Definition of the word heat capacity

The concept of heat capacity can be traced back to the observations of 18th century French scientist, Rene Antoine Ferchault de Réaumur. He discovered that different substances expand at different rates when heated, and this led him to hypothesize that they also absorbed varying amounts of heat to increase their temperature by a given amount. The term "heat capacity" was first introduced by British physicist, Lord Kelvin, in the late 19th century. He defined it as the amount of heat required to raise the temperature of a substance by one degree Celsius, and expressed it in units of calories (now expressed in joules) per gram per degree Celsius (now degree Kelvin or degree Celsius). In simpler terms, heat capacity refers to the ability of a substance to absorb and retain heat without undergoing a change in temperature. It depends on several factors, such as the arrangement of molecules in a substance and their ability to vibrate and collide with each other. In summary, the word "heat capacity" reflects the idea that certain substances have higher or lower abilities to hold onto heat energy, which in turn affects their behavior and responses to changes in temperature.