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the heat
Heat in chemistry and physics is one of the forms of energy that is associated with the movement of particles, atoms, or any particle that enters the composition of matter, and heat is generated through nuclear reactions such as nuclear fusion that occurs in the sun, movement such as friction of machine parts, and electromagnetic radiation, such as that which occurs in Electromagnetic cookers, and chemical reactions such as combustion.
Heat measurement unit
- The Kelvin unit: It is a scale approved in measuring temperature by the Global System (SI), and it is considered a widely used scale in all scientific fields, and it is used if we want to calculate ratios of temperature, and it was named by this name relative to the British engineer and physicist Lord Kelvin.
- Fahrenheit unit F: It is a scale approved only in the United States of America, and it was named after the German physicist Daniel Gabriel Fahrenheit.
- The Celsius unit is a major scale adopted in daily life in most countries of the world, and it was named after the Swedish astronomer Anders Celsius who suggested that the zero degree be identical to the degree of water freezing, and that its boiling point corresponds to a hundred in 1747 AD, and it is used in The field of weather forecasts.
Transfer between temperatures
Converting from Kelvin to Celsius or vice versa:
The relationship between them is considered constant, so it is sufficient to add a certain fixed number to the degree in order to obtain the kelvin, and subtract the same fixed number from the kelvin to obtain the percentage degree, and that number is 273, which is as follows:
- Kelvin = Celsius degree +273.
- Percentage = Kelvin -273.
Converting from Fahrenheit to Celsius or vice versa:
Converting from Fahrenheit to Celsius is more difficult than Kelvin; As it depends on the process of subtraction and division into mixed numbers, so there is a need for a calculator as follows:
- Celsius degree = (Fahrenheit -32) ÷ 1.8.
- Fahrenheit = (percentile x 1.8) +32.
Heat transfer methods
- Conduction: Energy is transferred by contact in good conductors quickly, and this occurs mainly through the exchange of free movement of electrons as well as the collision of particles or atoms with each other and the exchange of vibration of the atoms.
- Radiation: Heat moves in a vacuum without the medium having any role, such as the spread of sunlight and its arrival to the ground.
- Pregnancy: It is the way heat is transferred in gases and liquids. Where if a liquid or a gas is heated, it expands, rises up, and its density decreases. The colder liquid or gas also decreases to occupy its place, and from this step the load current is created.
| Concept | the definition |
|---|---|
| Fahrenheit Ladder | It is rarely used for scientific purposes, and it is an ancient English system in which it is given a degree of 32 ° F for ice, and 212 ° for evaporation |
| Celestial ladder | Also known as the Celsius scale of temperature, it is a standard scale of temperatures in degrees Celsius, and its graduation is similar to the scale of the absolute temperature, but it gives zero to the freezing point, and 100 ° C for evaporation |
| The absolute temperature scale | It is used in the study of thermodynamics or thermology, and it is a standard temperature scale that uses the kelvin unit |
| Fixed point | It is a temperature at which noticeable changes occur under specific conditions, and a value for which all other temperatures can be measured |
