1781 Wilcke comes up with the concept of specific heats. Measures the Latent heat of Ice in 1772
1819 Objects have a heat capacity, while materials have a specific heat capacity (often just called specific heat)
was first defined by Pierre-Louis Dulong and Alexis-Thérèse Petit, France, 1819.
The specific heat of a material is the amount of heat required to change a unit mass of a substance by one unit of temperature.
Q is the symbol for heat, ▲Q is the symbol for change in heat.
So in order to raise the objects temperature by a number of degrees this requires so much heat. But these objects are made of different materials, these different materials take different amounts of energy to heat up and cool down. Each different material has a heat capacity specific to the material (and often the temperature range)
All objects have heat as long as their temperature is above 0K.
Everything has a temperature above that, therefore everything has heat.
0K is - 273 oC
Definitions and units.
The heat capacity of an object is defined as the heat energy needed to increase the entire object’s temperature by 1 K.
A calorie (c) is the energy needed to raise the temperature of one gram of water by one celsius degree. This turns out to be a terrible definition as the heat required to raise the temperature of any substance varies with temperature itself. It should be noted that a Calorie (with a capital C) is actually 1000 calories.
- How much energy is required to make a kettle with 1.2 l of water go from 20oC to boiling point ?
- A 100 g cube of aluminum is removed from a bath of boiling water and dropped in a bath of room temperature water (2.00 liters at 20.0 ℃). What is the final temperature of the water and zinc assuming heat loss to the surroundings is negligible? shc Zn = 897 J/kgK
How to do problems concerning Heat Capacity
These are devices that aim to provide warmth around a house during the day time by using night time electricity which is cheaper. They take advantage of a ceramic block that has a specific heating capacity in the order of waters specific heating capacity, but it is more dence (hence smaller) and unlikely to leak heats up at night on the cheaper rate electricity, and radiates this heat out over the course of the day.
Leads to drier houses.
Called heatbanks in Australia
Heat Capacity Experiment 1
to measure specific Heat capacity