Monday may 17th, 2010

In today's class we extended our knowledge in the area of organic chemistry.

-A Hydrocarbon is an organic molecule made up entirely of Hydrogen (H) and Carbon (C).

-It is also the simplest form of organic molecules.

There are two forms in which these molecules can take:

*Linear; appearance of molecule structure is "----------------" and may have branches as the image.

*Cyclic; is a molecule which has no beginning or end. appearance as so:

We continued class by looking at the subcategories of linear molecules. Which are:


-Alkanes (single bonds)
-Alkenes (double bonds)
-Alkynes (Triple bonds)


Are class continued by looking specifically at the subcategory of Alkanes. We were going to begin to combine the prefix's we had learned with hydrocarbons. We would later be able to identify and create organic molecules that where hydrocarbons, had a linear shape, and were Alkanes.


In this molecule, we may identify 3 Carbons, and 8 Hydrogens, in a linear shaped molecule.
Its name consists in: (hydrocarbon)
3 Carbons (C) = prop as the prefix
8 Hydrogens (H) +
And as it only has single bonds it is an Alkane, meaning it ends with ane.
----------------------------------------------------------------------------------------------
Propane (common household gas)


Example #2



In this molecule, we may identify 6 Carbons (C), and 14 Hydrogens (H), in a linear shape molecule. Its name consists in: (hydrocarbon)
6 Carbons (C)= hex as the prefix
14 Hydrogens (H) +
And as it only has single bonds it is an Alkane, meaning it ends with ane.
---------------------------------------------------------------------------------------------------------------------------------------
Hexane




We continued the class by learning how to identify branches and what to call the molecule with specific branches and those that pertained to linear shaped molecules.



The process in which to discover the name of such molecule:
1) Identify the longest chain , which in this case is the 5 Carbons shaded in blue. You may identify it as pentane from this point as well.
2)then you may identify the branches but numbering 1-5 starting from the side nearest to the branch. In this case it doesn't matter what side it is as the branch is located at "3" from either side.
3)Now naming the branch comes next, you use the same prefixes for the amount of carbons in the branch. In this case it is "Meth"and as its a part of the branch it is called Methyl, only adding yl.
4)Now you may put the information you discovered as follows:


Organic Molecule: 3-Methyl Pentane


Note: you must always order the branches alphabetically!!!!!!!!!!!!!!!!


Example #3


1 2 3 4 5 6 7 8 9 10
CH3-CH2-CH2-CH-CH-CH2-CH2-CH2-CH2-CH3
l l
CH3 CH3
1) The longest chain is 10 Carbons long, meaning it is a decane.
2)The branches are nearest to the left side of the chain. So we will number the chain for locating the branches. So the branches are located at 4 and 5.
3)Both branches are Methyl (due to one carbon in each branch).


Organic Molecule: 4,5-dimethyl-decane




Example #4


In this example it will remind you that the main chain has to be horizontal.




CH3 l
CH2
1 2 3l 2 1
CH3-CH2-C-CH2-CH3
l
CH3


1)The longest chain s 4 Carbons long, this is how it looks in a simpler form:
CH3
l
CH2
l
CH3-CH2-C-Ch2-CH3
l
CH3


It is a pentane.


2)The branches are equal distance from either side. It is located at "3"
3)In one branch it is methyl, and in the other it is bimethyl, adding them together gives you trimethyl.


the organic molecule: 3,3-trimethyl-pentane

Stefano Pinzon

Friday May 14th, 2010

First journal of the 3rd partial (time passes so quickly). Today we saw the intro of the 3rd partial main theme: ORGANIC CHEMISTRY

First of all, what's Organic Chemistry? simply, it's the the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds.

Now, knowing that we're going to hear carbon so many times that technically we are going to dream with it, we'll see an interesting characteristic of this necessary element for life.

Depending on the length of the carbon molecule and it's shape, the molecule is part of something different (if it has linear shape it forms one thing, if it has an "L" shape it forms another thing, etc.)

The parts of an organic molecule are:

• Prefix.- The first part of the molecule's name
• Suffix.- The second part of the molecule's name

The prefix indicates the number of carbons that are in the molecule:

1. Meth (Methane)
   
2. Eth (Ethanol)
   
3. Prop (Propane)
4. But (Butane)
5. Pent
6. Hex
7. Hept

There are different types of formulas that we're going to see and use in the rest of the semester, and they are:

• CH4 -----> Molecular Formula (it tells us what do we have)
• H-C-C-C-C-H -------> Structural Formula
• CH3-CH3 -------> Condensed Formula
  

The phenomenon of using the same components but making different structures (and consequently different physical objects) is calledIsomery. A more "official" definition of it is this:

Isomery: "A molecule with the same molecular formula, but different structural formula".

Homar Hurtado

Monday May 3rd

Today we learned about something new, it is called OSMOSIS. First of all, what is osmosis? (I didn't get it on the first time neither).

Osmosis is the movement of water through a semipermeable membrane; in high school words, "Osmosis is the action in which a cell let water pass through its wall (membrane)", we used the Girls and Boys example, but because of the dirty mind we have we understood very well and also laugh in the process.

Also, to understand better the teacher used the example of the fresh water fish and the salt water fish: If we put a cell of a salt water fish in a tank with fresh water a lot of water is going to enter to the cell and eventually is going to blow up (the cell, not the fish XD). The opposite thing occurs with a fresh water molecule and a salt water tank (the cell "dries up").

Another concept we saw was the Dyalisis: it is the movement of solute through a semipermeable membrane (the cell lets the particles of solute to go outside or inside so the concentration of both can be equal).

Homar Hurtado

Friday April 30th

Well, today we saw new things (i'm not saying that in the past classes we saw the same things, but you understand me), the subject was SOLUTIONS, SUSPENSION, COLLOIDS

We already know what is a solution (we saw it like 4 times), but what is a suspension (no, i'm not talking about cars XD) and acolloid?? and what do these concepts have in common???

Well, these are mixtures that use water as a solvent (aqueous mixtures), yes, as simple as that jejeje.

Characteristics:

• Solutions: These are homogeneous and have small particles (0.1 - 1 nm) Example: Ions, Atoms, Small molecules
  
• Colloids: Are heterogeneous, they have "medium" size particles (1 nm - 1000 nm) Example: large molecules
• Suspension: These are heterogeneous too, and have BIG particles (1000 nm and greater) Example: Aggregates

I don't know if someone else has this problems, but i didn't know what was a Nano Meter or a Micro Meter, but now i know:

Milimeter/100 = Micro Meter Micro Meter/100 = Nano Meter (a really really really REALLY small particle)


Also, we saw 3 more concepts:

• Tyndall Effect: The scattering of visible light by colloidal particles and suspensions aggregates is called The Tyndall Effect. In my words it's "the more photons you have bouncing with particles, the less light you can see"
• Brownian Motion: Is the chaotic movement of the particles
• Emulsion: It's a special kind of mixture, it is a colloid, a liquid solvent and a liquid solute. "A colloidal dispersion of a liquid and a liquid".

Homar Hurtado

Monday April, 26th

Mixtures and Solutions

In today´s class we have begun a new unit called "Mixtures and Solutions".
We began learning such concepts and their relationship with matter.

----------------Matter------------------

l l Substances Mixtures

(can be seperated by chemical means) (Physical)

l l
----------l------------ ------------l-----------
l l l l
Element Compound Homogenous Heterogenous
(not seperated) It is made by two Can not identify parts Its parts can be identified
It is the pure form of something or more atoms
made from one specific atom

It is key to remeber that an element is singular, or just one atom and a compound is two or more atoms.

After viewing the relationships of mixtures and solutions with matter, we discussed common, every day examples of Homogenous and heterogenous.


A great example for Heterogenous is a Salad. You can see the component/ingredients (lettuce,tomato, carrot, etc), which are the parts that can be identified

A common example of Homogenous is coffe. Your not able to identify its igredients or components to make the coffe, which means you are not able to identify its parts.


Next we encountered a new term,

Phase- "the part you identify as a whole (profe Ariel)"

E.g, When you add oil to water you will be able to identify the phases as they are distinctly seperated from each substance to another, this is due to polarity (the charge of particles)

Solutions

There are two parts to a solution
1. Solute-which is the particle to be dissolved
2.Solvent- matrix where the dissolving takes place.

A solute disperses into the solvent, giving you a solution.
!!!!!!!!!!!!!!!!!!!!SOLUTIONS ARE ALWAYS LIQUIDS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!! IN ORDER FOR A SOLUTE TO DISSOLVE IN WATER IT HAS TO BE POLAR!!!!!



A good example of a solute and a solvent is chocolate milk

the milk is the solvent and the chocolate powder is the solute.


At the end of class we acknowledged methods for mixture seperation.

The first was filtration- which would seperate the mixture bye the size of its ingredients/components.




The second was Distillaton-is a method of seperating mixtures based on differences in their volatilities in a boiling liquid mixture.


...

View image on Bing

Stefano Pinzon

Monday March 8th, 2010

To start the class we learnt a new term,

Percent Yield

With this term, there are two types of such meaning,

1.Actual Yield: The amount of product that actually forms is carried out in the lab.
2.Theoretical Yield: the maximum amount of product that could formed from given amounts of reagents.

An example: Xgrams + Ygrams= 200g in a theoretical yield,
Xgrams+ Ygrams = 195g as a result of the actual lab, this is the actual yield.

The Percent Yield is used to compare the theoretical yield to the actual yield. And to demonstrate this we use ratios.

Example 1: If your T.Y(theoretical yield) is 200g, and your A.C(actual yield) is 195, your ratio will look like this:

195x 100%=97.5%
200

so your 97.5% is your ratio of T.Y to A.Y

Concentrations of Solutions

Before beginning the class we reviewed the meaning of Concentration

Molarity:measurement of the expressed amount of moles you have disolved into the solution.

To solve questions related to concentration, you will need to use a formula.

Formula: mass = moles=concentration=molarity
volume litres

Example: you have a 1 M solution o NaCl. How many grams of salt are in 500ml of solution?

Step1: calculate how much of molarity you have with 500ml.

1 ml= x molarity cross multiplication
1 lt=.500ml

x=.5ml

Step 2: now calculate how many grams will you get with .5ml.

1ml=58g (NaCl)
.5ml=x grams

x=29grams of salt

Answer is 29 grams of salt

*in some questions it may ask for the molarity were you do the whole same process but backwards.

Note: it is important to capitalize the M for Molarity.

Stefano Pinzon

Monday March 1st, 2010

In today's class, we came upon two new important terms. The first one:

LIMITED REAGENT: it is the reagent that determines the amount of product that can be formed by a reaction. The reaction occurs only until the limited reagent is used up.

The second term is EXCESS REAGENT: the unlimited amount of reactant. But the term is self explanatory.

In our exercises we learnt how to identify the reagents.

For example: using the analogy of recipes there can only be a limited amount of sandwiches produce with 4 slices of bread it is known to be the limited reagent.

Practice #1

Information:Copper reacts with sulfur to form copper (1) sulfide according to the following equation: Atomic Mass

2Cu+S-->Cu2S Cu=63 S=32

What is the limiting reagent when 80g of Cu reacts with 25g of S?

Step #1: If 1 mole of Cu (copper) weighs 63, how many moles are there if you have 80g

your equation should look something among the lines of this

1 MOLE of Cu = 63g using cross multiplication

X MOLES of Cu = 80g

X = 1.269 or 1.27 moles

Step #2: If one mole of S (Sulfur) weighs 32g, how many moles are there for 25g

your equation should look something like this

1 MOLE of S=32g using cross multiplication

X MOLES of S=25g

X=0.781 moles

Step#3: In this step you will be able to compare the amounts and quantities

If there is one mole of Sulfur and gives you 2 moles of Cu as a product, you will be able to calculate the end result with different amounts of moles like this:

1S--->2Cu Cross multiplication 1S--->2Cu

0.78moles of S --->X X moles--->1.27

X= 1.56 moles X=0.635 moles

Step #4: answer the question by comparing the amount of moles from the 80g of Cu (1.27) to the result you got from step #4, and depending on the contrast, in this case the answer from step #1 is less than 1.56 than your are able to say that

Answer: 1.27 moles of Cu is your limited reagent

0.78 moles of S is your excess reagent

Your process you do is not obligatory to do the same, it can be recommended, but the best method is the one you understand.

Stefano Pinzon