Question

The freezing point depression of a solution made b
0 0
Add a comment Improve this question Transcribed image text
Answer #1

i) depression in freezing point ΔTf = 7.19 oC - (-0.98 oC) = 8.17 oC

ii)      mass of solute = volume x density = 5 ml x 6.18 g/ml = 30.9 g

   molar mass of unknown, M = ?

   mass of solvent in Kg , W = 0.5 kg

molality = (w/M) x (1/W in kg)

                    =  (30.9 g/M) x (1/0.5 kg)        

   = (30.9 /M) x (1/0.5) m

iii)       ΔTf = kf x molality

8.17 oC = 9.8 oC m-1 x (30.9 /M) x (1/0.5) m

M = 74.1 g/mol

Hence,

Molar mass of unknown = 74.1 g/mol

Add a comment
Know the answer?
Add Answer to:
The freezing point depression of a solution made by the addition of a nonionic unknown solute...
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions
  • What is the unknown solute in a solution of benzophenone with using freezing point depression? In...

    What is the unknown solute in a solution of benzophenone with using freezing point depression? In this lab, the test tube with the solution was put in a hot water bath on a hot plate. The test tube was in a beaker. Mass of benzophenone: 6.863 g Mass unknown: 0.752 g I placed benzophenone in a test tube in the hot water bath. Once it melted, I recorded 48.5 C. I stirred the test tube and the temperature lowered to...

  • Need help with freezing point depression expeiment volume of acetic acid 30 volume of unknown solute...

    Need help with freezing point depression expeiment volume of acetic acid 30 volume of unknown solute in solution1    1.5 volume of unknown solute in solution 2 1.5 freezing point of pure acetic acid 16.3 freezing point of solution 1 14.5 freezing point of solution 2 11.3 average molar mass of unknown solute Calculations for Part 1 The density of acetic acid is 1.049 g/mL and Kf(acetic acid) =3.90 °C·kg/mol The density of the unknown is 0.791 g/mL. 1.Calculate the masses...

  • Molar Mass Determination by Freezing Point Depression Calculate and enter the freezing point depression of a...

    Molar Mass Determination by Freezing Point Depression Calculate and enter the freezing point depression of a solution of 57.6 g ethylene glycol (C2H602) in 734 g H20. Kffor H20 is 1.86 °C kg/mol. °C -2.53 1 homework pts Submit Answer Incorrect. Tries 3/5 Previous Tries A solution which contains 71.9 g of an unknown molecular compound in 363 g of water freezes at -3.85°C. What is the molar mass of the unknown? g/mol 1homework pts Submit Answer Tries 0/5 Molar...

  • Date Name Lab Section Partner(s) Determination of Molar Mass by Freezing Point Depression Data: Mass of...

    Date Name Lab Section Partner(s) Determination of Molar Mass by Freezing Point Depression Data: Mass of empty test tube 2.2.6! Mass of test tube plus approximately 10.0 g of benzophenone 33.39 The difference is the mass of benzophenone (solvent) 8 kg Mass of unknown (-1.0 g) 1:09: 48.50°c 42.08. Freezing point of pure benzophenone Freezing point of benzophenone containing the unknown The difference is A fp CO Calculations: (Show set-up with cancellation of units) 1. molality of solution 2. moles...

  • for question 1 the molar mass of unknown is 102g/mol hation by Freezing Point Depression Vernier...

    for question 1 the molar mass of unknown is 102g/mol hation by Freezing Point Depression Vernier Logger Pro for Windows Section Post-Laboratory Questions (Use the space provided and additional paper if necessary. Record your nemerical answers in the boxes provided.) 1. Obtain the correct molar mass of your unknown from your laboratory instructor. Calculate the percent error in the molar mass that you found. Torg/mol percent error, 2. A student determined the freezing point of pure t-butyl alcohol following the...

  • Calculate the freezing point and boiling point of a solution containing 20.0 g of naphthalene (C_10H_8)...

    Calculate the freezing point and boiling point of a solution containing 20.0 g of naphthalene (C_10H_8) in 119.0 mL of benzene. Benzene has a density of 0877 g/cm^3. Calculate the freezing point of a solution (K_f (benzene) = 5.12 degree C/m) T_f = 2.54 Calculate the boiling point of a solution. (K_b (benzene) = 2.53 degree C/m) T_b =

  • Post-Lab Material Experiment 19 Data and Calculations: Molar Mass Determination by Depression of the Freezing Point...

    Post-Lab Material Experiment 19 Data and Calculations: Molar Mass Determination by Depression of the Freezing Point 0.3 Name Section A. Measured Freezing Point of Pure Water B. Finding the Freezing Point of a Solution of Liquid Unknown Target mass of solute (Calculated based on the parameters in the instructions) Unknown # Liquid 3.5 Actual mass of solute used Trial Freezing point of solution (observed) -3.0 Mass of solution 116.6 Trial II Freezing point of solution -3.3 Mass of solution 101.3....

  • I'm having trouble determining how to find delta T and the freezing point depression for Solutions...

    I'm having trouble determining how to find delta T and the freezing point depression for Solutions #1 and #2. This is all the information I have. Please show all work. Thank you. Mass of test tube 24.7795 g Mass of tube + BZP 34.2490 g Mass of BZP used 9.4695 g Freezing point of pure BZP -9.80 kg/mL Solution 1 Solution 2 Mass of container and Sample 11.7366 g 11.7366 g Mass of container and Sample (after weighing) 11.0103 g...

  • Freezing point depression can be used to experimentally determine the van't Hoff factor of a solute...

    Freezing point depression can be used to experimentally determine the van't Hoff factor of a solute in solution. Given the data in the table, please answer the questions below and determine the "real" van't Hoff factor of the solute. Experimental Results Mass of solvent (water) Freezing point of water Freezing point depression constant (Kf) of water Mass of solution Freezing point of solution 8.515 g 0.00°C 1.86°C/m 9.3589 -5.45°C a. What mass of solute was used? b. What is the...

  • Molar mass determination by depression of freezing point lab I'm stuck on calculating the moles of...

    Molar mass determination by depression of freezing point lab I'm stuck on calculating the moles of solute.. How do I calculate it? Also can u please check if I've done everything else correctly.. The data I collected: Measured freezing point of pure water: 0.0 degrees Celsius Actual mass of solute used: 10.12g Freezing point of solution (observed): -3.4 Celsius Mass of solution: 84.7g Freezing point of a Solution of liqud unknown Freezing point depression: Trial #1. 0.0℃ (-3.4°C)= 3.4℃ Molality...

ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT