Biodiesel production

The "sustainable energy" is the energy that is produced and used in ways that support long-term human development in the social, economic and ecological.

Access to energy, including sustainable energy, is inseparable from a sustainable future for the developing world. Access to energy transforms the lives of those who lack energy resources and improve their living standards.

Energy services have a profound effect on productivity, health, education, climate change, food security and water and communication services. Lack of access to clean energy, affordable and reliable hinders social and economic development. Some 1,400 million people lack access to modern energy, while 3,000 million depend on "traditional biomass" and coal as the main energy sources.

Biodiesel appears as an alternative to petroleum fuels, but no longer controversial.

This topic has aroused the curiosity of many people, and so I consider it is important that teachers of chemistry are informed about biodiesel production enterprises in our country. This is an important issue that can be worked in different years of high school.

the main producer of biodiesel production in Uruguay is the plant of the company ALUR. For further information about biodiesel production look at an interesting video in the following link: 

http://www.alur.com.uy/images/videos/2012/biodiesel/biodiesel-1.html

Spirometry: redox reactions

The alcohol digested by a person is not chemically modified in the bloodstream. As blood passes through the lungs, some of the alcohol molecules is immersed in air bags lung (alveoli), because of the alcohol in the blood is evaporated due to its high volatility. The alcohol concentration in the alveolar air is related to the concentration of alcohol in the blood.
Because alcohol exhaled in breathing can be determined by various mechanisms and through an established relation the concentration of alcohol in blood can be determined . This allows to know the relation of alcohol in blood without having a sample of it, but simply with breathing and get it.

The alcohol in  breath is examined using a device called a breath analyzer.

The chemical operation of these devices is explained by a redox reaction.
A driver's breath sample is introduced into the analyzer where it reacts with potassium dichromate in an acidic medium.
The reaction is represented by the following equation:

3CH3CH2OH + 2K2Cr2O7 + 8H2SO4___________  3CH3COOH + 2Cr2(SO4)3+2K2SO4+11H2O

In this reaction, ethanol is oxidized to acetic acid and chromium (IV) ion dichromate, reddish-orange ion is reduced to chromium (III), green. The intensity of the color change is directly related to the level of alcohol in exhaled air and therefore also in the blood.
Silver nitrate used is a catalyst which causes the reaction to go faster.

The theme redox reactions it would work only in the second year of high school where the student already has got various skills needed for the construction of this new knowledge.
I leave an activity where they can work the above.

Experimental Activity

Redox reactions

Previous activities:

> Find out about the alcohol content of different drinks usually consumed.

> Make calculations of the shots required to prepare 100ml of solution at different concentrations.

Objective:

> Explain the operation of the spirometer through redox reactions.

> Observe the color change that occurs in response to varying concentrations of alcohol

Rationale:

                                       > Redox reactions

                                       > Oxidizing agents, reducing

                                       > Alcohol

                                       > Limiting reagent

Materials:         

                       > test tubes

                       > Tweezers

                       > Bohemian glass

                       > Flask

                       > Burner

                       > Pipette

                       > Ethanol 95% v / v

                       > Potassium dichromate 5% m / v

                       > Distilled water

Procedure:

                   > Prepare 100 ml of an ethanol solution of 5% v / v, 10% v / v 20% v / v respectively.

                   > Place in 3 test tubes 10 ml of potassium dichromate 5% m / v

          > Place in 3 tubes the same volume of 0.5 ml of ethanol solution with different concentrations.

                   > Place the tubes in water bath for a few minutes and observe the changes

This practice is intended students to link the themes from a corpuscular view with macro phenomena. The concentrations of ethanol previously reacted are linked with different graduations of the most common beverages.

This is a practice that is not a quantitative but rather qualitative.

bibliography:

                 > Sanmarti, Neus "The design of teaching units" Autonomous University of Barcelona

                 > Laborde, Gustavo "designing lesson plans" and "Planning in Education"

                 > Atkins "principles of chemistry"

They were also used to support materials during the course of General Chemistry I

My conception of science

Once you set a theme or concept there are several ways to approach the teaching of it.

Personally, I consider appropriate to develop teaching strategies based on a model of conceptual change because this way the concept really can be assimilated.

A strategy based on conceptual change involves considering the previous ideas of students.

To change previous wrong ideas we need a methodology in which they figure out this ideas are not true actually. We force to face up situacions which these wrong concepts don't solve the problem and it's here when the new right concepts appear.This is the start to make change.

The teacher plays a key role in the process of teaching. They should not introduce concepts already finished or abstract but they should encourage them with a spirit of inquiry and guide them to construct knowledge.

It is necessary to take into account the student context in which this process takes place.

The teacher must be able to transcend the abstract idea of science to be applied in the day-by-day situations. Science should be used as a tool to understand the world around us and not as a set of abstract knowledge.

Chemestry teacher

From the origins of the universe, so far, a series of transformations have shaped our world. There are two key players in these transformations: matter and energy are converted into each other at every turn.

Every day, without realizing it, we use the transformations of matter and energy; for example when we turn the gas or firewood into heat through combustion.

Chemistry is the branch of science that studies matter and its transformations, and personally I consider it very attractive.

It's for this reason and for my vocation in teaching chemistry that I decided to follow this career. 

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