Taste the Explosion
Explosions tend to attract everyone’s attention. Whether it’s the next big action movie, or a pop bottle full of mentos everyone loves the excitement it brings. Can you taste an explosion though? Yes! Thanks to pop rocks!
What makes them explode in your mouth? To understand how it works first we need to look at Kinetic Molecular Theory (KMT). There are three things that you can physically observe about the KMT. First is the temperature. Temperature affects how fast molecules move. If it is hot the molecules are going to move faster versus if it’s cold then molecules are going to move slower. The next thing is pressure. Pressure is the amount of times a molecule hits the side of a container and how hard it hits. There are two types of pressure, internal and external pressure. Internal pressure is the pressure that takes place inside the container while external pressure is the pressure that is exerted on the outside of the container. When the molecules hit faster and harder the pressure increases. Lastly we can look at volume. Volume is the amount of room something has. If there is a lot of volume there won’t be much pressure.
In addition to those three things the KMT is typically broken down into five major parts. The first part is the idea that the volume of particles appear to take up zero space, but in reality they are so small that the amount of volume the particles occupy is almost nothing. The second part is that particles are in constant motion. They can move in three different ways. Solids have particles that move vibrational, liquids have particles that move rotational, and gases have particles that move translational. The third part is that particles lose no energy when they collide. This is because their collisions are elastic. The idea of elastic collisions is that even though the particles are moving around colliding into things they don’t behave like normal objects would and slow down when they hit other materials, but rather they keep the same amount of momentum.The fourth part is that particles are not attracted to each other. The last part is that the kinetic energy of a particle is related to the temperature. The hotter the temperature is the higher the kinetic energy is. Versus the colder the temperature is the lower the kinetic energy is.
Okay now back to Pop Rocks! How are these two things connected?
This is a close up image of a couple of pop rocks. The pop rocks can be compared to an inflexible container for the CO2 particles. The internal pressure of the rocks or is higher than that of the external pressure. When the rocks are exposed to the water the walls containing the CO2 are weakened and the CO2 particles crack the walls and the internal and external pressures equalize creating the pop sound!
Watch this clip of a pop rock doing its thing!
Pop Rocks may not be the typical type of large-scale eruption that comes to mind when we think of explosions, but it’s one with a delicious burst of flavor that explains Kinetic Molecular Theory.