What is Specific Heat?

specific heat equation

Core Concepts

In this chemistry 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

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 thermal energy needed to raise the temperature of an object. When talking about pure substances of any varying amounts, the specific heat capacity of that substance is used, which is the amount of heat required to raise the temperature of one gram of that substance by one degree Kelvin. Ice has a specific heat capacity, but an ice cube can have its own specific heat. Specific heat capacity is usually measured in Joules per gram per degree Celsius (J/g oC).

Each substance has their own specific heat capacity, which is a numerical value that describes this chemical property! For example, the specific heat of copper is 0.385, which is quite low. It means that a piece of copper is quite easy to heat up.

Specific Heat Formula

You can further learn the relationship between heat and temperature change through the following equation:

    \begin{gather*} {Q=mc\Delta T} \end{gather*}

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.

    \begin{align*} {Q&=mc\Delta T} \\ {Q&=\left( 100g\right) \left(0.128\frac{J}{g\degree C}\right) \left( 37\degree C - 25\degree C\right)} \\ {Q&=\left( 100\right) \left( 0.128\right) \left( 12\right) = 153.6J} \end{align*}

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 specific heat capacity of water is associated with the unit called the calorie. In fact, one calorie is defined as the amount of energy 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?

Water has a high heat capacity because of strong intermolecular interactions. In fact, it is the highest heat capacity 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 then break the hydrogen bonds between water molecules.

Practice Problems

Problem 1

A 50g sample of metal is heated with 800 joules, increasing its temperature by 41.6oC. What is the identity of the metal?

Problem 2

How many joules of energy of you need to raise 500g of aluminum by 20oC?

Problem 3

You heat a 1.2kg sample of copper at 25oC by 900J. What is the final temperature of the sample?

Practice Problem Solutions

1: Copper

2: 9000J

3: 27oC

Further Reading