Gas Law

 Is there a relationship between volume and pressure?
- In our school lab as a group we have done specific measurements to prove how pressure and volume are related (according to Boyle-Marriot law, explained below). Using this apparatus:

The apparatus on top is used by this way: you pull the top handle until the black part (which is inside the container) and then you put the red handle (which is at the right, jus beside the indicator of the pressure) at the ways that no air can get in or out. gradually you push the top handle, stoping when therearetwo or three ml than befor and you record the pressure that the indicator tells us. 

 These are some members of our group writting downthe data that we found out through this experiment.

-Our table, graph and results:

This graph represents our study in the lab about the relationship between the volume and the pressure of a gas in a container. With an specific instrument we took a container with 65 ml of volume and we placed the pressure at 0, then we started to decrease the volume, so the pressure increases, as we were reducing the volume the pressure was increasing and we record the data so we can make a reliable graph. 

Boyle-Marriot law

                                           

This image represents the Boyle-Marriot law, that consists in the following: when the volume of the container decreases, the pressure increases. The graph beside the animation that moves up and down in an exponential way, tells us that the way the pressure increases is inversely proportional to the way the volume decreases. There is a simple form of proving it, you take the measurements of a volume and its respective pressure, and you multiply it, then you take another measurement of a different volume with its different pressure and multiply also these ones, the result would be the same (P1 x V1 = P2 x V2), because one increases while the other one decreases.
The formula to calculate the Boyle-Marriot law is this one:
VP = k

Conclusion

When volume is reduced, the pressure is increased, this is because the particles of the gas get squashed: the same number of particles are put in gradually less space, so the particles are nearer to each other, increasing also the density of the gas. This conclusion fits perfectly with Boyle-Marriot law.

WORK DONE IN SAN FRANCISCO DE PAULA SCHOOL CHEMISTRY LAB
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References:

http://en.wikipedia.org/wiki/File:Boyles_Law_animated.gif

THE PROPERTIES OF MATERIALS

THE PROPERTIES OF MATERIALS

IN THE LAB:
We have tested three substances and their properties. They properties such as: solubility in water or acetone, in they conduct electricity in solid state, their physical state at room temperature (27º approx.), and if they melt with an increase of temperature, all of those together help us determine if they are covalent, ionic or metallic.

       SOME OF THOSE CHARACTERISTICS WEREN'T TESTED BECAUSE THERE WEREN'T NEED TO DETERMINE THEIR TYPE

In this lab session we have stated our results in a table and then we have answered some question which helped us to improve our understanding about properties of materials and the types of compounds we are looking at

OUR RESULTS:

QUESTIONS & ANSWERS:

Why do Ionic compounds dissolve in water?

Ionic compounds on the other hand are formed when from the electrostatic attraction between oppositely charged ions. The electrons of an ion are transferred to another atom. The atom that loses an electron becomes a positively charged ion while the one that gains the electrons becomes the negatively charged ion.


Why do covalent compounds dissolve in acetone?

Napthol, C3H6O,  as covalent compounds and acetone ,(CH3)2CO,as an organic solvent, Napthol is soluble in it because they are made of organic elements, which they attract they particles of the solute by the particles of the solvent been easier to break down into a solution.

Why do metals conduct electricity?

Metals conduct electricity because their atoms and outer electrons are not kept with a specific atomic nucleus and due to the orientation of the atoms in the pure metals or molecules to mixed metal. There are a lot of electrons moving that are liberated to be in motion in response to an electric voltage, a greater uniformity of atomic orientation, the greater conductivity.
The metal atoms have many free electrons in their orbits (many electrons surrounding the atom) and these electrons are going to conduct electrical current because it has unfilled spaces in the valence band energy, 
Staying in its original energy band, this movement of electrons contributing to the establishment of an electric current.

Why do the covalent compounds NOT conduct electricity?
Covalent compounds do not conduct electricity because they don't have free electrons and no ions. 

Why do ionic compounds have such a high boiling points?

The ionic compounds have electrostatic attraction and a crystal lattice between them. This creates a strong bond, which can only be separated by high temperatures, that melt the crystal so the particles can separate. 

Why do metals have such high boiling points?

There is NO IONIC BONDING in metals. It is metallic bonding, which is something different.
Metallic bonding involves a "sea of electrons" that extend over the metal atoms. There are strong forces of attraction between these electrons and the positive nucleus of the atoms, which are relatively difficult to overcome. This explains the high melting and boiling points of metals.


WORK DONE IN SAN FRANCISCO DE PAULA SCHOOL CHEMISTRY LAB
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References:

http://physicsmadeeasy.wordpress.com/chemistry-notes/bonding/

http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html
http://course1.winona.edu/sberg/241f03/Lec-note/Chem-1.htm
http://www.seas.upenn.edu/~chem101/sschem/metallicsolids.html

Schlenk tube preparation

How to prepare a Schlenk tube?

This is an important skill which has to be performed correctly in the lab, and you ought to know it in order to perform some experiments in the Chemistry. 

They are useful dealing with noble gases such as argon and helium, they also are places where you could create a vacuum to work safely with reactive substances.

Here we have two briefs made video which explains how to prepare a Schlenk tube properly. To ensure the security during an experiment.

To prepare a schlenk tube we need:

- Rubber-band:

- Vaseline: 

- Silicon cap: 

The result will be this: 

STEP BY STEP INSTRUCTIONS:

"To prepare a Schlenk tube you need to follow these steps"

- First you need to spread out the Vaseline around the stop cog, avoiding the side holes. 

- Secondly you must introduce the stop cog into the hollow of the Schlenk tube and then you take a rubber band. Next you need to twist the rubber band twice, and you need to follow the procedure of all the movements which are on the video, so that finally the stop cog will be secure and can't get out the hollow of the tube. 

- Finally you put the rubber stopper in the hole in the top of the Schlenk tube, and you turn around the tube, and finally to prevent leakage of fluid and make it sure, you have to take a rubber band and encircle it around the rubber stopper. 

WORK DONE IN SAN FRANCISCO DE PAULA SCHOOL CHEMISTRY LAB. 

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References 

http://www.res.titech.ac.jp/~smart/facilities/Schlenk.JPG

http://www.area-integral.net/cat/img/OFICOMS28731.jpg

http://upload.wikimedia.org/wikipedia/commons/thumb/3/33/White_Petrolatum1.jpg/220px-White_Petrolatum1.jpg

http://img.alibaba.com/photo/543053661/butyl_rubber_stopper_for_blood_collection_tube.jpg