Before approving your procedure, your advisor also wants to know how sensitive t

Question

Before approving your procedure, your advisor also wants to know how sensitive the method is, or the lowest limit of phosphate concentration that can be measured this way. The lowest mass of precipitate you can measure was from a sodium phosphate solution prepared by the following steps: a. 12.4 mL of a 1.0 mM solution is added to enough water to make 250.0 mL of dilute solution b. 26.6 mL of the dilute solution is diluted further to a total volume of 100.0 mL Work out the phosphate concentration (in M) needed to measure a precipitate.

Explanation / Answer

Na3PO4 (aq.) -------------> 3 Na+ (aq.) + PO43- (aq.)

Intial concentration of sodium phosphate = 1.0 mM

Conc. of phosphate = concentration sodium phosphate = 1.0 mM

Dilution formula, M1 V1 = M2 V2

Case(1)

1.0 * 12.4 = M2 * 250.0

M2 = 0.0496 mM

Concentration of phosphate = 0.0496

1 mM = 1000 M

So, 0.0496 mM = 49.6 M

Case (2)

0.0496 * 26.6 = M2 * 100.0

M2 = 0.0132 mM

Concentration of phsophate = 0.0132 mM

1 mM = 1000 M

So, 0.0132 mM = 13.2 M

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.