Experiment-No-7-Activity-INDVERTBFDVBs kisbidbisnbohndbeikhyejkdshjsbsdoicbsdidbhdidbshbsuabdsoihdbdigdfjhhasnoujsbhgsnjgc ojmosoo jnsghiusdbkssadhdbdidbdocknsa- IntermGRP3- Gutierrez, Crisha Andrea M PDF

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Gutierrez, Crisha Andrea M. BS PSYCHOLOGYCAS- 06 -102P GROUP 3Experiment No. 7Intermolecular Forces of AttractionINTRODUCTIONAn intermolecular force is the force that mediates interaction between molecules, including the electromagnetic forces of attraction or repulsion which act between atoms and o...

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Gutierrez, Crisha Andrea M.

BS PSYCHOLOGY

CAS-06-102P

GROUP 3 Experiment No. 7 Intermolecular Forces of Attraction

INTRODUCTION An intermolecular force is the force that mediates interaction between molecules, including the electromagnetic forces of attraction or repulsion which act between atoms and other types of neighboring particles, e.g. atoms or ions. There are three types of intermolecular forces: London dispersion forces (LDF), dipole- dipole interactions, and hydrogen bonding. Molecules can have any mix of these three kinds of intermolecular forces, but all substances at least have LDF. The stronger the intermolecular forces of attraction, the more energy is required to break those forces. This translates into ionic and polar covalent compounds having higher boiling and melting points, higher enthalpy of fusion, and higher enthalpy of vaporization than covalent compounds. The properties of matter depend on the intermolecular forces between the particles the matter is composed of. London Dispersion Forces are attractive forces that exist between all atoms and molecules. Dipole Forces result from attraction between the positive and negative ends of molecules with permanent dipoles List of Apparatus

Chemical Reagents

4 small empty bottles

Water

Stirring rod

Rubbing alcohol

Plastic comb

Kerosene

Wax paper or any glossy paper

Detergent Solution

Dropper PROCEDURES Comparison of Liquids A. Reaction of test liquids to charged objects 1. Prepare the chemical reagents-water, rubbing alcohol and kerosene 2. Place water on a medicine dropper. 3. Charged the comb by running it through your hair 20-30seconds. 4. Let the water flows from the medicine dropper and simultaneously place the charged comb in the flowing water. Observe. (See figure) 5. Repeat steps 2-4, but this time using rubbing alcohol and then followed by kerosene.

B. Surface Tension 1. Cut a small piece of wax paper (5 inch by 5 inch). Make 3 pieces. 2. Pour a small amount on the 1 wax paper. Observe st

3. Repeat step 2 this time using rubbing alcohol and kerosene. C. Blade Test 1. Prepare 3 small bottles or any containers. 2. In each container, place a small amount of water, detergent solution and kerosene. 3. Place the blade in each container. Observe. ANALYSIS 1. Comparison of Liquids Observation  Water - The water is drawn towards the charged comb and continuously flows into the charged comb. Rubbing Alcohol - Alcohol is similar to water, it flows fluidly and is attracted to the charged comb. However, some of the alcohol lingers in the charged comb. Kerosene - Kerosene gets caught up in the charge comb without any continuous flow. Explanation  Alcohol is more viscous than water, while kerosene is more viscous than water. A charged comb has negatively charged electrons, so because of the attraction of the electrons of the water and the charged comb, it lets the water bend towards the charged comb and flow continuously. As rubbing alcohol is partly negative charged, just like water it flows constantly in the charged comb. Unlike the water and rubbing alcohol, kerosene did not flow continuously or constantly in the charged comb. In contrast to the two liquids use, it was stuck in the charged comb. 2. Surface Tension Observation  Based on my observation, the water doesn’t spread easily on the wax paper. It just stayed on top of it. It looks like that the drop on the wax paper looks kind of like there’s a skin around it. The drop of water stick to each other. That’s why the surface of the water drops appear to have a skin-like layer on them. While, the rubbing alcohol can be seen, at least, and it will appear as a flat, gray smudge, a little

transparent. After a while, the alcohol will be either sunken into the wax paper or dried out by evaporation. The wax paper is unaffected though, except for traces of the smell of alcohol. On the other hand, kerosene was easily absorbed by the wax paper.

Explanation

 Wax paper has non-polar coating so when polar liquids are pour to wax papers they dissolve, and polar liquids are just still on wax paper compared to non-polar liquids. They dissolve and they just slip through the wax paper. It is also assumes the different shapes on the surface of the wax paper because of the difference of its absorbance property. 3. Blade Test Observation  The blade only stays in the surface of water if you place the blade with a small amount of force. The blade in detergent solution has a delay before it completely falls down. Meanwhile, the blade in kerosene quickly reaches the bottom of the container.

Explanation  Water or H2O has more attractive molecules than detergent solution and kerosene. The water molecules that were attracted to each other form hydrogen bond, this process is called cohesion. Water molecules that bonded together, push together until it is nowhere to go, and pushes the force up to the surface that creates surface tension. It holds responsible for the surface tension happened between water and the blade.

APPLICATION 1. Arrange the following forces in the order of the strongest to the weakest type of intermolecular forces of attraction: London Forces, Ion-Dipole, Dipole-Dipole, and Hydrogen Bonding. Explain your answer.  In order from strongest to weakest, the intermolecular forces are: ion-dipole, hydrogen bonding, dipole-dipole, and London forces. Ion dipole is the strongest because the strength of the ion-dipole force is proportionate to ion charge. Ion dipole attractions become stronger as either the charge on the ion increases, or as the magnitude of the dipole of the polar molecule increases. The London dispersion force is the weakest intermolecular force. It is the weak intermolecular

force that results from the motion of electrons that creates temporary dipoles in molecules. 2. Identify the type of intermolecular forces that exist in each of the following substance:  2.1 CH OCH - London Dispersion Forces and Dipole-Dipole Interaction 2.2 CH O - Hydrogen Bonding, Dipole-Dipole Interaction, and London Dispersion Forces 2.3 CO - London Dispersion Forces 3

3

3

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3. Describe the effects of the intermolecular forces of attraction on the properties of the substance.  CH3OH- Methanol has a Hydrogen bonding, dipole-dipole and London Dispersion. These are the intermolecular forces of attraction present in Methanol. The dipole dipole occurs in Methanol because it create dipole moment between molecules due to the presence of the electronegative oxygen atom. It create permanent dipole within each of the methanol molecules with opposing charge. And that is the dipole-dipole interactions. It also have a Hydrogen Bonding this is a huge difference in their boiling points. It happens when Hydrogen is attached to an atom that is much more electronegative than the hydrogen. And last it also has a higher vapor pressure. CO2 - Carbon Dioxide- it is a colorless and odorless gas and slightly toxic and has a denser than air. It has a London Dispersion Forces it depend on the atomic or molecular weight of the material. Heavier atom or molecules have more electrons and stronger London Forces. This means that they are harder to melt or boil.

CONCLUSION  In conclusion, surface tension is the property of the surface of a liquid that allows it to resist an external force. Clearly shown by the experiment, the cohesive forces between liquid molecules are responsible for this phenomenon, and among the three chemical reagents, water has the highest surface tension. The physical properties of biological substances depend on the intermolecular forces present. The sequence of strength from strongest to weakest force is ions > hydrogen bonding > dipole-dipole > London forces. As the strength of forces decreases, so do the melting points, boiling points, and solubility in water. Besides that, the vapor pressure and the solubility in nonpolar solvents also increase....