How could latent heat be explained from the graph? Explain in detail
Answers
You know that ice can melt into water. You also know that ice doesn’t melt into water when it’s inside your freezer.
This means ice can only melt once it reaches a particular temperature. Under 1 atm pressure, pure ice melts at a 0 degrees C.
But Ice can’t melt just like that. If you hold ice in your hand, you feel cold while it melts. Thus it’s taking heat energy from your body to melt. And while it melts the temperature remains a constant.
For a while, people didn’t quite get this. The notion was, when you heat something the temperature must rise. (I am pretty sure a lot of people with no proper physics training still have that notion). So it didn’t make sense as to where the ‘heat’ went. So they thought it was hiding all the while when the ice melted, because once it melted, the temperature would rise back up again.
The latin word for hidden is latent :)
So now you can begin to realize what latent heat really is. It is that apparently ‘hidden heat’ that goes into the ice, but doesn’t increase the temperature.
You can find the same phenomenon while the water crystallizes (solidifies) to form ice. This ‘hidden heat’ is given back.
Today we know it’s not really hidden. The heat was needed to increase the kinetic energy of the water molecules, which allowed it to free themselves and flow freely. Ergo, converting a solid to liquid requires energy (even though the temperature doesn’t change)
For convenience we just define the latent heat as the amount of heat needed per kilogram of an object to melt at it’s melting point.
But it’s not just melting or crystallizing. The same applies to vaporization or condensation or even sublimation
