You might have noticed that if you are trying to boil a lot of water, it takes longer than if you only wish to boil a small amount of water. This is all because of something called heat capacity. Keep watching to learn more. Before we get into details, it is important to realise that there is a difference between heat and temperature. The heat is a way of describing how hot or cold an object is and is measured in degrees Celsius, whereas heat is a form of energy and is measured in joules. The more heat transfer to an object, the more its temperature will rise, so heat and temperature are related but they are not the same. So what is heat capacity? The heat capacity of a substance is defined as the amount of heat required to raise the temperature of a material by one degree Celsius. However, what is more useful for us to think about is the specific heat capacity of the substance. This is, as it says in the name, a little bit more specific. It is the amount of heat required to raise one kilogram of a material by one degree Celsius. Different materials have different known specific heat capacities, but we aren't always given a table like this, so we need to know how to calculate specific heat capacities ourselves. We have this equation, which can be written as symbols like this. The energy transferred is the heat energy absorbed or released. This equation can also be rearranged. To work out the temperature change, subtract the old temperature from the new temperature. Let's have a look at a problem. Pause the video and attempt to calculate the specific heat capacity of lead. How did you get on? The energy transferred is this. The mass is this. And the temperature change is 10 degrees Celsius, because it's this, take away this. Using the rearranged equation, substitute in the values and we get 128 joules per kilogram Celsius. Here is another practice problem. Pause the video and attempt to calculate the energy transferred to the lead. Did you get it right? We could divide by 1000 to turn the answer into kilojoules. Notice that the answer is negative this time. It's because we called the lead. The temperature change will always be negative if it is being called and positive if it is being heated. So there you have it. To summarize, specific heat capacity is the amount of energy needed to raise one kilogram of the substance by one degree Celsius. It's helpful because it allows us to work out how much energy we need to heat up or cool down the substance to a desired temperature. To calculate it, use the following equation.