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2025-2026 (CHEM 103) LAB REPORT 8 | PORTAGE LEARNING| GRADED A+, Exams of Chemistry

2025-2026 (CHEM 103) LAB REPORT 8 | PORTAGE LEARNING| GRADED A+

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2024/2025

Available from 05/08/2025

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2025-2026 (CHEM 103) LAB REPORT 8 | PORTAGE
LEARNING| GRADED A+
Chemistry Lab
Report
Experiment # 8
Title: Molecular Mass
Purpose: In this lab we will determine the molar mass of an unknown solute by its
fressinhg point depression.
Procedure:
1. Measure out 10 ml of cyclohexane (the solvent). We will get the molar mass of the
(Solute) of the unknown substance. Pour the cyclohexane into the testtube and fit it
with a stopper. The stopper has a hole for the wire (stirrer) and thermometer.
2. Insert testube into ice (mixture of ice and salt). Create a cold bath and let the
cyclohexane cool down and let the bottom freeze. Wait till there are a nice number of
crystals on the ottom part that are frozen really well.
3. Clamp testube . The initial temperature is 6.6C , read and record temperature every 30
seconds and create a warming plot to see freezing point. 30 seconds-6.6c 120 seconds-
7 C 8 minutes
11.4 C
.
4. Started at 6.6 C fully frozen and leveled off at 6.6 and stayed there after 2 minutes it
started to warm. Now add the unknown solute to cyclohexane which will depress the
dressing point. Weigh out some of the solute at .3014 grams of unknown solute.
5. Swirl around to see flakes floating around. In order for it to be a solute it needs to be
dissolved. Add 10 mo of original solvent (cyclokexane) and stirl until all crystals
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2025 - 2026 (CHEM 103) LAB REPORT 8 | PORTAGE

LEARNING| GRADED A+

Chemistry Lab Report Experiment # 8 Title: Molecular Mass Purpose: In this lab we will determine the molar mass of an unknown solute by its fressinhg point depression.

Procedure:

  1. Measure out 10 ml of cyclohexane (the solvent). We will get the molar mass of the (Solute) of the unknown substance. Pour the cyclohexane into the testtube and fit it with a stopper. The stopper has a hole for the wire (stirrer) and thermometer.
  2. Insert testube into ice (mixture of ice and salt). Create a cold bath and let the cyclohexane cool down and let the bottom freeze. Wait till there are a nice number of crystals on the ottom part that are frozen really well.
  3. Clamp testube. The initial temperature is 6.6C , read and record temperature every 30 seconds and create a warming plot to see freezing point. 30 seconds-6.6c 120 seconds- 7 C 8 minutes 11.4 C .
  4. Started at 6.6 C fully frozen and leveled off at 6.6 and stayed there after 2 minutes it started to warm. Now add the unknown solute to cyclohexane which will depress the dressing point. Weigh out some of the solute at .3014 grams of unknown solute.
  5. Swirl around to see flakes floating around. In order for it to be a solute it needs to be dissolved. Add 10 mo of original solvent (cyclokexane) and stirl until all crystals

dissolved.

  1. Now reinsertthe stopper fitted for the thermometer and stirrer and stick back into the ice bath to cool. The cyclohexane is now close to room temperature of 22C, let it cool with an ice bath. Because solid freezes over and super cool, once it is solid we can stick it again back on the ring stand and watch the eating curve. Now it is down to about 8 C. The solute added should depress the freezing point and there will be a difference of 5 - 6 C of depression. Now abou 5 C, after stirring it continued to go down to 2 C, then 1.4 C.
  2. Record Time 0: 1.4 C (pure cyclohexane was 6.6 C a time ).Continue recording 30 seconds: 8C, 1 minutes 8C, 8 minutes- all solid melted. Data/Results/Calculations: Compared to pure cyclohexane it was 6.8 C, 5.8 C difference in depression and we can see the warming curve. Calculations for Molar Mass” Working with 10 ml of cyclohexane with density of 0. g/ml Convert mass for locality in kilograms .0773 kg mass Delta T=kfm* 5.8C=20. c/m*m M=0.2843 mol Mol= ( mol solute/kg

bath and the temperatures recorded every 30 seconds. The freezing point of the mixture had a total depression of 5-6C, compared to the freezing point of the pure cyclohexane. The conclusion is that the molar mass of the unknown solute was successfully determined using the freezing point depression method. Notes: Colligative properties result because of the amount of a substance that is in a solvent. Colligative properties result because of the number of particles and not their identity Remember all articles regardless of their identity will impact a solvent the samw way