LAB SESSION VISCOSITY

Substance	Time (s)	Time 2 (s)	Average
Propyl acetate	0,48	0,48	0,48
Methyl acetate	0,30	0,34	0,32
Butyl acetate	0,23	0,26	0,25
Ethyl acetate	0,42	0,40	0,41

Substance	Time (s)	Time 2 (s)	Average	Molecular weight
Butanol	0,33	0,31	0,32	74,12
Propionic acid	0,27	0,18	0,23	74,08
n-Pentane	0,21	0,18	0,20	72,15
Diethylether reinst	0,18	0,11	0,15	74,12

Objective:

Relate the intensity of the intermolecular forces to a measurable property. Associate the intensity of the intermolecular forces to structural characteristics of the molecules.

Materials:

·         Group of substances 1 (similar molecular weight): diethyl acetate, pentane, methyl acetate, butanone, butanol, propionic acid.

·         Group of substances 2 (homologous series): methyl acetate, ethyl acetate, propyl acetate, butyl acetate.

·         100 mL measuring cylinder

·         Small spheres of iron or glass

·         Chronometer

Security:

-          Use goggles

-          Diethyl ether is extremely volatile and flammable. Manipulate it always in a ventilated place and away of flames and sparks.

-          All these substances are volatile. Avoid inhalation.

Procedure

1.      Fill the measuring cylinder with 100 mL of one of the substances.

2.      Drop one of the spheres as close to the liquid surface as you can.

3.      Measure the time that the sphere takes between the 10 mL and the 80 mL mark in the tube.

4.      Repeat steps 2 and 3 twice.

5.      Return the liquid of the measuring cylinder into its container and retrieve the balls.

6.      Rinse the measuring cylinder with some acetone and let it dry.

7.      Repeat the whole procedure for the other liquids provided.

8.      Return the liquid of the measuring cylinder into its container and retrieve the balls.

9.      Rinse the measuring cylinder with some acetone and let it dry.

10.  Repeat the whole procedure for the other liquids provided.

Graph:

1. Find out what relationship exists between the drop time and the viscosity. REFERENCE!

On this part of the experiment we have on the same substance two different times because we need to do the experiment 2 times, as it is asked on the handbook, but we can see that the time it is more or less the same. Viscosity is a measure of how well substances flow. So, our conclusion would be if more time is given to a substance to get from the top part to the deep part of the test tube, more viscosity would have. And as we can see on the table, with the substances Butanol and N-Pentane; Butanol, timeà 0.33 & 0.31 and has a viscosity of 74.12. N-Pentane, timeà 0.21 & 0.18 and has a viscosity of 72.15.

Butanol has a higher viscosity because it has been required more amount of time, on the other hand, N-Pentane is the opposite.

2. Find out what relationship exists between viscosity and intermolecular forces.

If we have a substance with stronger intermolecular forces, we obtain a higher viscosity. As an example, we can see this with N-Pentane and Propionic acid, N-Pentane has one intermolecular force (Van der Waal) and Propionic acid has the three intermolecular forces, as a result we obtain that N-Pentane has a viscosity of 72,15 and Propionic acid a viscosity of 74,08. 

3. Find out what intermolecular forces have each substance.

Propyl acetateà Van der Waals and permanent dipole-dipole

Methyl acetateà Van der Waals and hydrogen bonding

Butyl acetateà Van der Waals and permanent dipole-dipole

Ethyl acetateà Van der Waals and permanent dipole-dipole

Butanolà hydrogen bond, dipole-dipole force and Van der Waals

Propionic acidà Van der Waals

N-Pentaneà Van der Waals

Diethylether reinstà Van der Waals and hydrogen bonding

4.      Explain the meaning of your results and write out your conclusion, including if possible, data from the bibliography.

In this experiment we found out what intermolecular forces had some elements, we discovered some interesting results, and our expectations were exactly the same as the results. In exercise number two, we founded out the relation between viscosity and intermolecular forces. The experiment was kind of complicated in the way that it was difficult to record the exact time because the little sphere was very fast at the time to go down the test tube. As we can see, the time-results of the first table are higher than the results on the second table. This could be because the chemicals on the second table are lighter than the chemicals on the first table.

5. Evaluate the procedure in respect to precision and accuracy of the results. Indicate weaknesses and sources of error and improvements for them.

1.      Fill the measuring cylinder with 100 mL of one of the substances: We were very precise and we used a test tube were the 100mL were marked.

2.      Drop one of the spheres as close to the liquid surface as you can: This step was very easy; we just had to drop the little sphere. Maybe we could have tried to be more precise at the time of starting to record the time.

3.      Measure the time that the sphere takes between the 10 mL and the 80 mL mark in the tube: this step was the hardest step, we had to be very precise, and sometimes, we repeated the step several times. To solve this, we might have talk to each other more to be more precise. 

4.      Repeat steps 2 and 3 twice: the same.

5.      Return the liquid of the measuring cylinder into its container and retrieve the balls: clean

6.      Rinse the measuring cylinder with some acetone and let it dry: clean

7.      Repeat the whole procedure for the other liquids provided: the other liquids were the same. We repeated the steps. The problems were the same.

8.      Return the liquid of the measuring cylinder into its container and retrieve the balls: clean

9.      Rinse the measuring cylinder with some acetone and let it dry: clean

10.  Repeat the whole procedure for the other liquids provided: repeat the process. The same problems.

Bibliography:

Rgecchemistryblog.blogspot.com.es,. (2015). Year 10 Chemistry Blog: Vapour Pressure and Intermolecular Forces. Retrieved 24 January 2015, from http://rgecchemistryblog.blogspot.com.es/2014/03/vapour-pressure-and-intermolecular.html

ChemistNATE | Lessons,. (2015). Effects of Intermolecular Forces. Retrieved 24 January 2015, from http://lessons.chemistnate.com/effects-of-intermolecular-forces.html

The properties of substances and their bonding

OBJECTIVE

To study, evaluate and compare the properties of several substances and relate them to their type of bonding (ionic, covalent or metallic).

Theoretical background

The properties of substances are related to the kind of bonding present in those substances. The type of bonding depends on the atoms present and is related to their position in the periodic table.

Materials

Substances A to D                           Conductivity meter

Test tubes                                         Distilled water

Spatula                                             Acetone

Bunsen burner

Method

Repeat the procedure for each of the substances provided:

1.     Take ½ a spatula of the substance in a test tube. Describe the appearance of the substance.

2.     Gently heat it in the flame of the Bunsen burner and state if the approximate melting point. (Low, intermediate or high).

3.     Take ½ a spatula of the substance in another test tube.

4.     Add 10 mL water, stir it and state whether the substance is soluble in water or not.

5.     Repeat the steps 4 and 5 using acetone instead of water.

6.     Using the conductivity meter, state if the substance is a conductor in solid state.

7.     If it the substance is soluble in water, test whether the solution is a conductor or not.

Blog tasks

The whole report must be posted to your group blog. Make sure you include:

Annotations:

1.)   Paraffinà the appearance of this substance is extremely thick granules. Are rounded little white balls. This substance has a low melting point.

2.)   Salt (NaCl)à the appearance of this substance is small, white and thin granules. It has a very high melting point.

3.)   Starchà the appearance of the substance is very small, white and dust-appearance. It has a high melting point; the substance is getting burning and not melted.

4.)   Magnesiumà the appearance of the substance is a small squared piece of metal. It has a very high melting point.

Now we need to do the same step but instead of melting them, we need to see if it is soluble in water.

1.)   Paraffinà it has a low melting point but it is not soluble in water because it is hydrocarbon.

2.)   Saltà it has a high melting point but is soluble in water.

3.)   Starchà it has a high melting point, and it is not soluble in water; the water gets a white colour not transparent.

4.)   Magnesiumà It has a high melting point and it’s not soluble in water.

Now we do the same steps but instead with water with some acetone.

1.)   Paraffinà the paraffin is not soluble in acetone; it gets at the bottom of the test tube.

2.)   Saltà the salt is not soluble in acetone; it gets at the bottom part of the test tube.

3.)   Starchà the starch is not soluble in acetone.

4.)   Magnesiumà this element is not soluble in acetone.

Now we need to see if the substances conduct electricity.

1.)   Paraffinà the paraffin is not a conductor of electricity.

2.)   Saltà the salt is not a conductor of electricity.

3.)   Starchà the starch is not a conductor of electricity.

4.)   Magnesiumà this element is a conductor, it conducts electricity.

1.     A table of results.

SUBSTANCES	SOLUBILITY IN WATER	SOLUBILITY IN ACETONE	MELTING POINT	CONDUCTIVITY OF ELECTRICITY	TYPE OF BONDING
PARAFFIN	NOT SOLUBLE IN WATER	NOT SOLUBLE IN ACETONE	LOW MELTING POINT	NOT A CONDUCTOR OF ELECTRICITY	COVALENT BONDING
SALT	SOLUBLE IN WATER	NOT SOLUBLE IN ACETONE	HIGH MELTING POINT	NOT A CONDUCTOR OF ELECTRICITY	IONIC BONDING
STARCH	NOT SOLUBLE IN WATER	NOT SOLUBLE IN ACETONE	HIGH MELTING POINT	NOT A CONDUCTOR OF ELECTRICITY	IONIC BONDING
MAGNESIUM	NOT SOLUBLE IN WATER	NOT SOLUBLE IN ACETONE	HIGH MELTING POINT	A CONDUCTOR OF ELECTRICITY	METALLIC BONDING

2.     The type of bonding present in each substance.

Paraffin: covalent bonding because covalent bonding requires a low melting point (because I only need enough energy to overcome the weak forces of attraction/ the melting point is low)

Salt: salt is ionic bonding because ionic bonding requires a high meting point (because we need to break all the strong electrostatic attractions. This requires a lot of energy) and does conduct electricity in water.

Starch: As well as salt, it has giant covalent bonding because it has a high meting point.

Magnesium: Metallic bond. The forces of attraction between the metal Cations and the 'sea' of delocalised electrons.

3.     A secondary table to show “expected” results. (Research the type of bondingand the expected results for the test that you carried out)

SUBSTANCES	SOLUBILITY IN WATER	SOLUBILITY IN ACETONE	MELTING POINT	CONDUCTIVITY OF ELECTRICITY	TYPE OF BONDING
PARAFFIN	NON SOLUBLE IN WATER	SOLUBLE IN ACETONE	LOW MELTING POINT	NOT A CONDUCTOR OF ELECTRICITY	COVALENT  BONDING
SALT	SOLUBLE IN WATER	NOT SOLUBLE IN ACETONE	HIGH MELTING POINT	A  CONDUCTOR OF ELECTRICITY IN WATER	IONIC BONDING
STARCH	NOT SOLUBLE IN WATER	SOLUBLE IN ACETONE	HIGH MELTING POINT	NOT A CONDUCTOR OF ELECTRICITY	GIANT  COVALENT BONDING
MAGNESIUM	NOT SOLUBLE IN WATER	NOT SOLUBLE IN ACETONE	VERY HIGH MELTING POINT	A CONDUCTOR OF ELECTRICITY	METALLIC BONDING

4.     A conclusion comparing the actual results with the expected results.

When we start doing the experiment we thought that some of the elements would have more or less melting point, would have more or less electricity… So our results have been the ones that we expected, where we have made an error is in the theme of the conducting electricity, we thought that some of them would conduct but none of them do.

For example: In paraffin, we had that that the substance wasn’t soluble in water or even in acetone, we had too that the substance (paraffin) had a low melting point and it doesn’t conduct electricity, and, our expected results, were slightly different. This is because we expected paraffin to be soluble in acetone, so this way, it could be a perfectly-formed covalent bond.

Now, we’ll get into our next substance, salt .Our results were the following: Salt was soluble in water, not soluble in acetone, it had a high melting point and it doesn’t conduct electricity.

Our expected results were: Salt to be a conductor of electricity just in water, so it could be a perfect giant covalent bonding.

Our next substance is starch: Starch, is a substance that wasn’t soluble in water or even in acetone, it had a high melting point and it wasn’t conductor of electricity.

But our expected results were: starch to be soluble in water so it had ionic bonding.

And our final substance was magnesium: magnesium wasn’t soluble in water, it wasn’t soluble in acetone, it had a high melting point and it was a conductor of electricity. This is the only substance that was exactly the same as our expected results because it’s a metallic bonding.

5.     An evaluation that suggest improvements that could be made to your method.

-We could have been confused putting the results of every substance: so if that happened, we would have a problem because it would be different types of bonding instead of the type of bonding that they really are

-We could make confusion when we were looking at the substance: if it really was melted or not

-The time of seeing at the (for example) the melting point, with the acetone, with the Bunsen burner….: it’s better to be focussed on what we are doing because if not the experiment would be wrong and a completely fail.

-We could have more or less quantity in the volumetric flask than it was necessary

6.     A minimum of 2 references (APA format).

Anon, (2014). [online] Available at: http://www.chemistry.sc.chula.ac.th/bsac/Org%20Chem%20Lab_2012/Exp.1[1].pdf [Accessed 4 Oct. 2014].

Answers.com, (2014). What factors affect the solubility of a particular substance. [online] Available at:http://www.answers.com/Q/What_factors_affect_the_solubility_of_a_particular_substance [Accessed 4 Oct. 2014].