Let Chemistry Absorb You. Ha.

Alright, boys and girls, this here's a chemistry post and it's about to get real.

Mr. Lieberman reviewed the test with us, like a boss, and gave us two points because of an error and because of leniency. Then he reviewed with us the basic principles of solutions.

• A solute is the substance that is being dissolved
• A solvent is the liquid in which the solute is dissolved
• Solute dissolves in solvent
• Aqueous = solution with water as solvent

Easy, right?

A saturated solution is a solution where the solute has dissolved into it at a maximum. No more solute can be dissolved in this saturated state.

In the notes that Mr. Lieberman explained in class, there is a diagram of NaCl dissolving in H2O showing the driving forces that cause the dissolving of this solute, NaCl, into this solvent, H2O (most of the solvents in this unit will be H2O and all of them will be liquids! Awesome!). In the diagram, the H2O molecules, which are polar, attach themselves to the Na+ or Cl- atoms according to polarity. So an H2O molecule's negative pole will attach to the positive Na atom. And an H2O molecule's positive pole will attach to the negative Cl atom. This will pull the crystal-like structures of NaCl apart. This is a demonstration of an ionic solute dissolving by dissociation into its ions. There are two more types: Covalent solutes dissolving by H-bonding to water and covalent solutes dissolving by London dispersion forces (LDF).

This process is carried out instantaneously, it cannot be viewed through a microscope or observed at all, for that matter.

Furthermore, there are three stages to this same solution process explained in further detail here.

1. Primarily, there is the separation of a solute, and in order of this to happen, the solute's molecules must surpass their intermolecular forces (IMF) and it requires energy, making it endothermic.
2. Secondly, the separation of a solvent occurs when the solvent overcomes its intermolecular forces. This also requires energy, also making it endothermic.
3. Thirdly, the interaction of these two substances occurs. An attractive bond forms between the solvent and solute molecules and this releases energy, making it exothermic.

Phenominal! Now we understand the heat exchanges that occur within this process, let's continue!

We continued with the in-class notes and took a look at the factors affecting the solubility.

We know that Like dissolves like, which means that molecules with the same type of intermolecular forces will dissolve in eachother. E.g. dipole-dipole, Hydrogen bonds, and LDF.

Cool, huh?

Tell you what's not cool, that the raise of temperature in these solutions causes more collisions which allows easier access into these crystal structures, allowing for further saturation of a solution.

Finally, there is pressure. Solids and liquids are hardly affected by pressure changes in relation to solutions, but gas, under higher pressure, will have a higher solubility.

Well done, Captain, you have successfully acquired knowledge of solutions and can continue on your path to success. Enjoy your good HEALTH:

The next scribe is Becky N. (Rebecca N.)

Slam a revolving door

Chuck Norris can slam a revolving door
Besides from the obvious... today in class, first thing we did was review the forces. We reviewed the dispersion forces, dipole forces, and hydrogen bonding. for more information you can look below at Elim's post.
After our review, we started our lab.
This lab has 7 stations to observe trends and patterns in several properties of liquids and to use a model of intermolecular forces to explain the findings.

Station 1: Evaporation Rates
This station measured the rate at which the liquid evaporated. the rate that the liquid evaporates depends on the strength of the intermolecular forces between liquid molecules. liquids with the lowest evaporation rates have the strongest intermolecular forces.
Insert Photo here that I could not find

Station 2: Capillary Action
A liquid tends to climb up the walls of narrow columns, this is known as capillary action. This is based upon two forces: adhesive forces, and cohesive forces. The greater the cohesive strength, the more the liquid climbs the column. The greater the adhesive strength, the lesser the liquid climbs the column.

Station 3: Vortex Formation and Relaxation
If you swirl water, you get a water tornado. That's what this is, just making vortex's by swirling the liquids. The time it takes for a liquid to settle down from a swirl is different for all liquids depending on the intermolecular forces. the longer it takes to relax, the stronger the intermolecular forces are. We did this with three liquids: Water, Hexane, and Heavy oil.

Station 4: Viscosity or Resistance to Flow
Not every liquid flows at the same rate (compare water to waffle syrup). Viscosity is the property of a liquid which provides a measure of that liquids tendency to resist flow. Liquids with stronger intermolecular forces have a greater resistance to flow, a higher viscosity. We took the same three substances as station 3, and put them in test tubes. After that we timed the seconds of a marble falling to the bottom of the test tube. The faster it is, the lower the liquids tendency to resist flow, or the lower the Viscosity. The lower the viscosity, the weaker the intermolecular forces.

Station 5: Surface Tension
Molecules on the very surface of a liquid can form strong enough intermolecular forces between them to make their surface impenetrable. It's this surface tension (along with other factors) that make leaves floar on water. For this expirement, we had to lower a paperclip using a tray to try to make it float on the liquid. The liquid that the paperclip can most easily float has the greatest surface tension.

Station 6: Beading
Many liquids have a tendency to bead. For example water droplets that look circular, that is actually the water beading. This is cause by liquid molecules to form a strong intermolecular attraction with itself and curl into a spherical bead or droplet. The greater the strength of the intermolecular forces, the greater the tendency of the liquid to bead. If placed on a surface the liquid is attracted to, the liquids beads less. For this expirement we dropped droplets of liquids onto wax paper and our lab benches. We then made observations according to what beaded and what didnt.

Station 7: Freezing point and Boiling Point
unlike the other stations, this one was all on our packet. all liquids have a freezing and boiling point. These points depend on the strength of the intermolecular forces. Liquids with stronger intermolecular forces have higher boiling points. The graph on our paper is pretty straightforward if you just remember that.


Don't forget we have a ton of webassigns due on Friday as well as this lab.
This lab must also have a conclusion on a seperate piece of paper (though the data can all be in the packet).
The next scribe will be Emilio.

Polar and Non-Polar molecule

Today in chemistry class we started out by giving back pop quiz.
Mr. Liberman said most of us didn't understand about "stable."
When atoms are stable that means they don't want to bond or already bonded.
And he said we can't break octet rule except inside. In other words, outside of elctrons can't have electrons over 8.

After that he explaind about polar molecule and non-polar molecule by showing us a great demonstration.
He had two buret, a vertical cylindrical piece of laboratory glassware, that one has filled up with water and the other one has filled up with acetone.
By rubbing his hair with a balloon, that balloon has negatively charged.
As he moved the balloon close to the buret which has water, the flow of the water started to bend toward the balloon.  It happens because water is positively charged and it is polar molecule.
Theoretically, acetone has to be not bend but it did.  Mr. Liberman guessed the acetone mixed with water.
Anyway acetone can not be bend because it is negatively charged and non-polar molecule.

 + Non-Polar molecule
-charge is evenly spread out in the molecule
-NO NON-BONDING PAIRS

 + Polar molecule
-HAS NON-BONDING PAIRS
-the negatively charged center atom balances the molecule with positively charged outside of atoms

The main difference between non-polar and polar molecule is that non-polar molecule does not have non-bonding pairs and polar molecule has non-bonding pairs.

To determine polarity you should look for non bonding pair.

Mr. Liberman also explained different kind of forces-intermolecular, dispersion, and dipole forces.

Every molecules have intermolecular and dispersion forces.
Dispersion force is not that strong force but attractive.
Bigger molecule has lots of dispersion forces.
When he sprinkled acetone on his hand it disappeared very quickly but water did not.
This is a demonstration of dispersion forces.
Also we learned about hydrogen bonding which is strongest force.

I am really sorry that I couldn't explain very well..
So if you need more information about this stuff, I recommend you to visit here:
http://www.tutorvista.com/chemistry/difference-between-polar-and-nonpolar-molecules

And just a reminder, we have a lot of webassign to do.
Also we have a test on Friday.
The next scribe will be Alex K.

Sharing is Caring

Today, Mr. Lieberman had a pack of sour patch kids. He shared them with Zoe by giving her 1 of them and eating the rest. With a second pack of candy, he gave half to Zoe and the rest he ate. With a third, he gave the whole pack to Katie, taking none for herself. We learned that Mr. Lieberman was sharing his candy as molecules share electrons.
First, we learned about polar and non-polar. These are only between 2 nonmetals.
Polar covalent bonds are where electrons are not shared equally between molecules, and the electronegativity difference is between 0.4 and 1.7.
Non-polar covalent bonds are where electrons are shared equally between molecules, and the electronegativity different is between 0 and 0.4.
An example of a non-polar covalent bond is C-C. It is said to be like "tug of war with your twin". No one would win and the forces trying to win, or gain the electrons are equal, so the electrons would be shared equally. The electronegativity for the two atoms are the same, so they are equally pulling for the electrons. This is the scenario where Mr. Lieberman gave half his candy to Zoe and kept half for himself.
An example for a polar covalent bond would be C-F. The electronegativity for fluorine is strong than that of carbon, and therefore, there is an unequal share of electrons, because flourine would be winning the game of tug of war with carbon. Fluorine becomes more negative because the electrons are closer to fluorine than carbon, even though they are still shared with carbon, so that would mean fluorine is partially negative. Carbon has less of a pulling force on the electrons so it is partially positive. The opposite ends (+ and -) create a dipole. This is the scenario where Mr. Lieberman gave one piece of candy to Zoe and ate the rest.
Ionic bonds are where one molecule gets all the electrons, having a complete transfer, even though this is considered sharing. The electronegativity of one nonmetal atom is so much greater than the other metal atom that it pulls the electrons away. This is the scenario where Mr. Lieberman gave all his candy away to Katie.
We also had a pop quiz at the end of class.
Have a great rest of the weekend everyone!
~Kaitlyn Y.
The next scribe will be Elim.

Build the Big Ones Lab

Today in class we finally got to a a lab! It was called Build the Big Ones. The big ones refers to molecules with more than one central atom. The molecules we worked with were ethanol, acetic acid (vinegar), serine, and styrene. We had to build each molecule using spheres, wooden sticks , and metal springs. The wooden sticks represented a single bond and the metal springs represented double bonds. As explained in the directions, a black sphere is carbon, a yellow sphere is hydrogen, a red sphere is oxygen, and a light blue sphere is nitrogen. Here are the pictures for each molecule:


ethanol


acetic acid


serine


styrene

For each molecule we had to determine the central atom, the geometry of the atom, an example would be tetrahedral, the bond angle for that geometry and the hydridization. Here is what me and my partner Katie I. cam up with:

Lastly, we had to do our conclusion for the lab and if any of you had trouble, this is the conclusion Katie and I came up with:

I hope our data table and conlcusion help! Well that was all we did in period 6 today.
The next scribe is......................................Kaitlyn Y.