Explain if and why each of the following experimental errors will lead to an inc

Question

Explain if and why each of the following experimental errors will lead to an incorrectly high or an incorrectly low calculated molar concentration of NaOH or if it will have no effect on the calculated molar concentration of NaOH. A student washed his buret with soap and water and did a final rinse with deionized water, but did not condition the buret before filling it with the dilute NaOH solution for the first trial. The potassium hydrogen phthalate primary standard was dissolved in 100 mL of DI water instead of the indicated 50 mL of DI water. A student failed to notice an air bubble in the tip of the buret and simply recorded the initial volume of titrant and continues on with the titration. The NaOH was delivered in a continuous stream rather than drop-wise near the endpoint, so the student's solution was dark pink at the end of the titration. Explain if and why each of the following experimental errors will lead to an incorrectly high or all incorrectly low calculated molar concentration of the hydrochloric acid or if it will have no on the calculated molar concentration of the hydrochloric acid. A student was in a rush and did not take the time to get the bottom of the meniscus right at the line when pipetting the acid. The bottom of the meniscus was just below the calibration line when the student moved the pipet into the Erlenmeyer flask to deliver the acid. The NaOH was delivered in a continuous stream rather than drop-wise near the endpoint, sc student's solution was dark pink at the end of the titration.

Explanation / Answer

2. Effect of errors on concentration of NaOH calculated

a. If the buret was not condiitoned before with NaOh solution, the resultant solution poured inside would be of lower molarity and thus, higher volume of titrant would be used, which would give higher moles and higher molar concentration value at the end.

b. If the standard was more dilute than expected, lesser amount of NaOH would be used, moles would be low and so the molar concentration would also be low for NaOH.

c. Air bubble would give error in volume of NaOH dispensed and hence moles would be lower, giving lower molar concentration value for NaOH.

d. If more of NaOH was dispensed, moles would be higher and so the molar concentration would be higher for NaOH.

3. Error effect on molarity of HCl

a. If not all of HCl was dispensed, the molarity of HCl would be lower as volume is lower.

b. If more NaOH is used, moles would be higher and thus molarity of HCl would be higher.

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