Answer:
0.109 g.
Explanation:
Equation of the reaction:
Na3PO4 + 3HCl --> 3NaCl + H3PO4
Number of moles of HCl = molar concentration × volume
= 0.1 × 0.04
= 0.004 mol.
By stoichiometry, 1 mole of Na3PO4 neutralises 3 moles of HCl. Therefore, number of moles of Na3PO4 = 0.004/3
= 0.0013 mol
Mass of Na3PO4 = molar mass × number of moles
= 0.0013 × 164
= 0.219 g
Since 50% of Na3PO4 was present in the sample. Let 100 g be the total mass of the substance
= 0.219 × 50 g/100 g
= 0.109 g.
Answer:
A3B3
Explanation:
Molecular formula = n x empirical formula
(AB) n = 90
MM of AB = 30 g/mol
30n = 90
Divide both side by the coefficient n i.e 30
n = 90/30 = 3
Molecular formula = n x empirical formula
Molecular formula = n x (AB)
Molecular formula = 3(AB) = A3B3
The answer to this is to prevent dilution of the base, which may affect the results. I think that is right.
