Question

How to convert mass percentages of oxides in to moles - g/mol?

I am a potter. I have a perfect ceramic glaze but I lost its weighing recipe. I had the glaze analyzed in a lab and I got a XRF analysis of the oxides. Unfortunately the readings are in mass percent - m-% or w/w. In order to get a raw material recipe for the glaze - by using the Seger formula - I need to have the readings in moles (g/mol).
Here is the list of oxides:
Na2O - 0,43 MgO - 0,13 Al2O3 - 2,534 SiO - 16,345
K - 3,58 CaO - 10,69 TiO2 - 6,07 Fe2O3 - 0,22
CuO - 0,01 ZnO - 10,95 SrO - 0,02 SnO2 - 0,03
PbO - 0,04 SO2 - 0,01 Rb2O - 0,01 ZrO2 - 0,01
I need help on how to convert mass percentages of oxides in to moles. Could someone help me with this?

Answer 1

Warning! Long Answer. Here's what I get.

Explanation:

The formula

Potters express the formula of a glaze by the mass percent of its component oxides.

Here is your analysis in the form of a table.

`bb(color(white)(m)"Fluxes"color(white)(ml)"Intermediates"color(white)(mll)"Glasses")`
`ulbb(color(white)(mll)"MO"color(white)(mmmml)"M"_2"O"_3color(white)(mmmml)"MO"_2color(white)(mm))`
`"Na"_2"O" color(white)(m)0.43color(white)(mll)"Al"_2"O"_3color(white)(m)2.53color(white)(mm)"SiO"_2color(white)(m)16.34`
`"MgO"color(white)(ml) 0.13color(white)(mll)"Fe"_2"O"_3color(white)(m)0.22color(white)(mll)"TiO"_2color(white)(mll)6.07`

`"K"_2"O"color(white)(mll)3.58color(white)(mmmmmmmmmll)"SeO"_2color(white)(ml)0.01`
`"CaO"color(white)(m)10.69color(white)(mmmmmmmmmll)"ZrO"_2color(white)(ml)0.01`
`"CuO"color(white)(mll)0.01color(white)(mmmmmmmmmll)"SnO"_2color(white)(m)0.03`

`"ZnO"color(white)(ml) 10.95`
`"SrO"color(white)(mm)0.02`
`"PbO"color(white)(mll)0.04`
`"Rb"_2"O"color(white)(m)0.01`

Formula Masses

All formulas have a relative formula mass `"M_text(r)`. Here are the calculations.

`ulbb("Oxide"color(white)(mll)"Calculation"color(white)(mmmmll)M_text(r)`
`"Na"_2"O"color(white)(mmml)2×23.0+16.0 =color(white)(ml)62.0`
`"MgO"color(white)(mmmmmll)24.3 + 16.0 =color(white)(ml)40.3`
`"Al"_2"O"_3color(white)(m)2×27.0+3×16.0 =color(white)(m)102.0`
`"SiO"_2color(white)(mmmll)28.1 + 2×16.0 =color(white)(mll)60.1`
`"K"_2"O"color(white)(mmmll)2×39.1+16.0 =color(white)(mll)94.2`

`"CaO"color(white)(mmmmmll)40.1 + 16.0 =color(white)(mll)56.1`
`"TiO"_2color(white)(mmmll)47.7 + 2×16.0 =color(white)(ml)79.7`
`"Fe"_2"O"_3color(white)(m)2×55.8+3×16.0 =color(white)(m)159.6`
`"CuO"color(white)(mmmmmlll)63.5 + 16.0 =color(white)(ml)79.5`
`"ZnO"color(white)(mmmmmm)65.4 + 16.0 =color(white)(mll)81.4`
`"SeO"_2color(white)(mmmll)79.0 + 2×16.0 =color(white)(m)111.0`

`"Rb"_2"O"color(white)(mmml)2×85.5+16.0 =color(white)(m)187.0`
`"SrO"color(white)(mmmmmml)87.6 + 16.0 =color(white)(m)103.6`
`"ZrO"_2color(white)(mmmll)91.2 + 2×16.0 =color(white)(m)123.2`
`"SnO"_2color(white)(mmm)118.7 + 2×16.0 =color(white)(m)150.7`
`"PbO"color(white)(mmmmml)207.2 + 16.0 =color(white)(m)223.2`

These numbers are not grams: they are relative molecular masses.

For example, they tell you that a "particle" of `"ZnO"` has twice the mass as one of `"MgO"`.

Converting to moles

To convert to moles, you divide the mass of each oxide by its molar mass.

The Seger formula is a "unified" formula, so you get more useful numbers by multiplying the number of moles by 100.

For example,

`"Moles of CaO = 10.69/56.1 × 100 = 19.06"`

`bb(color(white)(mll)"Fluxes"color(white)(mm)"Intermediates"color(white)(mml)"Glasses")`
`ulbb("MO"color(white)(m)"Moles"color(white)(m)"M"_2"O"_3color(white)(m)"Moles"color(white)(m)"MO"_2color(white)(m)"Moles")`
`"Na"_2"O" color(white)(m)0.69color(white)(mm)"Al"_2"O"_3color(white)(mm)2.48color(white)(mm)"SiO"_2color(white)(mm)20.19`
`"MgO"color(white)(ml) 0.32color(white)(mm)"Fe"_2"O"_3color(white)(mm)0.14color(white)(mm)"TiO"_2color(white)(mml)7.62`

`"K"_2"O"color(white)(mll)3.80color(white)(mmmmmmmmmmm)"SeO"_2color(white)(mml)0.01`
`"CaO"color(white)(m)19.06color(white)(mmmmmmmmmmm)"ZrO"_2color(white)(mml)0.01`
`"CuO"color(white)(mll)0.01color(white)(mmmmmmmmmmm)"SnO"_2color(white)(mm)0.00`

`"ZnO"color(white)(ml) 13.45`
`"SrO"color(white)(mm)0.02`
`"PbO"color(white)(mll)0.02`
`"Rb"_2"O"color(white)(m)0.00`