Heat Capacity
There
are three different types of heat capacity, and they are all loosely
referred to as “heat capacity” ... and that confuses students.
“Heat capacity” (C) is the amount of heat required to heat a particular object (like a rod of iron) by 1ºC. Bigger object → larger heat capacity. The units of heat capacity are J/ºC.
“Specific heat capacity” (Cp) is the amount of heat required to heat 1 g of a particular substance by 1ºC. Bigger object → no change in specific heat capacity, since specific heat capacity is for only 1 g of the substance, not the whole lot of it. The units of specific heat capacity are J/g/ºC.
RARE: “Molar heat capacity” (Cm) is the amount of heat required to heat 1 mol of a particular substance by 1ºC. Bigger object → no change in specific heat capacity, since specific heat capacity is for only 1 mol of the substance, not the whole lot of it. The units of specific heat capacity are J/mol/ºC.
It is more common for questions to involve specific heat capacity that the other two, but you should be ready to use any of the three. Often the units of the given heat capacity will tell you which one you're dealing with.
Heat capacities allow scientists to predict how much the temperature of a substance will rise/fall given a certain heat change. The most important application of this is calorimetry.
“Heat capacity” (C) is the amount of heat required to heat a particular object (like a rod of iron) by 1ºC. Bigger object → larger heat capacity. The units of heat capacity are J/ºC.
“Specific heat capacity” (Cp) is the amount of heat required to heat 1 g of a particular substance by 1ºC. Bigger object → no change in specific heat capacity, since specific heat capacity is for only 1 g of the substance, not the whole lot of it. The units of specific heat capacity are J/g/ºC.
RARE: “Molar heat capacity” (Cm) is the amount of heat required to heat 1 mol of a particular substance by 1ºC. Bigger object → no change in specific heat capacity, since specific heat capacity is for only 1 mol of the substance, not the whole lot of it. The units of specific heat capacity are J/mol/ºC.
It is more common for questions to involve specific heat capacity that the other two, but you should be ready to use any of the three. Often the units of the given heat capacity will tell you which one you're dealing with.
Heat capacities allow scientists to predict how much the temperature of a substance will rise/fall given a certain heat change. The most important application of this is calorimetry.
