Can someone please help me with this lab. I am so confused as to how to solve for some of these things. Also I'm not sure at all how to answer the "thought" questions. If someone could please help me with these I would greatly appreciate it.

OLECULAR WEIGHT DETERMINATION BY FREEZING POINT DEPRESSION EXPERIMENT A DATA Determination A. Freezing point of solvent B. M.W. of known solute ã¼ (9.60 Weight of known solute Weight of solvent Freezing point of solution Freezing point depression (AT) Molality of solute (m) alok- alse akase tort-bteed C. Unknown number Weight of unknown solute Weight of solvent Freezing point of solution Freezing point depression (aT)_ Molality of solute (-AT/K) MW. of unknown 98 show calculation: D. Accepted M.W. (if known) Percent error saciic ontl

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Please help me solve for the molar mass of sample 1 and 2 and the molecular formula

Experiment 1084-03: Determination of M.M. by Freezing Point Depres sion Measure the freezing-point depressions solute whose empirical formula is known Pool the class hat occur with solutions containing mass of the solute and its Background Information However, as soon as the solution begins to freeze, Adding a solute to a pure, non-volatile lquid ature will remain constant untl all the (solvent) lowers the vapor pressure of the solvent raises its boiling point, and lowers (depresses) its freezing point. The extent to which these are aftected depends on the relative number of solute particlos in the solution. Properties of solutions that depend only on the number of solute molecules in a given quantity of solvent are called colligative properties. Such cyclohexane turns into solid. Once the substance again. The freezing point is the temperature where it stays constant, Le. the liquld phase and the sold phase of the cyclohexane coexists (Figure 3-1) boiling point elevation and osmotic pressure. They do NOT dopend on the nature of the solute, but DO depend on the nature of the solvent. As a consequence, colligative properties can be used to determine an unknown molar mass for a solute. In this experiment, we will be using cyclohexane (d " 0.779 gmL, K, . 20.5 oC/m) as the solvent to determine the molar mass of a white solid with an empirical formula of C,HC. The freezing point depression, Î7, is the difference between the freezing point of the pure solvent, TP, and the freezing point of the solution (solvent and solute). T As mentioned above, thits quantity is proportional only to the molal concentration of the solute, m Figure 3-1. Cooling Curves The proportionality constant, K, is called the freezing-point-depression constant. The K value of 20.5 C/m for Cyclohexane is one of the largest values one can find. Molal concentration is defined as the number of moles of substance in 1 kg of solvent. Now we can calculate the molar mass of a solute from ATã K,, the mass of the The freezing point of a solution in cyclohexane can be obtained in a similar way. Cooling results in an initial rapid decrease in the temperature until freezing begins as seen in the cooling curve of the pure solvent. However, the temperature of the solution does not remain constant while being frozen. As the cyclohexane in the solution treezes, cyclohexane is taken away from the solution and the concentration of the solute becomes higher In the liquid portion. Thus the molal concentration of the solute increases and the freezing point of the solute and the mass of the solvent. remaining liquid becomes lower. The result is a steadily decreasing freezing temperature until the solution is completely frozen. When all the solution In order to determine ATP, we will measure the freezing point of pure cyclohexane and the freezing point of a solution of the solute in is frozen, the temperature decreases more rapidly To evaluate the freezing point of pure cyclohexame, you will cool a sample of this substance, and measure the temperature as a The freezing point of the solution is the temperature at which the solution starts to freeze. portion represents the concentration of the starting function of time. As cooling begins, theOnly at this point, the concentration of the liquid temperature of the cyclohexane decreases rapidly.

A student determines the freezing point of a solution of 2.07 g ofnaphthalene in 27.00 g of paradichlorobenzene. they gave a set oftemp-time readings and I had to graph them. the time readings wereto 1.0 minutes and the temp readings were also to 1.0 C.

Then I found the Freezing point of the solution to be 49.1 C.

a.) what is the freezing point depression, Delta T, given that thefreezing point for pure paradichlorbenzene is 53.0 C?

I got 3.9 C by subtracting 53-49.1

b.) using Kf = 7.10 C/m(C kg/mole) for Paradichlorobenzene and m =delta T / Kf, calculate the molarity of the naphthalene.

I got .55 m

c.) using MM= Kf(number grams solute)/((number kg solvent)(deltaT)) calculate the MM of naphthalene

I got ~ 140 g/mol

d.) if part c consistent with the real molar mass of 128 g/mol?

e.)calculate the percent error that is introduced in the calculatedmolecular weight, if a 1.0 C error exists in the determination ofthe delta T? be very specific. show the calculation for 1.0 Chigher and 1.0 C lower.

I got 9.4 % ( (140-128)/128 x 100 = 9.4 %)

if + 1.0C i got 13.2 %

if - 1.0 C i got 46.6 %

f.) how accurately must we determine delta T in order to be assuredof an accurate value for the molecular weight? be very specific bysupplying a numerical value. explain your rational.

g.) what changes or refinements in the experimental procedure doyou recommend to attain the desired accuracy in delta T? be veryspecific,

I AM SO SORRY THIS IS SO LONG! PLEASE COMFIRM THAT I HAVE BEENDOING THIS RIGHT. IF I AM NOT, PLEASE SHOW STEPS. I REALLY JUSTNEED HELP ON F AND G, BUT I PUT THE REST THERE SO YOU CAN SEE MYANSWERES. THANK YOU SO MUCH!!!!! :)