Would the calculated molarity of the unknown acid solution be higher, lower, or
ID: 496252 • Letter: W
Question
Would the calculated molarity of the unknown acid solution be higher, lower, or affected if each of the following occurred. Explain your answers. a. The buret containing NaOH was rinsed with distilled water but not rinsed with NaOH before being filled. b. Your lab instructor miscalculated the Molarity of the NaOH solution you used the titration (the true molarity was higher than calculated by your instructor). c. The tip of the NaOH buret contained an air bubble at the beginning of the titration but not at the end. Suppose you used an unknown H_2SO_4 concentration instead of HCI. What changes would need be made to the calculations of the concentration of the acid?Explanation / Answer
Hi
Formula for calculation of concentration of unknown acid: M1V1= M2V2
where subscript 1 represent acid and subscript 2 represent base.
1) a. The molarity of the unknown solution will not be affected, if the buret, rinsed with distilled water is allowed to dry. There shouldn't be no drop of water inside the buret. If there is water inside, it will take more volume of NaOH to neutralize the acid and so higher concentration of acid will appear in calculation.
b. The calculated molarity of acid will be less as the M2 decrease, M1 will decrease because M1 is directly proportional to M2.
c. Air bubble in buret affects the volume of NaOH in buret.So if there was air bubble in the beginning and no air bubble in the end, the volume of NaOH equivalent of air bubble has to be poured in titration and buret accounts for both the volumes; air volume and volume of NaOH equivalent of air bubble whereas, only one can be taken into account. So calculated molarity will be higher in this case.
2. No changes are required in calculation. You can use the same formula.
Thank you
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