Remundo wrote: from
https://www.econologie.com/forums/palamares- ... 83-90.htmlCapt_Maloche wrote:Yes i do in bold
Here, if you have 2 minutes
you could not find me the volumetric production ratio between the mass of water and H2 + O2 for an electrolysis? I don't know where I put it
so you will remind me how we use the mendeleiev table
Water has a density of 1000 kg / m3
1 mole of water has a mass of 18g / mol
H2 and O2 are formed in the gaseous state with 2 moles of H2 for one mole of O2
Each of these gases follows the PV = n RT law with:
R = 8.314 J / K / mol, T in kelvin, n number of moles in a volume V
The rate of formation of H2, O2 products is linked to the electrolysis current (Faraday's law + water electrolysis).
Go Maloche, an effort ... And this water condenser?
Correction following the Response of Com pPFFF
Well then, let's take 1L (1kg at 20 ° C) of water
1mole H2O gives 1mole of H2 + 1 / 2mole of O2
molar mass of H2O 18g / mol
molar mass of H 1.008g / mol and H2 2.016 g / mol
molar mass of O 16g / mol and O2 32g / mol
1000g of water gives 1000/18 = 55,555 mol of H2O
be broken down into
55.555 x 1 = 55.555 mol of H2 i.e. 55.555x2g = 111.111g of H2
et
55.555 x 1/2 = 27.777 Mol of O2 or 27.777x32g = 888.888g of O2
Good, and after?
PV = n RT where V = nRT / P
p is the pressure (in pascal);
V is the volume occupied by the gas (in cubic meters);
n is the quantity of material, in mole
N is the number of particles
R is the universal constant of perfect gases
R = 8,314 472 J · K-1 · mol-1
we actually have R = NA · kB where NA is the Avogadro number (6,022 × 1023) and kB is the Boltzmann constant (1,38 × 10-23);
T is the absolute temperature (in Kelvin).
OK then
V of H2 = 55.555x 8,314 472 x (20 + 273) / 101 325 = 1.3356 m3 (1336L what)
and to check
V of O2 = 27.777 x 8,314 472 x (20 + 273) / 101 325 = 0.668m3 (668 L what)
I also know that: Rho of H2 = 0,08988 kg.m-3 and Rho of O2 = 1,43.10-3 g.cm-3 to 20 ° C and
http://lycees.ac-rouen.fr/galilee/oxygene.htmFor hydrogen:
the PCS is: 12,745 106 J / m3 is 286 kJ / mole
And the PCI is worth: 10,8 106 J / m3 is 242 kJ / mole
Either about 2h production with 2200W efficient or 0.5L / h
Interesting to measure the efficiency of electrolysis
source:
http://uuu.enseirb.fr/~dondon/devdurabl ... stible.htm3.3 Rounded energy balance of the decomposition of a water molecule:
H2O -> → H2 + ½ O2
The H2O water molecule consists of 2 OH bonds and each bond has a molar energy of 460 kJ (cf table § 2.2.4) which represents 2 x 460 = 920 kJ for one mole of water.
The breaking of the OH bonds of the water molecules for one mole of water requires the contribution of 920 kJ / mole (left side of the equation). However, the recombination of the hydrogen atoms H into H2 (gaseous hydrogen) produces an energy that comes, in the balance sheet, as a deduction from the previous one:
HH → H2 This recomposition brings 432 kJ / mole.
Likewise for the recomposition of the oxygen atoms:
½ OO → ½ O2 This reaction releases ½ x 494 kJ ie 247 kJ / mol.
The energy consumed for the dissociation operation of the water is finally:
920 - 432 - 247 = 241 kJ / mole
Thus the manufacture of 2 g of hydrogen by cracking of one mole of water (without taking into account the losses) requires the contribution of 241 kJ, ie 120.500 kJ to manufacture 1 kg of hydrogen.