Lab: Molar Mass by Freezing Point Depression Colligative properties can be used to determine the molar mass of a compound by relating the decrease in freezing point (or increase in boiling point) to...

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Lab: Molar Mass by Freezing Point Depression
Colligative properties can be used to determine the molar mass of a compound by relating the decrease in freezing point (or increase in boiling point) to the particle molality of a solution. In this lab, you will measure the freezing point of a pure solvent (lauric acid). Then you will measure the freezing point of a solution using the same solvent and a solute (lauric acid with benzoic acid). The amount the freezing point is lowered from the pure solvent will allow you to determine the molality and ultimately the molar mass of the benzoic acid solute.


View the Molar Mass by Freezing Point Depression power point attached below.This will provide you with the necessary foundation for safely and successfully completing the lab.



Note:While you work on the lab,you are required to take certain images/photos of your labto document that you actually completed the lab yourself. Each photo should include anote card or a piece of paper with your name, the date you completed the experiment and your course section numberclearly visible.


Note Card Information:


My Name: Zack Aldawoody


Section Number:145454
Download the item:Molar Mass by Freezing Point Depression Lab Report attached below. This is what you will submit for grading. You can type your results and insert your images into this document.



Introduction to Graphing Molar Mass by Freezing Point Depression Lab CHEMISTRY 111 Overview •Measure the freezing point of both a pure solvent and a mixture of the solvent and solute. •Determine the molality of a solution and moles of solute •Determine molar mass from freezing point depression data •Determine percent error •Review precision and accuracy Materials Needed Printed materials and needed from the kit: ◦ Printed Investigation Manual ◦ Printed lab report ◦ Safety goggles • Gloves • Apron • Grease Pencil or marker • Test tube rack • 250-mL beaker • 2 Weighing boats • Thermometer • Electronic Balance • 2 Plastic Spoons Materials Needed Needed from the kit: ◦ Lauric Acid ◦ Benzoic Acid ◦ 4 Glass test tubes Materials Needed Needed but not supplied with the kit: ◦ Tap water ◦ Paper towels to clean the thermometer ◦ Stove or microwave ◦ Pot, saucepan, or microwavable container large enough to hold 300 mL (10 oz) of water (easy to pour) ◦ Oven mitt or pot holder ◦ Timer, stopwatch, or cell phone stopwatch Prior to the Lab •Carefully review the entire Investigation Manual, including the Overview and Objectives, Background information, necessary materials, safety precautions, lab preparation and procedures for all activities, and the waste disposal and clean-up information. •Make sure your work area is clean and out of the reach of pets and children. •Put your PPE, including the safety goggles, on and be sure to leave them on for the entire experimental procedure. Special Safety Precautions •Lauric acid and benzoic acid can cause eye irritation or damage. •Benzoic acid can cause respiratory irritation. •Do not microwave the thermometer. •Do not pour either acid down the drain in a sink, as it may result in clogging of the drain. • Dispose as directed on both Page 5 and 7 of the Investigation Manual. Activity 1 – Lab Tips •Be sure to record all mass readings to two places after the decimal point. •Take all temperature readings to 1 place after the decimal point. •Dry the thermometer with paper towel before placing it in the test tube with the lauric acid. •The lauric acid will be heated above 70oC after it is melted. •Remove test tube from hot water and begin timing and recording temperatures once the temp is at 65.0oC. (Step 11) •You may not need the full 10 minutes to reach 4 steady temperature readings. •Be sure to completely clean the thermometer when you remove it from the frozen lauric acid (see Page 7, Step 15). For example, this thermometer would be read as 31.6oC. Activity 2 –Lab Tips •Make sure you do not cross contaminate. • Use separate dedicated spoons and weighing boats for lauric acid and benzoic acid. Label them! •Remember to record the exact mass for each (mass of lauric acid AND mass of benzoic acid) to 2 places after the decimal point. •Be sure to continue to stir and heat until all the benzoic acid has dissolved after the lauric acid has melted. Images/Photos As you complete this lab, please capture images of the following steps of the lab procedure to include in your submitted lab report. • Image 1:Photo of the crystallized lauric acid for Activity 1 (See Page 7, Step 13) • Image 2:Photo of the weighing of 0.4 g benzoic acid with balance read-out visible for Activity 2 (See Page 7, Step 3) • Image 3:Photo of the weighing of 0.5 g benzoic acid with balance read-out visible for Activity 2 (See Page 7, Step 7) • Image 4:On a separate piece of paper, write out the calculations showing ALL WORK AND UNITS for Calculations 1-6 for one of the benzoic acid trials (See page 9) For each image you capture, include a card with your name, the appropriate date and section number written on it. This card must be visible in each image you submit with your lab report. Failure to include these images or the card with the image will result in a grade of zero for the submitted lab. Clean Up •Dispose of the weighing boats, spoons and test tubes as directed in the Disposal and Cleanup section of the Investigation Manual (see page 7). •Place your equipment and supplies back into their safe storage location until you need them again. •Clean and disinfect all surfaces used. •Thoroughly wash your hands. Molar Mass Determination by Freezing Point Depression Activity 1: Freezing Point of Pure Lauric Acid & Activity 2: Freezing Point of a Lauric Acid/Benzoic Acid Mixture Data Table 1 (2 points) Complete the information below based on Data Table 1: Cooling Data for Activities 1 and 2 from the Investigation Manual. Note: You may not need to enter temperatures for every time shown. Time (mm:ss) Pure Lauric Acid Lauric Acid + 0.4g Benzoic Acid Lauric Acid + 0.5 g Benzoic Acid Temperature in ° C Temperature in ° C Temperature in ° C 0:00 65.0 65.0 65.0 0:30 00.000.000.0 1:00 00.000.000.0 1:30 00.000.000.0 2:00 00.000.000.0 2:30 00.000.000.0 3:00 00.000.000.0 3:30 00.000.000.0 4:00 00.000.0 00.0 4:30 00.000.000.0 5:00 00.000.000.0 5:30 00.000.000.0 6:00 00.000.000.0 6:30 00.000.000.0 7:00 00.000.000.0 7:30 00.000.000.0 8:00 00.000.000.0 8:30 00.000.0 00.0 9:00 00.000.000.0 9:30 00.000.000.0 10:00 00.000.000.0 Data Table 2 (3 points) Complete the information below based on Data Table 2: Molar Mass of Benzoic Acid Data in the Investigation Manual. Molar Mass of Benzoic Acid Pure Lauric Acid Lauric Acid + 0.4 g Benzoic Acid Lauric Acid + 0.5 g Benzoic Acid Mass of Lauric Acid (g) 0.000.000.00 Mass of Benzoic Acid (g) 0.000.000.00 Freezing Point (o C) (From Analysis of Data Table 1) 00.000.000.0 Freezing Point Depression (o C) 0.00.0 Molality of Benzoic Acid in Lauric Acid 0.000.00 Moles of Benzoic Acid 0.00 x10 00 0.00 x10 00 Experimental Molar Mass of Benzoic Acid 000000 Average Molar Mass 000 Percent Error 00.0 Post-Lab Questions (3 points, 0.5 pts each) 1. Using the accepted molar mass for benzoic acid to determine the molality of 0.95 g of benzoic acid dissolved in 60.0 g of lauric acid. Determine the freezing point depression. Click or tap here to enter calculated molality. 2. Determine the freezing point depression for the solution in the previous problem. See page 9 of your Investigation Manual for the freezing point depression constant for lauric acid. Click or tap here to enter freezing point depression in deg C. 3. How would you rate the precision of your results? (Compare the values determined for experimental molar mass of benzoic acid.) Click or tap here to enter text. 4. How would you rate the accuracy of your results? Explain what data you are comparing in your response. Click or tap here to enter text. 5. Rank the relative freezing point depressing ability (ΔTf) of 0.10 m aqueous solutions of KBr, CaBr2 and C12H22O11. (List left to right from largest ΔTf to smallest ΔTf.) Click or tap here to enter text. 6. Explain the reasoning for your ranking in the previous problem. Click or tap here to enter text. Images (2 points) A required part of this laboratory experiment is to capture pictures of the experimental process and results. Click on the icon in each of the boxes below to include the required images for this lab. Remember to include a card with your name, the correct date and the section number in each image. Note: Failure to submit these images as required will result in a grade of zero for this lab. Review the Inserting Images into a Worksheet tutorial for further instructions. Photo of the crystallized lauric acid for Activity 1 (See Step 13). Photo of the weighing of 0.4 g benzoic acid with balance read-out visible for Activity 2 (See Step 3). Photo of the weighing of 0.5 g benzoic acid with balance read-out visible for Activity 2 (See Step 7). On a separate piece of paper, write out the calculations showing ALL WORK AND UNITS for Calculations 1-6 for one of the benzoic acid trials (See Activity 2, Page 9).
Answered 2 days AfterNov 11, 2021

Answer To: Lab: Molar Mass by Freezing Point Depression Colligative properties can be used to determine the...

Neelakshi answered on Nov 14 2021
117 Votes
Molar Mass Determination by
Freezing Point Depression
Activity 1: Freezing Point of Pure Lauric Acid & Activity
2:
Freezing Point of a Lauric Acid/Benzoic Acid Mixture
Data Table 1
(2 points) Complete the information below based on Data Table 1: Cooling Data
for Activities 1 and 2 from the Investigation Manual. Note: You may not need to
enter temperatures for every time shown.
Time
(mm:ss)
Pure Lauric Acid
Lauric Acid + 0.4g
Benzoic Acid
Lauric Acid + 0.5 g
Benzoic Acid
Temperature in ° C Temperature in ° C Temperature in ° C
0:00 65.0 65.0 65.0
0:30 66 66 66
1:00 67 67 67
1:30 68 68 68
2:00 69 69 69
2:30 70 70 70
3:00 71 71 71
3:30 72 72 72
4:00 73 73 73
4:30 74 74 74
5:00 75 75 75
5:30 76 76 76
6:00 78 78 78
6:30 79 79 79
7:00 80 80 80
7:30 81 81 81
8:00 82 82 82
8:30 83 83 83
9:00 84 84 84
9:30 85 85 85
10:00 86 86 86
Data Table 2
(3 points) Complete the information below based on Data Table 2: Molar Mass of
Benzoic Acid Data in the Investigation Manual.
Molar Mass of
Benzoic Acid
Pure Lauric Acid
Lauric Acid + 0.4
g Benzoic Acid
Lauric Acid +...
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