A test procedure requires 500mL of a 4N phosphoric acid solution. The concentrated phosphoric acid available has a specific gravity of 1.69 and an assay of 85%. How would you prepare this solution? (MW H3PO4 = 98) (Valence is 3)
We know that
normality = Molarity * valence
Given that
normality of the solution = 4 N
So, molarity of the solution = normality /valence = 4/3 = 1.333333 M
Volume of 4 N solution required = 500 mL = 0.5 L
Number of moles of H3PO4 = M*V = 1.333333 M * 0.5 L = 0.666667 mol
Mass of H3PO4 = moles * mol.wt. = 0.666667 mol * 98 g/mol = 65.33333 g
Given that
Mass percent = 85 %
Mass percent = mass of solute/mass of the solution *100
85 = 65.33333/mass of the solution * 100
Mass of the solution = 65.33333/85*100 = 76.86 g
Given that
specific gravity = 1.69
We know that
specific gravity = density of the solution/density of water
density of the solution = specific gravity * density of water
density of the solution = 1.69 * 1.0 g/mL = 1.69 g/mL
Volume of the solution = mass/density = 76.86 g/(1.69 g/mL) = 45.48 mL
Volume of water to be added = 500 – 45.48 = 454.52 mL
Procedure :
Take 454.52 mL of water into a 500 mL volumetric flask and then add slowly 45.48 mL of concentrated Phosphoric acid
A test procedure requires 500mL of a 4N phosphoric acid solution. The concentrated phosphoric acid available...
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Our chemist found a solution of 0.333M H3PO4 (phosphoric acid) and another of 1.05M NaOH (amazing what you can find in the belly of a ship) and so she did an enthalpy of neutralization reaction using 50.0mL of each solution. (Phosphoric acid is a triprotic acid; each mole of acid can yield 3 moles of H+ ions.) Using the CRC Handbook at hand, the density and specific heats of the final solution were found to be 1.11 g/mL and 3.81...
Our chemist found a solution of 0.333M H3PO4 (phosphoric acid) and another of 1.05M NaOH (amazing what you can find in the belly of a ship) and so she did an enthalpy of neutralization reaction using 50.0mL of each solution. (Phosphoric acid is a triprotic acid; each mole of acid can yield 3 moles of H+ ions.) Using the CRC Handbook at hand, the density and specific heats of the final solution were found to be 1.11 g/mL and 3.81...
Our chemist found a solution of 0.333M H3PO4 (phosphoric acid) and another of 1.05M NaOH (amazing what you can find in the belly of a ship) and so she did an enthalpy of neutralization reaction using 50.0mL of each solution. (Phosphoric acid is a triprotic acid; each mole of acid can yield 3 moles of H* ions.) Using the CRC Handbook at hand, the density and specific heats of the final solution were found to be 1.11 g/mL and 3.81...
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