Dear Leela,

I suggest you to have a look at www.geopolymer.org it’s the site where professor Davidovits has collected the most important informations about Geopolymer technology.

Check at technical papers and GP Camp section , I hope you can find all answers at your doubts.

All best

Alex Reggiani

We should generally take not fully specified % concentrations as wt% ― where wt is often omitted or can be substituted by either wt., wt/wt, wt./wt., or m/m ― meaning: (mass of pure solute / mass of solution)·100%; even if this is not clearly stated. If is required to prepare the requested solution to exactly fullfil a given volume, the density of the solution for that same concentration, at a given temperature, should be known.

Example:

i)To prepare a 50 wt% NaOH aq. sol. from caustic soda flakes of (e.g.) 98.5% purity, we can weight (50/0.985) g of the flakes, to dissolve by adding pure water up to 100 g of solution, in a 100 g of solution basis.

ii) In practice, it is often found more convenient to measure the volume of solution, than to weight it; and we can note that 100 g of solution, would correspond to (100/|ρ|) cm3, where ρ stands for solution density (g/cm3). To obtain a volume V (cm3) of solution, (50/0.985)•[V/((100 g)/ρ)] g of the mentioned caustic soda flakes should be weighted.

iii) The solution density for 50 wt% NaOH aq. sol. is ρ = 1.5253 g/cm3 at 20 ºC (*).

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(*) R.H. Perry, D.W. Green, J.O. Maloney (Eds.), "Perry's Chemical Engineers’ Handbook", 7th ed., McGraw-Hill, 1997, Table 2.90.

iv) The prepared solution should still be standardized (by titration) if its concentration must be (more) accurately known. That is often the case for analytical chemistry work.