Question

Given this scenario:

1) If you dilute a solution by pipetting 10 mL of a pink solution into a 50 mL volumetric flask and you blow out the last drop from the pipet, then you dilute the solution until you reach the . 50 mL mark in the volumetric flask with water and mix it. The measured value for the absorbance should be _______ than the correct value?

a) greater

b) less

c) equal to

2) If you prepare a calcium carbonate solution and you add 4.00 mL of 4.00 M HCl, instead of 3.00 M HCl. You perform the experiment correctly except you used the 3.00 M HCl in your calculation. The reported value of calcium carbonate in the tablet will be _____ than the correct value. How will it effect the calculations?

a) greater

b) less

c) equal to

3) Does activation energy of a chemical reaction depend on the temperature?

Answer 1

#1. The pipet is calibrated such that it delivers the given volume without blowing last drop. If you blows that last drop from pipet then you are adding that extra volume (that last drop is extra) .

Thus if you are adding extra volume of pink sample solution , then concentration of solution prepared will also more than actual and absorbance is directly related to concentration. Thus absorbance will also more than correct value.

Option (a) greater , is the correct answer.