Heat and temperature

The two terms, heat and temperature often considered synonymous, refer to two key notions that should not be completely confused. When we talk about heat and temperature in everyday language, we don’t always use them correctly and we often get confused. There is a substantial difference between them and therefore we tried to explain it in the best possible way to clarify the ideas.

Although two entities are closely related to each other, heat and temperature represent two different physical quantities, used in discussions of the structure of matter and all thermal phenomena. The fundamental distinction to be made is the following: temperature is a property of the body, heat is energy in transfer.

What is it :

It is an energy in transit that flows from higher to lower temperature It is a sensation of heat and causes moving or kinetic energy
What it is measured with : It is measured with the calorimeter It is measured with the thermometer. Unit Calories, Joules or Kilocalories Units Celsius, Kelvin, Fahrenheit.

The concepts of heat and temperature are studied together in science, because they are somewhat related, but not in the same way. The terms are very common, due to their wide use in our daily lives. There is a thin line that delimits heat from temperature, in the sense that heat is considered a form of energy, but temperature is a measure of energy.

The fundamental difference between heat and temperature is slight but significant, heat is the general energy of molecular motion, while temperature is the average energy of molecular motion.

Temperature defines the state of thermal excitation of a body. As is easy to understand, by thermal agitation we mean the movement, called agitation, of the many atoms that make up each body. These movements are rotary, translational and vibratory and their sum generates an energy called thermal. Temperature quantifies this energy that is detected by using a specific instrument called a thermometer, whose scientific unit of measurement is the degree of Kelvin. In summary, temperature is a property of matter measurable through the thermometer, in the same way that length is a property that is measured with the meter.

What is heat:

Heat is a form of thermal energy, which is transferred between two bodies at different temperatures. Heat is therefore a “moving” energy, which is a transit energy.

Heat characteristics

* A higher temperature body can transfer heat to bodies with lower temperatures, but the reverse process cannot occur. Heat is nothing more than a form of thermal energy that is transferred between two bodies that are at different temperatures: so Therefore, it is “transferred”. Also, think that a higher temperature body transfers heat to a lower temperature body, but the opposite cannot happen!
* How is heat measured? Heat is measured in Joules (J), although in chemistry we often turn to calories (cal), which is the amount of heat needed to raise the temperature of a gram of distilled water from 14.5 ° C to 15.5 ° C, at the 1 ambient pressure.
* Heat is measured with an instrument called a calorimeter.

Heat example

To understand precisely what the term heat means , a practical example might be helpful. When placing cold hands under a stream of hot running water, the pleasant sensation of heat that is felt is caused by the thermal energy contained in the water molecules at a higher temperature that comes into contact with the surface at a lower temperature. of the hands.

What is temperature:

The temperature , on the other hand, is a property indicating the thermal state of a body, ie, the state of agitation of the molecules which form the body. Temperature measures the thermal state of a body, which would be the state of agitation of the molecules that compose it.

Temperature characteristics

* In fact, when heat is transferred to a body, the molecules that compose it begin to move faster and faster: this phenomenon gives rise to kinetic energy (the energy of movement).
* How is the temperature measured? Temperature is, therefore, the measure of the average kinetic energy of the particles that make up a body. The unit of measurement for temperature in the International System is degrees Kelvin (K), which refers to the temperature scale absolute, but in everyday life (for example, to measure the temperature of the external environment) the degree Celsius (° C) is used much more, referred to the scale Celsius or centigrade or degrees Fahrenheit.
* The temperature is measured with the thermometer.

Temperature example

We can see a very simple example, when we heat water as it heats up we see an upward movement, that is the energy in movement.

conclusion

The energy exchange will take place until the two bodies come into contact and reach the same temperature. In other words, the energy transfer and the intensification of the molecular motion of the colder mass will continue until there is a balance of thermal energy between the materials involved in the propagation.

In conclusion, it should be clear that the term heat refers to energy in transit , while temperature is a physical quantity that defines the degree of thermal agitation of the particles that make up each substance and that are in incessant motion.

Both heat and temperature are the concepts of thermodynamics ; which works together to make energy flow from the warmer body to the cooler body. While heat depends on the number of particles in an object, temperature does not depend on a number of particles in an object because it is an average measurement.