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1)Two burettes are set up. The first contains 0.15M NaOH and the second contains

ID: 546668 • Letter: 1

Question

1)Two burettes are set up. The first contains 0.15M NaOH and the second contains an HCl solution of unknown concentration. The initial volume for the NaOH burette is 0.3 ml. The HCl burette reads 1.45ml. 10.2 ml of HCl is dispensed into the reaction flask and Phenolphthalein is added as an indicator.   At the end of the titration, The volume for the NaOH burette is 22.5 ml. The final volume for the HCl burette is 10.9ml.

a)What is the total volume of NaOH used in the titration?

b)How many moles of NaOH was used?

c)What is the total volume of HCl used in the titration?

d)What is the final concentration of the HCl solution?

Explanation / Answer

NaOH + HCl ---> NaCl + H2O

a) volume of NaOH consumed = 22.5 - 0.3 = 22.2 ml

b) no of mol NaOH reacted = V*M

     = 22.2*0.15/1000

     = 0.0033 mol

b) volume of HCl used in the titration = 10.2 ml

c) final concentration of the HCl solution = n/v = 0.0033/10.2*1000 = 0.323 M