Chemistry
posted by Merlina .
how to prepare and calculate 10%,20% and 30% of phosphoric acid from the concentrated? Meaning that if 10% = 10%phosporic acid+90% of water. let say i want to prepare in volume of 250ml.
given,
Formula: H3PO4
Melting point: 42.35 °C
Density: 1.88 g/cm³
Molar mass: 98 g/mol

I don't get it. What's to calculate?
10% phosphoric acid = 10g H3PO4 + 90 g H2O or 10g/100 g soln. You want about 250 grams of solution so
10g x (250/100) = 25 g H3PO4
This won't be exactly 250 mL; you could take that into account if you knew the density of the 10% solution. 
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