Dec. 12-16

Q/m=amount of energy per
unit of mass

This week, I reviewed over energy. In between particles, attractions and chemical bonds involve electrostatic interactions. This is what holds the particles together. Like magnets sticking onto the refrigerator because the magnetic poles attract to the metal on the refrigerator, particles work the same way.

I also realized that the attraction between particles depends on the physical changes of a substances. These states of water are very different not only because of their physical states but because of the attraction of their particles. Solid has stronger attraction between particles because the particles in a solid have the least amount of energy so the particles are closer together--like relatives who live a few blocks in contrast to miles away. The lesser the distance, the greater the contact and the visits. That is what happens in a solid. The particles have strong attractions and move the least because there isn't enough energy to change the arrangement of particles.

LOL diagram of water evaporating

However, in a gas, the particles are the farthest apart. In this case, the relatives live miles away from you, which means less contact during the year. In a gas, the particles barely bump into each because they are farthest apart. The particles in a gas, thus, have the most amount of energy because it takes a higher amount of energy to separate the particles and make them move faster.

When physical states of substances change, this is because the attractions between the particles must be overcome in a solid to change to a liquid or gas. But, let's keep this in mind. Just because the arrangement of particles changes, it doesn't mean that the motion of particles has changed. They could still move at the same rate. For example, a dozen cars drives straight to the store each at 25 miles per hour. But, when six cars change direction and drive to the mall at the same speed, it only changes the arrangement of traffic.

Heat of Fusion and Heat
of Vaporization

This is what occurred when water at a temperature of 100ºC was not boiling. Even though the arrangement of particles became less structured, not enough energy, though, could cause the substance to change state. As a result, the liquid still remained a liquid with different arrangement of particles.

The same goes without saying for the motion of particles. Just because it changes, it doesn't mean that the arrangement of particles has. The cars on the highway could still be going the same destination and if they accelerated from 65 miles per hour to 70 miles per hour, the cars would still be in the same order. So, in particles, if the motion of particles has changed and not the motion, then this means that they had enough energy to make them move faster but not enough energy for the substance to change state. Thus, particle attraction was not completely overcome since not enough energy was in the th account.

State changes in Heat of Fusion and
Heat of Vaporization and
particle motion

For instance, this is what happened when the water on the T-shirt evaporated. The state of the water changed from liquid to gas, but the temperature of the water couldn't have change because if it were at the boiling point (100ºC), it would be scalding! So, what then caused the water to evaporate? Energy did. Enough energy in the ph account was used to change the motion of the particles and accelerate them. However, there was not enough energy to change the arrangement of particles. Thus, the preconceived notion that water had to evaporate at 100ºC is not entirely accurate.

Therefore, a solid has the most orderly arrangement of particles and the lowest amount of energy as well as motion of particles. The liquid has the second most fluid arrangement of particles, meaning they move freely about but not as rapidly as gas particles. Thus, liquid is more structured than a gas and has less energy. Gas has the most amount of energy with the particles being the farthest apart with the least attraction. Thus, the distance between the particles and the attraction between them has an inverse relationship much like volume and density.

This week, I learned about Heat of Vaporization and Heat of Fusion. Heat of Vaporization (enthalphy of vaporization) is the amount of energy that is required to convert a unit mass of a liquid into the vapor without a change in temperature. Heat of Vaporization occurs in state changes of liquid to gas and vice versa: (Vaporization) or (Condensation). Heat of Fusion (enthalphy of fushion) is the amount of energy that is required to convert a unit mass of a solid into the liquid without a change in temperature. Heat of Fusion occurs in state changes of solid to liquid and vice versa: (Melting) or (Freezing).