If you can’t stand the heat, then stay out of the kitchen! Heat plays an important in our lives, not just idioms. Indeed, our universe is made up of energy and matter. What is matter? Matter is made of atoms and molecules. Energy then causes these atoms and molecules to stay in motion. Together, this motion creates a form of energy called heat.
Here are seven facts and characteristics of heat you need to know:
1. Types of Heat
In order to understand the characteristics of heat, it is important to know what ‘heat’ means. Heat is the transfer of kinetic energy from one object or medium to another source or object. The transfer of heat energy can occur via three methods: convection, conduction, and radiation.
2. Heat Conduction
Heat transfer via conduction takes place when two objects are in direct contact and the temperature of one object is greater than the temperature of the other object. The heat transfer is usually via kinetic energy from the warmer object to the cooler object. A classic example of heat conduction is taking a warm shower on a cold day. The warm water will quickly warm up the cold body.
3 Heat Transfer
Heat transfer by convection occurs when there is motion of the gas or liquid particles that transfer energy from a hotter area to a cooler area. A classic example is the use of a heater during a cold day. The warm air generated by the heater rises to the top and the cold air falls to the bottom; eventually, there is equalization of the temperature and the entire home feels warm.
An example of heat transfer by radiation is the fireplace, which transfers energy within a room via the heated air molecules. Another classic example of radiation heat transfer is the heat from the sun which warms the earth.
4. Heat Measurement
In order to determine the amount of heat transferred in any process, we define it as the total amount of transferred energy minus any macroscopic work and any energy contained in the matter that is transferred.
Heat should occur by a path that does not include any transfer of matter. Certain materials have the characteristics of resisting heat, which will lower the amount of heat during the transfer. The SI unit of heat is joule (J) and the symbol used to represent the amount of heat that is transferred in a thermodynamic process is Q. Heat is measured by its effect on the state of interacting bodies.
For example, you can measure heat when the ice melts or when there is a change in temperature. The process of quantifying heat via temperature change is calorimetry.
5. Heat Temperature
The calorie is the International System of Units that quantifies the energy transfer. This is the amount of heat necessary to increase the temperature of one gram of pure water by one degree Celsius. Sometimes the kilocalorie is used to quantify a unit of heat. In older texts, the British thermal unit is also used for the same purpose. The British version uses Fahrenheit instead of degrees Celsius.
6. Heat Expansion
Heat causes expansion: when liquids, solids, and gases are heated, they will expand; and when they cool down, they will get smaller or contract.
The reason liquids and gases expand is because the molecules are moving rapidly when heated and this also allows them to move further apart so that they take up more space. When the liquid or gas is heated in a closed container, the molecules will hit the walls, and this raises the pressure. The higher the number of molecular collisions with the wall of the container, the higher the pressure.
A real-life example of this is when a fire causes an explosion in a home. The heat inside the home causes the excited molecules to move at fast speeds around the room, pushing against the windows, walls, and ceiling. Since windows are usually the weakest segment of the home, they break and release the pressure.
7. Heat vs. Temperature
It is important to understand that heat and temperature are not the same thing. Temperature only reveals how hot or cold an object is. While they both may be related to each other, they are not the same concept.
Heat refers to the total energy of molecular motion in a particular substance. Temperature, on the other hand, is a measure of the average energy of that substance. Heat energy depends on the speed, number, and type of particles in an object, but temperature does not depend on any of these variables.
A perfect example of this concept is a cup of water versus a large tub of water. The temperature of the water may be the same in both these objects, but the tub of water will have more heat because it has more water and more thermal energy overall. Temperature is measured on the Fahrenheit (F) or Centigrade (C) scale. For example, water freezes at 32 degrees F or 0 degrees centigrade. On the other hand, water boils at 212 degrees F and 100 degrees centigrade.
