May I get help. Just want to verify my answers to number 7 and 8. Also help with
ID: 1084320 • Letter: M
Question
May I get help. Just want to verify my answers to number 7 and 8. Also help with 9 and 10. Other photos are for reference. The Kfp to use is 5.0 not 6.9C.
REPORT SHEET EXPERIMENT Colligative Properties: 19 Freezing-Point Depression and Molar Mass 30.662 g 1. Mass of test tube 1. Mass of test tube +sulfur 2. Mass of sulfur 3. Mass of test tube+ sulfur + naphthalene4.987 g 4. Mass of naphthalene 32.144 g 1.482 17.843 ooling-curve data naphthalene A Naphthalene tsulfurB Tem Pure Part B cont. Time Time 0.00s 8.9 C 87.5 C 84.8 C 82.1 C 6.3 C 90.1 c .00s 76.0 C 360.0s 30.0 s 60.0 s 90.0 s 120.0 S 150.0s 60.0 90.0 87.5 C 85.1 C 76.0 C 390.0s 82.8 C 81.0C 79.8C 180.0 210.0 s 240.0 S 270.0 80.8 120.0 150.0 180.0 210.0 240.0 79.5 c 78.5 C 78.0 C 77.3 C 79.2 C - 91 77.0 C 270.0 300.0s 79.1 C 79.0 C 76.7 C 76.1 C 300.0 7. Preezing point of Pure naphthalene, from cooling curve .479 c 8. Freezing point of solution of sulfur 9. Molality of sulfur or unknown (show calculations) in naphthalene-76c &T;
Explanation / Answer
Depression in freezing point
From the data above
7 and 8 the freezing point of pure solvent and that of the solution is correct.
9. molality = dTf/Kf
with,
dTf = 79 - 76 = 3 oC
Given,
Kf = 5.0 oC/m
so we get,
molality of sulfur = 3/5
= 0.6 m
10. is missing from the chart above