Question

Pipets used for the transfer of samples of aqueous solutions are always rinsedwith a small portion of the solution to be used before the sample is taken. calculate the percentage error arising in an experiment when 1-ml, 5-ml, and 10-ml pipets are used for transfer and each pipet contains 5 drops of water adhering to the inside of the barrel. a single drop of water has an approximate volume of 0.05 ml

Answer 1

Answer: -

25%, 5% and 2.5% are the percentage error arising in an experiment when 1-ml, 5-ml, and 10-ml pipette are used for transfer.

Explanation:-

We are told that each pipette contains 5 drops of water adhering to the inside of the barrel.

We are also told that a single drop of water has an approximate volume of 0.05 ml.

Total volume of water adhering to the inside of the barrel = 5 x 0.05

                                                                                                    = 0.25 mL

This volume of water adhering to the inside of the barrel is the cause of error in an experiment.

Thus percentage error = $\frac{Total error}{Actual value}$ x 100

For 1 mL pipette,

Percentage error       = $\frac{0.25 mL}{1 mL}$ x 100

                                      = 25%

For 5 mL pipette,

Percentage error       = $\frac{0.25 mL}{5 mL}$ x 100

                                      = 5%

For 10 mL pipette,

Percentage error       = $\frac{0.25 mL}{10 mL}$ x 100

                                      = 2.5%