Sensible heat . Amount of heat that a body absorbs or releases without changes in its physical state (phase change). When sensitive heat is supplied to a body, the temperature increases .
Summary
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- 1 Heat
- 1 Supply sensible heat
- 2 Conditions so that no variations occur
- 3 External link
- 4 Sources
Hot
Heat supply to water
Heat (Q) refers to energy in transit that flows from one part of a system to another or from one system to another, by virtue of only a difference in temperature.
In physics we find various types of heats for a better understanding and understanding of the different processes and phenomena that occur in substances and bodies, thus we can define sensible heat, latent heat and specific heat .
Sensible heat is that which a body or substance is capable of absorbing or yielding without changes in its molecular structure, that is, in its physical state.
The heat absorbed or transferred depends on the pressure that is exerted on it, taking as a reference the temperature of 0o C. The higher the pressure , the higher the sensible heat and the lower the pressure, the lower the sensible heat.
Supply sensible heat
disorderly movement of particles in a substance as its temperature increases due to the supply of heat
When a substance with a temperature below its boiling point is heated, it absorbs heat and increases its temperature ( sensible heat ), until reaching the boiling point corresponding to the pressure to which it is subjected, after reaching this point, the ascent stops. temperature and any additional amount of heat supplied to it will no longer increase the temperature.
Example: when water is heated to atmospheric pressure , it absorbs sensible heat and its temperature rises progressively, until it begins to boil, stabilizing at 100 ° C.
If the heating occurs at a pressure lower than atmospheric pressure, then the water will begin to boil at a temperature below 100o C, since the boiling point decreases, requiring less sensible heat to reach this point from which the supplied heat will receive the name of heat latent.
The amount of heat necessary to heat or cool a body is directly proportional to the body’s mass, the pressure it is subjected to, and the difference in temperature between the hot and cold focus.
Conditions so that no variations occur
For this, it is essential to establish conditions so that variations do not occur in the points of change of state of the substances, therefore:
At constant pressure
- Qs = ΔH = mCp (t2 – t1)
Where:
- H is the enthalpy of the system,
- m is the mass of the body,
- Cp is the specific heat at constant pressure (defined as the amount of heat required to increase the temperature of the unit of mass of a body at constant pressure by one degree),
- t2 is the final temperature,
- t1 is the initial body temperature.
At constant volume Qs = ΔU = mCv (t2 – t1) Where:
- Cv is the specific heat at constant volume,
- U represents the internal energy of the system.
Specific heat values vary with the substance, the ambient temperature and the state of aggregation, example:
| Substance | Specific heat | Meaning |
| Water | 1 cal / g or C | To raise the temperature of 1 g of water by 1 degree centigrade, 1 calorie is required. |
| Aluminum | 0.217 cal / g or C | To raise the temperature of 1 g of aluminum by 1 degree centigrade requires 0.217 calories. |
