Answer the following questions on a separate page. Using a stock titrant concent

Question

Answer the following questions on a separate page. Using a stock titrant concentration of 0.1000 mol/L NaOH, determine the NaOH concentrations prepared using the following dilutions: a) 1.25 dilution (10 mL pipetted in 250 mL volumetric flask) b)1:5 dilution (50 mL pipettd in 250 mL volumetric flask) During the quick titration of 10 mL of lemon juice with 0.1053 mol/L NaOH, a student dispensed 82 mL sodium hydroxide (titrant) into the lemon juice (analyte) before the end point was reached. Estimate the analyte concentration, assuming that the acid in the lemon juice is monoprotic. What should be diluted (titrant or analyte) in the titration described in Question 2 above? What dilution factor is necessary so that between 15 and 40 mL of titrant is used in the quantitative titration? See the procedure, pages 0-8 and 0-9 for possible dilutions.

Explanation / Answer

1. Dilution

concentration of NaOH solution,

a) 1 : 25 dilution

= 0.1 x 10/250

= 0.004 mol/L

b) 1 : 5 dilution

= 0.1 x 50/250

= 0.02 mol/L

2. Titration

moles of NaOH used = 0.1053 x 82

                                   = 8.6346 mmol

analyte concentration in lemon juice = 8.6346/10

                                                          = 0.86346 mol/L

3. The analyte muct be diluted for the given titration so that less amount of NaOH would be used for neutralization of the acid in the lemon juice.

The dilution factor that may be used for the analyte solution = 1 : 4

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