when yo u were transferring the mass of sodium chloride you measured to Test Tub

Question

when yo u were transferring the mass of sodium chloride you measured to Test Tube 2, a small 2 Assume thte weighing paper, so the actual mass of NaCl you added to the tube was a amount rem than the mass you a The freezing point depression that you measured thought you transferred. Describe how this error would affect each of the following values. b The molality that you calculated from your measurement of the freezing point depression e The molar mass of NaCI that you calculated from the molality that you determined d The actual molality of the solution. e The expected freezing point depression. 3 Describe how a minor error at the beginning of an experiment can affect your final results a Consider the procedure you performed in this lab activity. What is one other possible measurement error a student could make? Following the framework in question 2, describe how this error would propagate through the subsequent measurements and data analysis in the experiment b Exploring General Chemistry in the Laboratory

Explanation / Answer

Let the original sample of Nacl be x grams

Now the amount of sample left be y grams

Total sample taken=x-y grams

Now,we know that

Moles directly proportional to mass,which is directly proportional to the molality

As the sample,remains on the paper the weight of Nacl decreases

Hence,

a.

TF = KF · M.i

TF= freezing-point depression

KF= the cryoscopic constant

M is the molality (moles solute per kilogram of solvent)

i is the van 't Hoff factor

TF Molality   Mass

Freezing point depression measured will be more than the actual one(as the mass was left on the filter paper)

b. Molality

Molality   Mass

Hence,Molality measured is more than actual one

c. Molar mass is remains constant as it is independent of the actual mass.

d. Molality

Molality   Mass

As the mass decreases,molality decreases

e. Freezing point depression

TF = KF · M.i

TF= freezing-point depression

KF= the cryoscopic constant

M is the molality (moles solute per kilogram of solvent)

i is the van 't Hoff factor

TF Molality   Mass

Hence,Freezing point depression decreases wrt original sample

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