In this tutorial, you will be introduced to the topic of specific heat. In addition, you will learn the formula that goes along with this concept and go through an example to work out the math. Also, you will learn a list of multiple substances’ specific heat capacity.
Topics Covered in Other Articles
- Chemical Reactions Made Easy
- States of Matter
- Physical & Chemical Properties
- Properties of Solids, Liquids & Gases
Specific Heat Definition
How easy it to heat a substance? Do all substances require the same amount of heat to raise their temperature?
An observation made by scientist Joseph Black stated that in order to heat equal masses of different substances through the same temperature interval, distinct amounts of energy are required. By the way, Joseph Black is best known for his experiments with carbon dioxide, calling the gas “fixed air”.
This chemical property, known as specific heat, is defined as the amount of heat needed to raise the temperature of 1 gram of a substance by 1 degree Celsius. Specific heat is usually measured in Joules per gram per degree Celsius (J/g oC)- but can also have the unit ‘calorie’.
Each substance has their own specific heat capacity, which is a numerical value that describes this chemical property!
Specific Heat Formula
You can further learn the relationship between heat and temperature change through the following equation:
Q= heat added (Joules)
m= mass (grams)
c= specific heat (J/ g oC)
ΔT= change in temperature (Tfinal – T initial)
*Although this concept has to do with temperature in Celsius, it is okay if the ΔT value is in a different unit of temperature. This is because the difference between the two temperatures will be the same no matter the unit!
This relationship is only valid when there is no phase change, meaning the substance stays in the same state of matter from beginning to end. Gains or losses of heat that result in a phase change, such as melting or freezing, have other equations; click here to learn more!
Specific Heat Equation Example
Q: What is the energy, in Joules, needed to heat a lead pipe weighing 100g from 25oC to 37oC? The specific heat capacity of lead is 0.128 J/g oC.
A: Use the equation & plug in the numbers given to find the answer.
Q= (100 g)(0.128 J/g oC)(37oC -25oC)= (100)(.128)(12)
Q= 153.6 Joules
Specific Heat Capacities – Examples
The units are joules per gram per degree Celsius.
- Water = 4.186 J/g oC (or 1 calorie)
- Dry air = 1.01J/g oC
- Ice = 2.05 J/g oC
- Aluminum = 0.900 J/g oC
- Alcohol = 0.508 J/g oC
- Copper = 0.385 J/g oC
- Lead = 0.128 J/g oC
Can specific heat be negative? Not as far as we know on this planet, but possibly in some stars or gas clouds.
Heat Capacity of Water
The S.H capacity of water is associated with the unit called the calorie. In fact, one calorie is defined as the amount of heat need to raise 1 gram of liquid water one degree Celsius. The calorie was first used by Nicolas Clement in the early 19th century. It comes from the Latin word “calor” meaning heat.
Why does water have a high specific heat?
It is because of the hydrogen bonds. It fact, it is the highest S.H. of all liquids. Because water is a polar molecule, with a large electronegativity difference between hydrogen and oxygen, hydrogen bonds form between the positive hydrogen atoms in one molecule, and the negative oxygen atoms in nearby molecules. It takes a lot of energy to loosen and break the hydrogen bonds between water molecules. This is the reason that oceans cool down slower than land does.