1. Lecture #1 Heat of a System
ThermoChemistry
Lecture #1
Heat of a System

2. What is Heat?
It is a form of energy that can be converted to other forms of energy.
As energy, it can be defined as the capacity to do work.
From Physics, it is measured in units of Joules

3. Why do we care about Heat?
Because many physical changes and all chemical changes involve the movement of heat either in or out of a defined system.

4. Calculation of Heat Content
This one is quite simple.
The equation that will be used is as follows:
q = m  C  T
Where:
q is the actual heat content of the system measured in Joules
C is something called the “specific heat” of the system
And T is the temperature of the system measured in degrees Celsius.

5. So what is this “Specific Heat” ?
It is a nature-given characteristic of a pure substance – so it is a physical property.
It is defined as the amount of heat flow necessary to cause a 1 degree Celsius temperature change in exactly 1 gram of a pure substance.
As an example – it would be the amount of heat that would have to be added to 1 gram of water to cause the temperature to increase by exactly 1 °C.
For water, the specific heat is 4.18 J / g °C

6. So…
It would take the addition of 4.18 Joules of heat to cause 1.0 gram of water to change temperature by 1.0 degree Celsius.
Note that it does not matter where that 1 degree change is on a thermometer.

7. The Heat Pyramid q m C T