# How much energy is needed to melt 15 grams of ice to water at #0^.C# ?

##### 1 Answer

In Physics, when talking about energy in thermodynamics, we talk about heat.

Heat can be defined with the letter Q.

Where:

**Specific heat** is defined as the amount of heat that is needed to raise a 1kg mass by 1ºC/1K. Units

Liquid water has a very high Specific Heat Capacity. It is about 4180

To solve your problem, we will have to introduce a new concept, **phase change** . This happens when a substance goes through a change in state, in other words, it changes from liquid to solid , liquid to gas or gas to solid.

In your case, we are melting ice, which means the phase change will go from solid to liquid.

To calculate this you need a new concept, **Specific Latent Heat** (denoted with the letter L), which is the amount of heat that has to be supplied to a mass to change its phase. This can be calculated by:

**To solve your problem, we will have to break it into parts:**

- Heat needed to melt ice at 15ºC to 0ºC (still in solid state)
- Heat needed to melt solid ice at 0ºC to 0ºC liquid.

Before we start:

- Specific Heat of Ice (C)= 2108 J/(kg*ºC)
- Latent Heat of Ice (L) = 333*10^3 J/kg

Hence:

This means that to melt a 0.015kg ice cube to water at 0ºC you will need 4520.7 J of heat.