A typical formulation for window glass is 75% SiO2, 15% Na2O, and 10% CaO by mass.?

Question

A typical formulation for window glass is 75% SiO2, 15% Na2O, and 10% CaO by mass.

What masses of sand (SiO2), sodium carbonate, and calcium carbonate must be combined to produce 1.00 kg glass after CO2 is driven off by thermal decomposition of the carbonates?
(Express your answers to 1 decimal place.)

Mass of sand (in grams) 1.-----
Mass of sodium carbonate (in grams) 2.-----
Mass of calcium carbonate (in grams) 3.-----

Answer 1

This is something that is done by glass makers who mix their own batch (glass mix) with other ingredients added in. That doesn't mean it is easy. In this case, your formula begins with
1kg = 1000g = 750 g SiO2 + 150 g Na2O + 100 g CaO
Since the SiO2 doesn't change that is easy = sand
150 g Na2O has to come from Na2CO3 so for each mole of Na2CO3, we have to throw away one CO2 - if you work through the molecular weights (or refer to Glass Notes) Na2O is .585 of Na2CO3 so to get that much Na2O we invert to get 1.709x or 256.35g
100g CaO comes from CaCO3 so again we are throwing away one CO2 - if you work through the molecular weights (or refer to Glass Notes) CaO is .56 of CaCO3 so we invert and need 1.786x to get our CaO, or 178.6g.
so answers are 750g sand
256.4g sodium carbonate
178.6g calcium carbonate