this experiment: You will need a column for the time you measure the temperature, start at 0 minutes, then 2 minutes, 4 minutes, 6 minutes, 8 minutes and 10 minutes; make another column called the temperature – no marshmallows and a third with the temperature – with marshmallows. You can click on the photo of the hot chocolate above to take you to a free chart that you can easily print off.
We first must make this a fair test.
We must only change one thing and in this experiment, and that is marshmallows! Yum! This does mean it is important to make sure both your mugs are identical, both mugs have the same amount of chocolate drinking powder (in our case 25ml in each cup). And when you add the water it is from a freshly boiled kettle each time.
If you have 2 thermometers you can do this experiment simultaneously (at the same time) but we you can also do it separately
What do you think will happen? How will the marshmallows effect the hot chocolate? Will there be a difference between the mug of hot chocolate with the marshmallows and the one without?
Prepare both identical mugs with 25ml of your Chocolate drinking powder.
Boil your water up and as soon as the kettle has finished boiling, pour the hot water into the first cup with the thermometer in the cup and put the kettle aside away from the children.
Wait for the temperature on the thermometer to settle and when it has that is your starting point, ours was around the 90 degree C mark.
Write this down under the 0 minutes time row under the without marshmallows column. This is your starting point
Wait 2 minutes. Check the temperature again and write in under 2 and then wait another 2 minutes and write the temperature after 4 minutes and keep doing this until you've completed 6, 8 and 10.
Now you will need to do the same again but this time, after the just boiled water has been added, you need to put a layer of marshmallows on top.
Again wait until the temperature of the thermometer has settled and this will be your starting point for the hot chocolate with marshmallows test so write this under the with Marshmallows column and the 0 time row. Again every 2 minutes write down the temperature.
The experiment is over. What have you learnt?
Which cooled the quickest?
The mug with marshmallows cooled slower because the marshmallows acted as an insulator stopping the heat from the hot chocolate reaching the air quicker. Heat will always flow from warmer to cooler. There are three ways in which is does this:
Conduction - Which is the way heat moves through materials. It is the way a mug and the thermometer heat up when you add the hot water in this experiment.
Radiation - this travels in a straight line and is the type of heat that comes to earth from the sun. It is also heat that warms your hand when you put it near the mug.
Convection - This is the movement of heat through liquids and gases. Warmer fluids move up and this heats the air at the top of the hot chocolate and because hot air rises it is then replaced by cooler air. what happens when we added the marshmallows is it reduced the air movement over the hot chocolate slowing down the process of convection, the transfer of heat. You would have noticed that there was more steam coming from the hot chocolate without marshmallows than the one with.
Another place you will find insulation:
In houses you will find insulation, it will help a house stay warmer through the colder months and cooler through the heat of summer.
House insulation is made up of foam in a similar way to the marshmallows. This is because they are filled with pockets of air; air doesn't conduct heat very well and the air trapped in the pockets of the foam are trapped, they can’t flow which retains the heat of a house on a cold day or, on a hot day, keeps the heat from outside getting into the house.
Thermos flasks work in a different way. In a thermos flask there are two chambers, it reduces airflow but instead of using pockets of air, it removes air from the equation. You pour your hot chocolate into a thermos flask and it fills a central chamber. There is a vacuum layer between the inside chamber and the outside chamber this means there is no air that the heat can use to transfer the heat from inside the flask to outside of the flask therefore keeping you hot chocolate toasty warm.
So the Vacuum is a more effective barrier. So now the question is how do you like your hot chocolate best? With or without marshmallows?