3NaOH + H3PO4 ==> Na3PO4 + 3H2O
mols NaOH = grams/molar mass = 4.0/40 = 0.1 mol.
a) M NaOH = mols/dm3 = 0.1mol/0.1 dm3 = 1M
b) From the equation, 3 mol NaOH = 1 mol H3PO4; therefore, 40 cc (0.04 dm3) of NaOH x 1 M = 0.04 mols NaOH.
mols H3PO4 = 1/3 of that or 0.04/3 = about 0.0133 mols.
Then M H3PO4 = mols H3PO4/dm3 H3PO4.
100cm^3 of a sodium hydroxide,NaOH solution contains 4.0g of solid sodium hydroxide,NaOH.40 cm^3 of phosphoric acid,H3PO4 is needed to neutralise 40cm^3 of the alkali.(RAM:H,1;O,16;Na,23;P,31)
(a)Calculate the molarity of the sodium hydroxide,NaOH solution.
(b)Calculate the molarity of the phosphoric acid,H3PO4.
1 answer
1 answer