pre lab help? Experiment AN INSTRUMENTAL ANALYSIS OF POP FOR ITS PHOSPHORIC ACID

Question

pre lab help?

Experiment AN INSTRUMENTAL ANALYSIS OF POP FOR ITS PHOSPHORIC ACID CONTENT he re- Lab student performs an experiment for the determination of phosphoric acid (HPO) nt in a cola soft drink. A 0.5 milliliters sample of coa is diluted to 125 mL measured absorbance is 0.262. Using a graph of absorbance versus H,PO, concentration, the student determines that the diluted cola solution has a concentra- tion of 15.5 x 106 moles /liter: a) Calculate the total moles of H,PO present in 125 mL of solution with concentration 15.5 x 10 moles/liter. Volume (in lihers) x concentration( moe/ie)moles of solute b) How many moles of H PO, are present in 0.5 mL of the undiluted cola. Only water is added in the dilution process. o) Calculate the concentration of solution. Recall: 0.5 milliliters 0.0005 Liters)

Explanation / Answer

a)

mmol of H3PO4 = MV = 125 * 15.5*10^-6 = 0.0019375 mmol

mol = 0.0019375*10^-3 moles = 1.9375*10^-6 mol

b)

moles remain, so

1.9375*10^-6 mol H3PO4

c)

[H3PO4] = mol / V =  (1.9375*10^-6) / (0.5*10^-3) = 0.003875 M of H3PO4

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