Experiment nº 6 : Experiment on vapor pressure in alcohols

Objective:
To calculate the pressure of hexanol while we made a vacuum, compare them with the results obtained by our classmates which are working with methanol, ethanol, propanol, butanol, pentanol, heptanol and octanol, and learn how to create a plastic model of a molecule of hexanol.

Materials:

• Hexanol
• Shlenk tube
• Stand
• 2 Rubber bands
• Clamp
• Interphase
• Gas sensor
• Rubber tube
• Computer with Logger Pro.

Background by Elisa Millán:

According to the Encyclopedia Britannica vapor pressure  is  the  pressure exerted by a vapour when the vapor is in equilibrium with the liquid or solid form, or both, of the same substance—i.e., when conditions are such that the substance can exist in both or in all three phases. Vapour pressure is a measure of the tendency of a material to change into the gaseous or vapour state, and it increases with temperature. 

Oral Procedure by Claudia Falcón:

Results:

Table 1: Vapor pressure depending on the number of carbons

Graph 1:

Explanation of best fitting line:

The relation between the variables is that the lower the number of carbons, the higher the vapour pressure. Meaning, in the graph the best fiitting line has an exponential appearance due to the  inversily proportional relationship between the independent and dependent variable.

However, in order to desing a straight fitting line, we just need to calculate the inverse of each pressure value and use them as the independent variable. If we apply it, the regression coefficient might be altered.

Conclusion of the Experiment by Carmen Lérida:

Observations of the graph by Marina Bayón:

Scientific reasoning:

The scientific reason of the results obtained in the lab is that when an alcohol contains a huge amount of carbon atoms the chain of carbons will be more fragile, meaning less temperature is needed in order to brake the carbon atom chain. Therefore, when we need less temperature that alcohol will excert less vapor pressure. 

For instance, propanol exerts less amount of vapor pressure as the chain of carbons is only composed of three of them, while ethanol change is created by six carbon atoms so the chain is more fragile, consequently it will need less tempeture and it will exert less amount of vapor pressure.

Bibliography: 

• En.wikipedia.org (2013). Hexanol - Wikipedia, the free encyclopedia. [online] Retrieved from: http://en.wikipedia.org/wiki/Hexanol[Accessed: 23 Mar 2013].
• En.wikipedia.org (2005). 1-Hexanol - Wikipedia, the free encyclopedia. [online] Retrieved from: http://en.wikipedia.org/wiki/1-Hexanol [Accessed: 23 Mar 2013].
• En.wikipedia.org (1892). Chemical nomenclature - Wikipedia, the free encyclopedia. [online] Retrieved from:http://en.wikipedia.org/wiki/International_Union_of_Pure_and_Applied_Chemistry_nomenclature [Accessed: 23 Mar 2013].




Encyclopedia Britannica (n.d.). vapour pressure (physics). [online] Retrieved from: http://global.britannica.com/EBchecked/topic/623199/vapour-pressure [Accessed: 7 Jun 2013].
• Ivy-rose.co.uk (2012). Naming Alcohols : Names of Alcohol Compounds : Organic Chemistry. [online] Retrieved from: http://www.ivy-rose.co.uk/Chemistry/Organic/Naming-Alcohols.php [Accessed: 23 Mar 2013].
• Pubchem.ncbi.nlm.nih.gov (n.d.). 1-hexanol - PubChem. [online] Retrieved from: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=8103 [Accessed: 23 Mar 2013].
• Rsc.org (2013). 1-Hexanol- Learn Chemistry. [online] Retrieved from: http://www.rsc.org/learn-chemistry/resource/rws00007812/1-hexanol [Accessed: 23 Mar 2013].
• Sigmaaldrich.com (2012). 1-Hexanol, reagent grade, 98% | CH3(CH2)5OH | Sigma-Aldrich. [online] Retrieved from:http://www.sigmaaldrich.com/catalog/product/sial/h13303lang=es®ion=ES [Accessed: 23 Mar 2013].


Processing Data using Excel

How to make a table using the values from the Logger Pro  by Claudia Falcón:

 

How to make a graph using the table above by Carmen Lérida:

 

 

Experiment nº5: Practical use of Gay Luissac's law

Objective:
The aim of the experiment is to observe and understand how the pressure of a gas changes in relation with the temperature at which the gas is submerged.

Materials:

• Container
• Stand
• Clamp
• Bunsen Burner
• Wood pieces
• Tripod
• Schlenk
• Water
• Lighter
• Electronic thermometer
• Magnet
• Magnetic stirrer
• Manometer

Explanation of the relation between temperature and pressure. (Elisa Millán)

According to Gay-Lussac’s law, for a given amount of gas held at constant volume, the pressure is proportional to the absolute temperature. As we can see in the image above the relationship between volume(y) and temperature(x) is a directional proportion for a constant pressure but when volume is held constant we will find an inverse proportional relationship between pressure(y) and temperature (x). We can observe this relationship using the following formula:

P/T=K

Oral procedure by Marina Bayón Rueda:

Results:

Conclusion1 by Carmen Lérida Borrero:

Conclusion 2 Claudia Falcón Morales: 

References used in order to explain the Gay-Lussac's law:

• Chemed.chem.wisc.edu (n.d.). Untitled. [online] Retrieved from: http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/Gay-Lussac-s-Law-952.html [Accessed: 9 Mar 2013].
• Grc.nasa.gov (2008). Charles and Gay-Lussac's Law - Animated. [online] Retrieved from: http://www.grc.nasa.gov/WWW/k-12/airplane/aglussac.html [Accessed: 9 Mar 2013].

Experiment nº4: Introduction to galvanic cells and redox couples.

In this class there were two tasks performed:

Objective 1:
The aim of this lab session is to prepare a battery with the following redox couples:

In order to achieve this you will use a polymeter and a salty bridge.

Objective2:
The aim of this lab session is to obtain energy from the mixture of two redox couples.

Materials:

• Copper(2+)
• Elemental iron
• Elemental zinc
• 2 test tubes
• Test tube rack

Procedure

1.       Choose  2 redox couples which we are going to work with.

2.        Get two small test tubes.

3.       Mark each test tube with the corresponding couple, in this case Cu²⁺with Fe and Cu²⁺ with Zn.

4.       Pour the copper in each test tube until it reaches half of it.

5.       Add the zinc to one test tube and iroin to the other.

6.       Wait until it reacts.

7.        Note the reactions you see.

 Performing the experiment by Carmen Lérida Borrero

                                                                Conclusion

Explanation of the reactions by Marina Bayón Rueda

Reflection

Weak and strong points by Elisa Millán Chica

Usefulness of this experiment by Claudia Falcón Morales 

Experiment nº3 : Titration

Objective:

The aim of this report is titrate the potassium permanganate (KMnO₄). In other words, to observe how many ml of potassium permanganate we need to add to the oxygenated water (H₂O₂ ) until it becomes a saturate reaction.

Materials:

• 2 test tubes
• Volumetric flask
• Burete
• Clamp
• Stand
• Pipette
• Beaker
• Ptassium permanganate (KMnO4)
• Oxigenated water (H2O2)
• Glass

Oral Procedure by the 4 members of the group:

Example of Redox through titration by Elisa Millán:

Conclusion by Marina Bayón:

Reflection by Carmen Lérida:

Experiment nº2: Investigation about the characteristics of different elements and compounds.

Objective:

The aim of this experiment is to look for 18 characteristics of 3 different elements or compounds per pair and create a table which includes this information.

How to obtain this 18 characteristics:

Materials:

• 6 test tubes 
• Spatula
• Litmus paper
• Water
• Organic solution(ethanol)
• Magnet
• Bunsen burner
• Lighter
• Stirring rod
• Electrical circuit
• Acid(pure HCl)
• Microtitration plate 
• Test tube rack

Procedure:

First select the materials that would be needed in order to fulfil the experiment.

Follow the following instructions in order to create your own tables:

1.  Name: we look the name in the label of the bottle.
2.  Element/Compound: we must know from previous concepts.
3.  Chemical representation: for a compound we must look it in the bottle and for an element we look it in the periodic table.
4. Smell; strong/mild: we smell it, but we need to ask firstly to our teacher and we must be careful with the acids.
5. Colour: we can see it.
6. Shine: we also can see it.
7. Aggregation state: we also see it.
8. Melting point: we look it on the internet.
9. Boiling point: we look it on the internet or we can obtain it by heating it with the use of a bunser burner and a thermometer.
10. Magnetism: we can test it with a magnet.
11. Combustibility: we can know it by burning a small amount of the substance.
12. Solution in water: we can get it by pouring in a test tube water and some substance and see if it has dissolve.
13. Solution in organic solvent: we can get it by pouring in a test tube any type of organic substance and some of our substance, and see if it has dissolve.
14. Reacting in water: we can know it by pouring in a test tube water and a bit of our substance and see if its reacts.
15. Reaction in organic substance: we can know it by pouring in a test tube any type of organic substance and a bit of our substance and see if its reacts.
16. Reaction in acid: we can know it by pouring in a test tube any type of acid and a bit of our substance and see if its reacts.
17. PH of organic solution: we get it by wetting a little piece of PH paper with our substance, and see the reaction.
18. Conductivity: we can test it with a small circuit which contains a bulb in it. We use our substance as a bridge. If the substance conducts electricity the bulb will give light, if not it will stay the same. 

Practical procedure: Testing for the  characteristics:

Aluminium

Conductivity

Magnetism

Introduce into an organic solvent

Pour into an acid

Adding pure HCL into the aluminum.

Aluminum in water.

   Aluminium in a 2 M concentrated acid.

General Evaluation by Marina Bayón Rueda:

Melting and boiling point by Elisa Millán Chica:

In order to fulfil this part of the experiment you should take a series of precautions. First you should tilt the test tube a little bit. Then you should make sure it is not pointing t any of the person who are in the lab and are near you. And finally you should shake the test tube in and out the flame frequently. 

Boiling point by Carmen Lérida Borrero:

Results obtained:

In the fourth row you can observe the element which we have been working with in this experiment (Aluminium) and the result obtained after testing for all the characteristics. Also you can observe another two substances and their characteristics (Ethanol and Sodium Chloride). In order to see it clearer click once in the image.

                                               Conclusion by Claudia Falcón Morales:

     

REMEMBER!!

REMEMBER, DO NOT POUR THE ORGANIC SOLVENT IN THE SINK! ALWAYS IN THE  SPECIAL CONTAINER!