Heat Capacity: Difference between revisions

Revision as of 22:49, 30 November 2015

Claimed by Adam Schatz

Heat Capacity

The concept of Heat Capacity is integral to understanding how the temperature of a substance rises and falls. Heat Capacity is the ratio of energy added or removed from a substance to the temperature change observed in that substance. Typically, heat capacities are expressed in terms of the amount of heat (kJ, J, or kCal) that needs to be added to raise the temperature of a substance by 1 degree (Celsius, Fahrenheit, Kelvin). Typical units of Heat Capacities are J/g, kJ/kg, and BTU/lb-mass. The SI unit of heat capacity is J/g.

Various Types of Heat Capacities

Specific Heat Capacity

A specific property is an extensive property divided by a specific amount. Therefore, the Specific Heat Capacity of a substance tells you the amount of heat needed to one mass unit of substance one degree. Specific heat capacities are useful for determining the exact amount of heat that must be added to raise some exact amount of substance to some exact temperature. For instance, if you wanted to figure out how much heat was lost from 20 kg of water cooling from 30°C to 25°C, the calculation would involve specific heat capacities.

Molar Heat Capacity

Molar heat capacity is similar to specific heat capacity. It expresses the amount of heat required to raise one gram-mole of a substance by one degree. It is expressed in J/mol-°C. The molar heat capacity of water is 75.37 J/mol-°C.

Heat Capacity at Constant Pressure

Heat Capacity at Constant Volume

First Law

A Mathematical Model

E2 - E1 = Q - W

Applications

Determining Heat Capacities

Examples

Connectedness

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History

Thermodynamics was brought up as a science in the 18th and 19th centuries. However, it was first brought up by Galilei, who introduced the concept of temperature and invented the first thermometer. G. Black first introduced the word 'thermodynamics'. Later, G. Wilke introduced another unit of measurement known as the calorie that measures heat. The idea of thermodynamics was brought up by Nicolas Leonard Sadi Carnot. He is often known as "the father of thermodynamics". It all began with the development of the steam engine during the Industrial Revolution. He devised an ideal cycle of operation. During his observations and experimentations, he had the incorrect notion that heat is conserved, however he was able to lay down theorems that led to the development of thermodynamics. In the 20th century, the science of thermodynamics became a conventional term and a basic division of physics. Thermodynamics dealt with the study of general properties of physical systems under equilibrium and the conditions necessary to obtain equilibrium.

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 ====Specific Heat Capacity====
+A specific property is an extensive property divided by a specific amount. Therefore, the Specific Heat Capacity of a substance tells you the amount of heat needed to one mass unit of substance one degree. Specific heat capacities are useful for determining the exact amount of heat that must be added to raise some exact amount of substance to some exact temperature. For instance, if you wanted to figure out how much heat was lost from 20 kg of water cooling from 30°C to 25°C, the calculation would involve specific heat capacities.
-If A = B and A = C, then B = C
-A = B = C
 ====Molar Heat Capacity====