Heat
Heat Heat is a way of transferring energy between a system and its surroundings that often, but not always, changes the temperature of the system. Heat is not conserved, it can be either created or destroyed. In the metric system, heat is measured in units of calories, which are defined as the amount of heat required to raise the temperature of one gram of water from 14.5oC to 15.5oC. In the SI system, the unit of heat is the joule.
Heat Capacity The heat capacity of a substance is the amount of heat required to raise the temperature of a defined amount of pure substances by one degree (Celsius or Kelvin). The calorie was defined so that the heat capacity of water was equal to one. 
Specific Heat The specific heat of a substance is the number of calories needed to raise the temperature of one gram by 1oC. Because one degree on the Celsius scale is equal to one Kelvin, specific heats in the metric system can be reported in units of either cal/g-oC or cal/g-K. The units of specific heat in the SI system are J/g-K. Because there are 4.184 joules in a calorie, the specific heat of water is 4.184 J/g-K. The ease with which a substance gains or loses heat can also be described in terms of its molar heat capacity, which is the heat required to raise the temperature of one mole of the substance by either 1oC or 1 K. In the metric system, the units of molar heat capacities are therefore either cal/mol-oC or cal/mol-K. In the SI system the units of molar heat capacities are J/mol-K.
Latent Heat When ice is heated, the heat that initially enters the system is used to melt the ice. As the ice melts the temperature remains constant at 0oC. The amount of heat required to melt the icehas historically been called the latent heat of fusion. Once the ice has melted, the temperature of the water slowly increases from 0oC to 100oC. But once the water starts to boil, the heat that enters the sample is used to convert the liquid into a gas and the temperature of the sample remains constant until the liquid evaporates. The amount of heat required to boil, or vaporize, the liquid has historically been called the latent heat of vaporization.
More than 200 years ago, Joseph Black distinguished between sensible heat and latent heat. Heat that raises the temperature of the system can be sensed, but heat that results in a change in the state of the system from solid to liquid or from liquid to gas is latent. Like the latent image on photograph film that hasn't been developed or latent fingerprints that can't be seen with the naked eye, latent heat is heat that enters the system without changing the temperature of the system.
Heat and The Kinetic Molecular Theory The system is the small portion of the universe in which we are interested, such as the water in a beaker or a gas trapped in a piston and cylinder, as shown in the figures below. The surroundings are everything elsein other words, the rest of the universe.
The system and its surroundings are separated by a boundary. Heat is transferred across the boundary between a system and its surroundings. One of the fundamental principles of the kinetic theory is the assumption that the average kinetic energy of a collection of gas particles depends on the temperature of the gas and nothing else. A gas becomes warmer if and only if the average kinetic energy of the gas particles increases. Heat, when it raises the temperature of a system, produces an increase in the speed with which the particles of the system move, as shown in the figure below.
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit of mass. The specific heat capacity of a material is a physical property. It is also an example of an extensive property since its value is proportional to the size of the system being examined.
In SI units, specific heat capacity (symbol: c) is the amount of heat in joules required to raise 1 gram of a substance 1 Kelvin. It may also be expressed as J/kg·K. Specific heat capacity may be reported in the units of calories per gram degree Celsius, too. Related values are molar heat capacity, expressed in J/mol·K, and volumetric heat capacity, given in J/m3·K. Heat capacity is defined as the ratio of the amount of energy transferred to a material and the change in temperature that is produced: C = Q / ΔT where C is heat capacity, Q is energy (usually expressed in joules), and ΔT is the change in temperature (usually in degrees Celsius or in Kelvin). Alternatively, the equation may be written: Q = CmΔT Specific heat and heat capacity are related by mass: C = m * S Where C is heat capacity, m is mass of a material, and S is specific heat. Note that since specific heat is per unit mass, its value does not change, no matter the size of the sample. So, the specific heat of a gallon of water is the same as the specific heat of a drop of water. It's important to note the relationship between added heat, specific heat, mass, and temperature change does not apply during a phase change. The reason for this is because heat that is added or removed in a phase change does not alter the temperature. Also Known As: specific heat, mass specific heat, thermal capacity Water has a specific heat capacity of 4.18 J (or 1 calorie/gram °C). This is a much higher value than that of most other substances, which makes water exceptionally good at regulating temperature. In contrast, copper has a specific heat capacity of 0.39 J. This chart of specific heat and heat capacity values should help you get a better sense of the types of materials that readily conduct heat versus those which do not. As you might expect, metals have relatively low specific heats.
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What term is defined as the amount of heat that is required to raise the temperature of one gram of a substance by one degree Celsius?
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