Colligative Properties

Notes:

GMM of Camphor is 125 g.

There is a problem that looks like this in your packet.
If 2.5 g of solid Fe(NO3)3 is added to 100 mL of a 1 ×10−20 M NaOH solution, will a precipitate form?
1. Fe(NO3)3 does not precipitate.
2. Fe(NO3)3 precipitates.

The choices should say:
1. The insoluble product precipitates
2. The insoluble product does not precipitate.

Pure Acetic Acid Freezing point is 16.6 oC

If you have a problem that has Kelvin in the units of the constant, don't panic. Since a Celcius degree and and Kelvin degree move the fluid in a thermometer the same distance a change of one degree Celcius = a change of one degree Kelvin.

Videos;

Go to the desktop on the computers or your flash drive and watch these videos in the AP Chemistry folder.
VP of solutions
BP elevation
FP depression
11.2

Solutions6.mp4

Labs:



(optional) If you do this one you must answer the questions and turn them in.

Use the simulated Lab below for this lab 4.
Simulation: When the simulation tries to open, allow blocked content.
More Complex (Use the simulated Lab below for this lab 4.)

Simulated Lab:

Discussion

Pay attention to Page 438-441 in your book.
The main formula is ΔT = k m. The “m” stands for molality usually moles of chemical per kg of solvent. BUT in this chapter the “m” stands for moles of ions/kg of solvent. For example one mole of AlCl3 produces 4 moles of ions. AlCl3 ® Al+3 + 3 Cl-1. A nonelectrolyte will produce one mole of ions from one mole of molecules. Example C12H22O11 à C12H22O11
So if a 1 m (molal) solution of aluminum chloride would change the freezing point 4 times more than you expected. Watch for “What the Question Asks”. If it says what is the new freezing point, you subtract the normal freezing point from the normal freezing point. If it says what is the new boiling point, you add the normal boiling point from the normal freezing point.
Lastly, pay attention to which chemical is the solvent. You will use water so much you will tend to forget that other chemicals can serve as the solvent and have different boiling/freezing points.
DeannaElizabeth Oct 30, 2009 8:45 am
When working with colligative properties students need to understand how to balance equations properly. They also need to understand how to get the molality of a solution. Also, be careful and make sure you use the proper constant for either boiling points or freezing points of solutions. Remember you must subtract the pure substances boiling or freezing point from the freezing or boiling point depression to get the freezing or boiling point for the solution being used. Be sure to refer to the chart and examples on pages 438 - 441 in your Modern Chemistry book. Deanna B.
MarleeDW Feb 1, 2010 7:20 am
*Table 14-2 on Page 438 answers lots of questions you may have. *Formulas you will need can also be found on Page 438 and 439. *When solutes are nonelectrolytic, they DO NOT break apart. *Carbon Compounds are nonelectrolytic and DO NOT break apart. *When solutes are electrolytic, you must change moles to moles of ions. If you don't then you will miss the problem. *The examples on Page 439 and 440 will save your life and basically show you how to work every problem. Have Fun, It's not too hard :) Marlee Williams
nchskayleighm Feb 2, 2010 8:22 am
-Use the chart on page 438 to help you with the freezing and boiling point. -The example problems on pages 439-441 will help out a lot. -nonelectrolytes DO NOT break apart -you will need to change moles to moles of ions in some problems in order to get them correct. -molality=mol/kg -when looking for grams, pay attention to what you're given. you need to be able to convert temperature to moles and moles to grams. Good Luck Kayleigh McCool
srf577 Feb 2, 2010 9:01 am
Read the questions carefully. Read section 3 in the Chemistry book to understand what is delta "T" is. Read about boiling-point elevation and freezing-point elevation. Examples for mol of ions, degrees Celsius, and molality are in the book on pages 439 and 441. Remember to ask questions if you don't understand what the question is asking you to do. The problems are not very hard. So, it should be easy to work and solve. Good Luck! Shunda Fox
bss601 Feb 2, 2010 9:11 am
Be sure to bring your book everyday this packet was difficult for me. Be sure you know if a solution is nonelectrolytic do not break apart. If solutes you must change mol to mol ion. You need to understand boiling point and freezing point and read problem carefully and see what’s its asking. GOOD LUCK BRITANY SHUCK
MarleeDW Feb 19, 2010 8:38 am
Colligative Properties Labs: -For the Sugar Content in Soft Drinks lab, the drinks can be found in her closet under the sink. It calls for four drinks but only three were available. You calculate the percent sugar from your excel graph. Make sure you use the graph to the right on Page 5 to answer questions three through seven on Page 5. It would help in solving them correctly. -On the Boiling Point Elevation Lab, it says for Partner 2 to use Calcium phosphate, but BOTH PARTNERS ARE TO USE NACL. -On the Ice Cream Lab, get milk and ice form the cafe and make sure you take your time eating the ice cream because it doesn't go very far between two people. -The antifreeze for the Antifreeze Labs can be found on the first shelf on the bottom on the back wall of chemicals. On the second lab it asks for the Calculated Specific Gravity. To solve for it, divide your density of each solution by your 0% solution. -These labs are easy-peasy. Have faith in yourself. You will do GREAT. Marlee Williams
mk_2493 Feb 19, 2010 9:21 am
The questions are pretty simple just use the solubility rules if it is insoluble it does not break apart and is a non-electrolyte. Remember to use mole of ions for the non-electrolyte. The molal freezing point and boiling point constants are in the textbook. also if you are finding the molal-freezing point constant for a specific compound just remember that to get the freezing point you add the constant to the freezing point depression. Good Luck everything you need is in the textbook. *Mahreen Khan
bss601 Feb 19, 2010 9:27 am
COLLIGATIVE PROOERTIES LABS -When doing the Freezing Point of Ice cream Lab don’t add too much milk and the lab requires more ice then the packet tells you. -The Antifreeze Labs make sure the percentages are right. Measure out the correct percentages. Each partner should do a different brand to save time. -The Boiling Point Lab be sure to convert everything right. Be sure to let solutions BOIL before taking temperature. When ready to take temperature hold thermometer up enough so it’s not touching the bottom of beaker, this is important. -The Sugar Content of Soft Drinks Lab be sure to measure the hydrometer correctly. Must be measured from top of liquid NOT from top of cylinder. Also be careful when measuring the water out. BRITANY SHUCK
srf577 Feb 22, 2010 8:57 am
Sugar Content of Soft Drinks Lab requires precise measurements. So take your time. Antifreeze Labs are easy to do just ask questions on a couple. Boiling Point Lab is simple. Have a stop watch to time 3 minutes precisely. Don’t let the thermometer touch the bottom to get the right temperature. The Freezing Point of Ice cream Lad does not require a bathroom cup full just a half way to the top. Knead the mixture together for about 5 to 6 minutes. Good luck! Shunda Fox
CSpears Feb 18, 2010 7:34 am
This chapter is very easy. Use your book on each problem. Page 438 will be very useful. The chart on this page has all the constants you need. Also, make sure you do the NET IONIC EQUATIONS. DO NOT FORGET THIS!! Read each problem carefully to make sure you get the correct work to complete the question it ask. The most used equation is the change in t=KM. K is the constant given on page 438 and M is molality. Ask questions when you get stuck. Do not over think the problems. They are very simple. Good Luck. CSpears
DeannaElizabeth Nov 19, 2009 8:01 am
- When working on the Sugar Content of Soft Drinks Lab be sure to fill the hydrometer with the correct amount of water and be careful when measuring the height of the hydrometer. - When working on the Freezing Point of Ice cream Lab make sure not to add too much milk and add plenty of ice, the lab will require more than the lab tells you, to reach the freezing point for the ice cream. - When working on the Antifreeze Labs be sure to use a graduated cylinder to measure the amounts of water and antifreeze that you need to use, so that the measurements are accurate. When measuring the specific gravity you will probably have to estimate. - When working on the Boiling Point Elevation Lab be sure to convert your moles to grams properly and get as close as you can to the correct amount of salt that you need to add to the solution. Be sure to let all the solutions boil before taking the temperature and remember to not let the thermometer touch the bottom of the beaker when trying to find the boiling point. Deanna Burt
KatelynCheatham Dec 10, 2009 10:02 am
When working with colligative properties be sure to read the question thoroughly and understand what is being asked. If dealing with a nonelectrolyte, the moles given are used. In electrolytic solutions, the moles of ions are used. The handout sheet with the solubility rules on it is needed to work some of the problems. When looking for a fraction answer, begin with a fraction in the stoicheometry. (Ex: m is the symbol for molality. Molality is mol/kg. Begin stoichiometry with the mol of the problem and cancel each unit.) When looking for a nonfraction answer, begin with a nonfraction answer. Most of all, remember to ask questions early. Shamiski Collier
HaleyElizabeth3 Nov 19, 2009 8:00 am
Colligative Properties -On the Sugar Content of Soft Drinks Lab, be sure to carefully measure the length of the hydrometer so that you won't have any errors in measurements. -On the Ice Cream Lab make sure you don't add an excess of any ingredient, or the ice cream won't properly become a solid. -On the Antifreeze Lab part 1, one partner should do one brand while the other partner does the other brand so that you save on time. -Be extra careful on the Boiling Point Elevation Lab to correctly add the required amount of NaCl. Too little or too much will interfere with your boiling point. Haley Pierce
HaleyElizabeth3 Nov 2, 2009 7:56 am
While working with colligative properties students need to pay careful attention to page 438 in their Chemistry book to work the problems. The formulas on page 438 and 441 are also important. Students should make sure they read the problem completely and careful to make sure they do not confuse things such as boiling-point elevation and boiling point, or freezing point and freezing-point depression. Haley P.