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The table below gives the results of three titrations carried out with 0.200 M HCl to determine the molarity of a given NaOH solution using phenolphthalein as indicator. NaOH was taken in the burette and HCl was taken in a conical flask for the titrations The actual molarity of the prepared NaOH solution was 0.220 mol dm -3 . Which among the following could be the reason for the wrong value obtained in titration III?

Options

  1. ANumber of drops of phenolphthalein added to the titration flask was more in this titration
  2. BThe concentration of HCl was wrongly used as 0.250 M for the calculation of M NaOH
  3. CA few drops of NaOH solution were spilled outside the titration flask during titration
  4. DA few drops of the neutralized solution from titration II were left behind in the flask

Correct answer

C. A few drops of NaOH solution were spilled outside the titration flask during titration

Step-by-step solution

O H - = n O H - V O H - = n a c i d V N a O H = H C l V H C l V N a O H = 0.21 M < 0.220

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