I'm currently conducting experiments where I place sealed silica ampules containing atmospheric air and different powder mixtures into a vertical tube furnace at 1000°C. Only the bottom parts of the silica tubes are exposed to the 1000°C, while the upper parts of the tubes are as cool as ~100°C during my syntheses. The goal of my experiments is to degas these powder mixtures, which then percolate upwards as gases in the ampules and then recrystallize on the silica tube's surface again as they cool down. In some experiments I'm facing problems however, that the gas pressure is too big for these ampules and that they're destroyed upon quenching. For that reason, I want to estimate the maximum gas volumina and gas pressures that could possibly be reached in those ampules. For my approach, I have defined the major expected gas species in the ampules and know the mass of my starting powder mixture, which are presented below:
CuSO4*5H2O = 0,3895 g
CuO = 0,0414 g
NaCl = 0,0304 g
KCl = 0,0388 g
Expected gases: H2O(g), H2S(g), O2(g), SO2(g), SO3(g), HCl(g), NaCl(g), KCl(g) and CuCl2(g)
I know that you can calculate the gas pressure of an individual gas phase based on the ideal gas law, but for that I need the substance amount of the respective gas phase. However, I don't know how much of these gases form in the given volume and what their respective volume percentages are, so I assume that 1. All of my starting material degases and 2. That I can calculate for every gas species individually its maximum substance amount (meaning: If I want to consider only the substance amount of O2, I use up all of the oxygen in my CuSO4*5H2O and all of the oxygen in my CuO). Now what I do not know however, is how to calculate the total substance amount based on the mass of my starting powders. I know that you can calculate it normally if you divide the mass by its molecular weight, however, I'm not quite sure how to consider the oxygen in CuSO4*5H2O on its own. My calculation for the O in the copper sulfate for example looks as followed:
1. CuSO4*5H2O = 249,68 g/mol and O = 16 g/mol
2. CuSO4*5H2O = 9 O or 4,5 O2
3. 4,5 * 32(molar mass O2)= 144 g/mol
4. (144 g/mol / 249,68 g/mol)*100 = 57,67%
5. 0,3895 g * 0,5767=0,224625 g for O2
6. 0,224625 g / 32 g/mol = 0,00701953125 mol
Is this calculation correct? And how do I combine the substance amount of O2 from CuSO4*5H2O and the O2 from CuO? Do I just add them up?
I hope my question has been understood. I'm coming from a geoscientific background so I have unfortunately little knowledge on some basic chemistry. So any help would be appreciated!