4. Let's suppose that during the freezing point depression experiment, you weigh out about 2.50 grams of solid unknown. Then you attempt to pour this unknown into the p-xylene solution, but you inadvertently spill some of your unknown onto the floor. Since you're in a hurry to get outside and enjoy the sunshine, you pretend nothing happened and run the experiment with whatever unknown actually made it into the p-xylene. How would this specifically affect the calculated molecular weight of your unknown? Explain

4. Let's suppose that during the freezing point depression experiment, you weigh out about 2.50 grams of solid unknown. Then you attempt to pour this unknown into the p-xylene solution, but you inadvertently spill some of your unknown onto the floor. Since you're in a hurry to get outside and enjoy the sunshine, you pretend nothing happened and run the experiment with whatever unknown actually made it into the p-xylene. How would this specifically affect the calculated molecular weight of your unknown? Explain

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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QUESTIONS (Submit your answers on a separate sheet if necessary.) 1. If some of your unknown sample failed to dissolve completely, would the value of the molecular weight you calculated be too high, too low, or unaffected? Explain fully. 2. What would be the effect on the experimentally determined molecular weight if your sample contained a soluble impurity of higher molecular weight than the pure sample? Explain. 3. What would be the effect on the observed molecular weight if your unknown sample contained a insoluble impurity of lower molecular weigh than the pure sample? Explain.
2. During heating, some solution of NaCl spattered out of the evaporating dish. How would this affect the percent recovery of the mixture?
1. While performing the Dumas experiment, if the outside of the flask were not completely dry (Part I), how would this affect the calculated molar mass of the unknown volatile liquid? Would it be higher or lower? Explain.
Why should the recrystallization mixture be cooled in an ice bath prior to filtering?
In glucose estimation using Benedict's Reagent, justify the necessity of continuously heating the solution while it is titrated with Benedict's reagent.
In this lab, you used rotary evaporation to remove the neutral organic solvent. Rotary evaporation is an example of a distillation except under conditions of a reduced pressure atmosphere. What effect does a reduction in atmospheric pressure have on the observed boiling point? Explain your answer.
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Show your calculation for the preparation of 100 mL of a solution of approximately 4 mM (that is 4 x 10-3 M) o-nitrophenol (M.W. 139.11 g mol-1) using 0.40 M Na2CO3 as the solvent.
A student forgot to add the mass of the unknown solute in trial 1 to the mass of the solute that was weighed for trial 2 and then added to the cyclohexane-solute solution used in trial 1. How would this omission affect the calculated molecular weight of the solute?
Complete the following table of reagents – think carefully about the stoichiometry. You will need to write these down to carry out the experiment. For each gram of benzil starting material. Molecular Mass Reagent Volume (mL) density Equivalents Amount required (g/mL) weight (g) (mmol) (g/mol) benzil 210.23 4.75 1.00 1.00 urea 60.06 0.432 1.75 7.19 Sodium hydroxide (30% w/v solution) 39,847 4 1.2 4.0 loo What volume of ethanol is required, per gram of benzil, to generate a solution with a concentration of 0.33M? Show your working.