Lab intro

This week we will be doing a lab in which you create biodiesel. The biodiesel is produced by a transesterfication reaction between a triglyceride fat or oil molecule and an alcohol. In the lab you will react methanol wiht cooking oil to synthesize biodiesel.


Here is a link to a more detailed explanation on how to produce biodiesel: http://journeytoforever.org/biodiesel_make.html

Here is a link to some more information on the national biodiesel board: http://nbb.org/

Biodiesel Video

This past week we have been working on a promotional video on the benefits of biodiesel. Here is the link to the video, watch it!!

Here is some more information on biodiesel, there are many more facts for this energy source that aren't included in the video: https://www.fueleconomy.gov/feg/biodiesel.shtml



Here is how biodiesel is created: http://biodiesel.org/what-is-biodiesel/biodiesel-basics

Shape and Electronic Geometry

When drawing the Lewis Structure of different elements and compounds, the structure has a shape and a geometry. The shape of the structure is determined by the number of bonds and direction of them about the central element as well as the number of lone pairs. The electronic geometry is determined the number of electronic domains around the central element.

Combining the two: http://intro.chem.okstate.edu/1314f00/lecture/chapter10/vsepr.html

Shape explanation: This site gives some background on the different shapes of the structures. http://www.smc.edu/projects/28/Chemistry_10_Experiments/Ch10_Molecular_Shapes.pdf

Here is an example of water, its shape is bent:

Electronic geometry explanation: https://ch301.cm.utexas.edu/help/ch301/geometries.pdf

Here is an example of H2O, its geometry is tetrahedral (this is because of the four different regions shown in the bottom left picture):

Lewis Structures

Lewis structures was the first things that we talked about, and this helped us learn everything after it. A lewis structure is a method of drawing compounds and showing their valence electrons, where bonds are shown with lines and lone pairs are shown with dots.

Here is a quick explanation on how to draw them: http://www.chem.ucla.edu/harding/lewisdots.html


Here are a couple compounds that you can practice drawing lewis structures for:

Here is a link to a video where they show you how to draw them. This can be helpful when you are drawing the ones from above: https://www.khanacademy.org/science/chemistry/chemical-bonds/copy-of-dot-structures/v/drawing-dot-structures

Here is a link to a website that provides any lewis structure you need so you can check your answers: http://www.wolframalpha.com/widgets/view.jsp?id=689aa5a01c216d8b16ed0250cebdc702

Here is an example of  the Lewis Structure for water.

Electronegativity

Electronegativity is just one of the things that we have talked about throughout this unit that goes along with chemical bonding. This number is placed on the periodic table and will tell you which elements have higher electronegativity than others. This number dictates the bonds they will make or whether or not the elements are non polar, polar, or ionic bonds. 

When you look at the periodic table, the electronegativity values tend to increase as you go to the right and up. This pattern will help when you are asked to put several bonds in order from most to least ionic without using the values themselves.

Here is a link that helps explain electronegativity: http://www.chemteam.info/Bonding/Electroneg-Bond-Polarity.html

Spectroscopic Analysis of Cr and Co Lab

In class we completed the Spectroscopic Analysis Lab in which we measured the % Transmittance of light through a solution at various wavelengths in the visible range. We measured the absorption and percent transmittance with blue and pink solutions.


Here is a link to more info of the Spec 20 equipment: https://www.dartmouth.edu/~chemlab/techniques/spectrometer.html

Periodic Trends

In class we had a lecture over all of the different periodic trends. The majority of the trends, we have learned, run up and to the left. There are four major trends: electron affinity, electronegativity, atomic radius, and ionization energy.

Electron Affinity: It is known to be the ease at which an electron may be added to an atom.

Electronegativity: It is the tendency of an atom to draw electrons toward itself when chemically combined with another element.

Atomic Radius: The size of the atom's radius.

Ionization Energy: It is the energy needed to remove an electron from a gaseous atom.


Here is an image summing all of the trends into one:




Here is a website elaborating on the trends: https://www.khanacademy.org/science/chemistry/periodic-table/periodic-table-trends-bonding/v/atomic-radius-trend