# Specific volume and enthelpy of mercury

• jahanzebikram
In summary, the student is trying to determine the specific volume and enthalpy of mercury at 0.4 MPa and 55% quality. They believe that if some pointers are provided, they can solve the problem. However, they cannot find saturated mercury tables, so they are unsure if they have understood correctly.
jahanzebikram
Homework Statement
"Determine the specific volume and enthalpy of mercury at 0.4 MPa and 55% quality."
Relevant Equations
Q = m c dT
I have been away from thermodynamics for a while, and there is a young mechanical engineering student who asked my help in solving the question. For the life of me I am unable to solve this problem and I am at my wit's end.

I believe I can solve the problem if some pointers are provided. Also, do property tables (like steam tables) for mercury exist?
If nothing else, then can I be directed towards the relevant study material? Any help is much appreciated.

jahanzebikram said:
Homework Statement:: "Determine the specific volume and enthalpy of mercury at 0.4 MPa and 55% quality."
Relevant Equations:: Q = m c dT

I have been away from thermodynamics for a while, and there is a young mechanical engineering student who asked my help in solving the question. For the life of me I am unable to solve this problem and I am at my wit's end.

I believe I can solve the problem if some pointers are provided. Also, do property tables (like steam tables) for mercury exist?
If nothing else, then can I be directed towards the relevant study material? Any help is much appreciated.
Well, I don't know if this helps (because I can't find "Satutrated Mercury Tables (liquid - vapor)", But let's pretend they do exist and it's just a matter of finding them.

To just refresh on the mechanics of that process: What do you get for the enthalpy of Saturated Water @ 4 Bar, 50% Quality?

erobz said:
Well, I don't know if this helps (because I can't find "Satutrated Mercury Tables (liquid - vapor)", But let's pretend they do exist and it's just a matter of finding them.

To just refresh on the mechanics of that process: What do you get for the enthalpy of Saturated Water @ 4 Bar, 50% Quality?
If I am not mistaken the enthalpy of Saturated water @ the given properties should be determined like this:

@ 4 bar
hf = 604.68 kJ/kg
hg = 2737.63 kJ/kg

so at x = 0.5

h = (1-x)hf + (x)hg
h = (0.5)604.68 + (0.5)2737.63
h = 1671.155 kJ/kg

but after a lot of googling, I have been unable to find saturated mercury tables so maybe there is some different way of finding out the solution that I don't have any idea about. Like I said, I have been away from thermodynamics for a while, and this question seemed like something I should be able to solve but can neither find head nor tails of it.

erobz
Chestermiller said:
After being unable to hone the powers of "lord google", I turn to you to get me out of this sticky problem.

No expert, but a few thoughts about finding the specific volume.

Presumably we take 0.4MPa (about 4 atm) to be the vapour pressure. In this case, the system’s temperature can be read-off this graph:
https://i.stack.imgur.com/StSNl.gif

The graph is Figure 1 from this pdf document: https://www.physics.rutgers.edu/~eandrei/389/NISTIR.6643.pdf

We now know the temperature and pressure of the vapour and we can find its specific volume (e.g. maybe using the ideal gas equation, else Van der Waals equation with the appropriate constants for mercury).

We can easily find the specific volume for the liquid phase. So the overall specific volume can be determined.

Not sure if that is what’s intended though. Seems a bit convoluted!

And if I’ve misunderstood something, I’m sure someone can correct me.

Lnewqban

## 1. What is specific volume?

Specific volume is the ratio of volume to mass of a substance. It is a measure of how much space a certain amount of a substance occupies.

## 2. How is specific volume of mercury calculated?

The specific volume of mercury can be calculated by dividing the volume of a given amount of mercury by its mass. This value can also be obtained from tables or graphs that show the relationship between specific volume and temperature or pressure.

## 3. What is enthalpy?

Enthalpy is a thermodynamic property that represents the total energy of a system. It includes both the internal energy and the energy required to overcome the pressure-volume work.

## 4. How is enthalpy of mercury determined?

The enthalpy of mercury can be determined experimentally by measuring the heat absorbed or released during a physical or chemical change of the substance. It can also be calculated using thermodynamic equations and data.

## 5. How does specific volume and enthalpy of mercury change with temperature and pressure?

The specific volume of mercury decreases with increasing temperature and pressure. On the other hand, the enthalpy of mercury increases with increasing temperature and pressure. This is due to the change in molecular interactions and the amount of energy required to overcome these interactions.

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