Experiment Of The Week The Science of Pizza

If you have ever eaten pizza, you have probably burned your mouth on the cheese.  If the crust of the pizza is cool enough for you to hold, why is the cheese still hot enough to burn you?  To find out, you will need:

a nice, hot pizza

Cut yourself a nice, hot slice of pizza, but do not take a bite.  Instead, touch the crust.  It will be very warm, but it should not be hot enough to burn you.  Do not touch the sauce or the cheese, because they will be hot enough to cause a burn.  Why?

It has to do with a property known as specific heat.  That is the amount of heat energy that a substance has to absorb to raise its temperature.  Some substances, like the crust of the pizza, have a low specific heat.  They do not have to absorb much heat energy to raise their temperature.  That means that they do not have to lose much heat energy to cool off.  The pizza crust was able to transfer enough heat to your fingers to cool it, without transferring enough to burn your fingers.

On the other hand, the sauce and cheese have a high specific heat.  It takes quite a bit of heat energy to warm them up.  If you tested the temperature while the pizza was cooking, you would find out that in a 450 degree oven, the crust quickly reaches 450 degrees, while the sauce and cheese take much longer.  Since they have to absorb a lot of heat to get to that temperature, they have to get rid of the same amount of heat energy to cool down.  If you touch the sauce too soon, quite a bit of that heat energy is transferred to your skin, giving you a burn.

So the next time you have pizza, let it cool a bit before you take your first bite.  

Have a wonder-filled week.