# Which kind of Heat?

I have two questions about heat. On the one hand I want to know the truly nature of heat, I mean: What is heat? Is effective energy or the transition of energy*? The phrase "Heat is one kind of energy" is confusing me, I mean heat is THE energy or the transition of energy? If you consider the second point of view, then, which means the ways of heat transfer(Like: radiation, conduction,convection)? We can say that "Heat Transfer" is a pleonasm (because Heat is a transfer method, in thermodynamics, then we would have: "Transfer Method of energy(Heat) Transfer")?

*If we think in terms of the notion of Work (mechanical) we can easily notice that Kinetic Energy is THE energy and Work (mechanical) is the "method" such that kinetic energy is transfered. And if we think in this way (is it the real,precise and formal point of view of nature of the work?) then we can say that heat is simply a "Thermodynamical Work"

On the other hand, I'm still confused about therms, physical meanings and formulas. I'm going to explain:

1) Which means Specific Heat? 2) Which means Sensitive Heat? 3) Which means Latent Heat? 4) Which means heat capacity?

By 1),2),3),4) I want to know the relationship between these definitions, I mean: sometimes we have books saying that Specific heat is equal to specific heat, sometimes the books presents a distinction or even calling by Specific Sensitive Heat; In terms of Formulas we have:

-For Specific Heat (Sensitive heat? Specific Sensitive Heat?): $c = \frac{C}{m\Delta T}$ ; $c = \frac{\Delta Q}{m}$

-For Latent Heat: $\Delta Q = m.L$

-For Sensitive Heat: $\Delta Q = m.c.\Delta T$

-For Heat Capacity: $C = \frac{\Delta Q}{\Delta T} ; C=mc$

** Obs: Ok, I know that is just algebraic manipulation and eventually we can easily see that one thing is equal to another. But, some times specific heat appears in one formula and another in different types of heat; I want to know the difference between:

These two formulas: $C = \frac{\Delta Q}{\Delta T} ; C=mc$

These two formulas: $c = \frac{C}{m\Delta T}$ ; $c = \frac{\Delta Q}{m}$

I know that I'm quite lost.

I've never been let down by the definition "Heat is energy transferred by virtue of a temperature gradient.".

Using 'energy transferred' rather than "energy transfer" allows us to speak of "the flow of heat" without too much pleonasm.

I'd avoid calling heat "thermodynamic work"; this way lies confusion. But I do agree that heat, like work, is energy (being) transferred. Contrast with internal energy. [I'm thinking of heat, work and internal energy as the three terms in the First Law of Thermodynamics.]

I've never come across the term "sensitive heat": are you translating into English from another language?

What we now call 'specific heat capacity', c, used to be called just 'specific heat' (at least it did in the UK). In this context 'specific' means per unit mass. C in your equations is the heat capacity for any sample of material, so for a sample of mass m, C = mc. Note that the terms heat capacity and specific heat capacity are not ideal, as the sample of material doesn't contain heat; it contains internal energy. But the equations you quote (except for the last pair) are fine, with the Q in the equations representing the heat (as defined above) entering the material. The last two equations you quote are wrong, or the symbols don't have their usual meanings.

I hope this helps with some of the points you've raised in your interesting post. You'll no doubt wish to probe further…

Later addition: the c, C and L that appear in your equations aren't then, different kinds of heat, but are constants for the material, telling us, if you like, something about what happens to the material when it is given heat!

• Hi, yes I'm translating "sensitive heat" from portuguese. – M.N.Raia May 28 '17 at 11:22
• BTW "Sensitive heat" is almost definitely "sensible heat". – JMac May 28 '17 at 12:01
• Agreed, but what is the distinction between heat and sensible heat? – Philip Wood May 28 '17 at 16:51
• I've added a few other remarks to my original answer. In particular, I think the last two equations you quoted are wrong, or the symbols in them aren't being used to stand for the things they usually stand for. – Philip Wood May 29 '17 at 8:12
• For the sake of closure, I'd better say that I'm sceptical about whether 'sensible heat' has any meaning that can stand up to scrutiny. – Philip Wood May 30 '17 at 20:46