# What are the differences between specific latent heat and latent heat?

What are the differences between specific latent heat and latent heat?

As far as I know, latent heat is the heat required or released during the change of state, without change of temperature. So what does specific latent heat mean? Are they the different? If yes, what does the term 'specific' contribute?

• Latent heat is heat is per mole of substance - specific latent heat is heat per unit mass. It's typically easier to detect patterns in different substances when using heat/mole. – Cinaed Simson Apr 17 at 5:05

In this context the word specific means per unit mass.

So if a lump of ice has a specific heat, the specific latent heat of ice is the latent heat of the lump of ice divided by the mass of the ice.

In the same way if a lump of copper has a heat capacity then the specific heat capacity of copper is the heat capacity of the lump of copper divided by the mass of copper.

In the field of electricity you might refer to the charge of an electron $$e$$ and the specific charge of an electron $$\frac em$$.

• I thought "latent heat" was always per unit mass so that "specific latent heat" would be redundant. No? – Bob D Jan 13 at 13:49
• @BobD Latent heat by itself refers to an object/body etc just as heat capacity. Adding the work specific is equivalent to adding the words "per unit mass". Thus specific latent heat is the latent heat per unit mass. I ave added another example in my answer. – Farcher Jan 13 at 13:55
• @Farcher what is specific heat? – Fred Weasley Jan 14 at 10:25
• Specific heat is the amount of heat required to raise (or lower) the temperature of a substance by one degree. Heat capacity is the amount of heat required to raise (or lower) the temperature of an object by one degree. – Farcher Jan 14 at 11:11
• @FredWeasley Correct - the input/outpuf of heat occurs at a change of state which for a pure substance occurs without a change of temperature. – Farcher Jan 15 at 11:38

the specific latent heat means the latent heat per unit mass of the substance in question.

According to the international standard ISO 80000-1 – Quantities and units, (which includes the quantities used as the basis of the units of the SI), the term “specific” is defined as follows:

The adjective “specific” is added to the name of a quantity to indicate the quotient of that quantity by mass.

A similar definition can be found in IUPAC Quantities, Units and Symbols in Physical Chemistry (Green Book):

The adjective specific before the name of an extensive quantity is used to mean divided by mass.

For example, specific heat capacity $$c$$ is defined as heat capacity $$C$$ divided by mass $$m$$.

Likewise, the specific latent heat of vaporization, i.e. the specific enthalpy of vaporization $$\Delta_\text{vap}h$$ is defined as enthalpy of vaporization $$\Delta_\text{vap}H$$ divided by mass $$m$$. For example, the specific enthalpy of vaporization of water at a pressure of $$p=1\ \mathrm{bar}$$ is $$\Delta_\text{vap}h=2257.4\ \mathrm{kJ\ kg^{-1}}$$.

Note that a quantity defined as A/B is called ‘quotient of A by B’ or ‘A per B’, but not ‘A per unit B’ (contrary to some other answers).

Concepts

• latent heat - During the process of melting of the temperature remains constant the amount of heat needed to melt a solid of mass M maybe Written as q=mL L constant for a given material and surrounding condition L is called a specific latent heat of fusion/vaporisation the term latent heat of fusion/vapourization is also used to mean the same thing

so basically heat required to cause change of state when ice is kept at temperature above 0 it doesn’t instantaneously melt but absorbs the heat from sourounding and changes to liquid phase same thing is true when water is converted to ice the heat is given out .. so you can think of latent heat as hidden heat