Colligative Properties

Today in chemistry we kicked off class with a lecture regarding colligative properties. There are 4 types of colligative properties and they are:
1.Vapor Pressure Lowering
2. Boiling Point Elevation
3. Melting Point Depression
4. Osmotic Pressure
Basically, the relations are simple. The more solute added, the more the vapor pressure decreases. The more solute added, the more the boiling point raises. The more solute added, the lower the melting point becomes. We also got a few formulas to accompany the above.

To calculate the change in boiling point(Blogger isn't letting me use equation editor, get notes off moodle to really see this):

Change in Boiling Point=molal boiling point elevation constant x molality
Traingle T subscript b= K subscript b * m

To calculate freezing point depression, you use the same formula except the constant is different. The K subscript b is repaced with K subscript f.

The van't Hoff factor basically mens that if you have a mole of NaCl, and the ions dissociate when in water, you will get one mole of Na+ ions and one mole of Cl- ions. The van't Hoff factor is i so simply modify the previous equations by multiply i to the end like so:

Triangle T subscript f= K subscript f * m * i

That pretty much sums it up for new material covered today. Liebs demonstrated these new concepts with one demo involving 4 of us as water molecules, showing that the more solute added (balloons), the more interactions we had to make with it (touching each ion), which made it harder for us water molecules to turn into our gaseous state. Also, we took some club soda, stuck it into some ice and upon opening the glass, thus releasing the CO2 which had raised the freezing point, the club soda immediately froze.

Liebs also discussed some issues with the faulty Webassign that was due today, and said he would make corrections. I know it probably frustated myself as much as did to some of you (honestly, comment if you remembered how to use sig figs before this unit started).
That's about all though. Homework tonight is to do all the worksheets you have been given this unit that are due on the day of the test, as well as the 3 remaining webassigns also due on the day of the test.

Justin J., come on down, you are the next contestant on the price is right.

Nitrogen Party!!!

Today was a day that was filled with lots of nitrogen, in all three of its forms (including the rare solid nitrogen which few people have ever seen)! We started with some note-taking which you can get off moodle(not posted yet). The notes dealt with a new formula that is called the ideal gas law.

R= PV/NT (couldn't paste equations onto blogger from word)

R is the gas constant. It is equivalent to .082057. P is pressure (atm), V is volume(L), N is the number of moles, and T is temperature (K). This equation certainly is ideal for us because it relates all the variables into one law and we only need 1 circumstance rather than 2. For example, the combined gas law requires 2 circumstances. That is why you need 2 V's (V1 and V2) and so on. The combined gas law is below and it should be used when you have 2 circumstances.

P1V1/T1=P2V2/T2

With these two equations you can solve ideal gas problems which is on the worksheet you received today in class. After much convincing and pestering from the boys in row 1, they were able to convince Liebs to do at least one demo today. So Liebs took some of that awesome liquid nitrogen that he dumped on the floor yesterday, and threw it into the vacuum chamber that the balloon was in yesterday. Liebs lowered the pressure so much that the liquid nitrogen began to boil and finally it became solid. Though its appearance looked foamy, you'd never be able to feel it because once the pressure began to return to 1 atm, it quickly began to revert back to its liquid form. Finally, he dumped it onto the floor where it turned into a gas. That's all 3 forms of nitrogen. Somebody, though I can't remember who, coined the phrase nitrogen party. It certainly was!

Tonight's homework is the prelab for the Molar Volume lab and to do the ideal gas problem worksheet. The next scribe will be Rachel M.

"Life is like a garden: Dig it" ~A wise Man that is not Joe R

Sugary Beverages

Today in Chemistry, Mr. Lieberman quickly explained what to do for Part B of the Beverage Density Lab. Part B is nearly identical to Part A except now we were using actual sodas and other juices to caluculate density. By using a pipet to prcisely measure 5ml of our drinks, we then recieved the mass. The Volume was stil 5.00 ml, so once we got the mass, the density could be easily figured out. For those of you that still don't know how to find density, use this formula (D=M/V).

Once all of this was completed, Mr. Lieberman reviewed how to calculate your error %. Refer to Tom M's blog below to get that formula. We must also use our graphs in order to estimate the sugar concentration of our beverages and then use the formula, (Grams of sugar/Volume * Density)*100, in order to recieve the sugar concentration in our beverages.

This should be all the information necessary to complete the lab, which is due tomorrow. Tomorrow is a review day and it's late arrival!

Amar B. is the next scribe, enjoy sleeping in everybody!