2 Exp. 8 Acid-Base Titration PRELAB QUESTIONS 1. To help you succeed in this lab

Question

2 Exp. 8 Acid-Base Titration PRELAB QUESTIONS 1. To help you succeed in this lab, here are some common mistakes and deviations from the written procedure. Predict how the final result will be affected if each of the following is done (instead of the procedure as written). Here are some hints for how to think about these questions. For example, you know that when the student finishes the titration he will subtract the starting reading on that buret from the final reading to get the volume of solution used. Ask yourself, will he actually have dispensed that much reagent, or more, or less? If less solution has actually been dispensed than the buret indicated, ask yourself how the final result of the calculation will be affected because the value for the number of mL used in the calculation is too large? If he has dispensed the amount of solution that he has measured, ask yourself if it is, for some reason, too much or too little? For example, what if some of the solution goes onto the desktop instead of the titration flask. Then the volume of the solution will be greater than it should be. Ask yourself what effect will be on the final result if the number of mL for that particular reaent is too large? Imagine putting a too large (or too small, number into the calculations Ask yourself what that does to the calculation? Beware, not all things mentioned will change the results. Put a check mark in the correet column Result Result Result too ok too a One student cleaned and dried his Erlenmeyer flask before each titration. b | Another student simply rinsed his flask with deionized water. I ? c Another student rinsed his Erlenmeyer flask with the standard d In part A, another student failed to bleed all the air out of the e After another student standardized his NaOH solution against HCl solution before he dispensed the acid solution into it to start the titration stopcock and tip of the buret and some air bubbles came out along with standard acid solution. an HCl solution of known concentration, he emptied the acid buret, but instead of rinsing it with his unknown acid solution, he rinsed it with water and then filled it with the unknown drops of NaOH solution clinging to the side of the ErlenmeyerV flask which titration of the unknown acid, a student left several never got down into the reaction mixture

Explanation / Answer

Result too large Result ok Result too small One student cleaned and dried the Erlemeyer flask before each titration x Another student simply rinsed with deionised water x Another student rinsed his flask with Std HCl before he dispensed the acid solution into it to start the titration x In first part another student failed to bleed all the air out of the stopcock and tip of the buret and some air bubbles came out along with standard acid solution x Ater another student standardized his NaOH solution against an HCl solution of known concentration, he emptied the acid buret, but instead of rinsing it with his unknown acid solution, he rinsed it with water and then filled it with the unknown acid x During titration of the unknown acid, a student left several drops of NaOH solution clinging t the side of the Erlenmeyer flask which never got down into reaction mixture x

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.