p. 1 Megan Ly Chemistry 231L February 20, 2013
SOLUBILITY
Purpose: To better comprehend solubility behavior by investigating the solubility of various substances in different solvents, looking at miscible and immiscible pairs of liquids, and observing the solubility of organic acids and bases. Reference: Pavia, A Small Scale Approach to Organic Laboratory Techniques pp. 6-‐9 Report: Part A 1) Results in table form Solvent:
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Methyl alcohol is more polar than the other two alcohols because of the shorter carbon chain and polar hydroxyl group. For this reason, methanol is soluble in water.
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1-‐octanol and 1-‐butanol are both nonpolar molecules which explains why it is soluble in hexane. Methanol is semi-‐polar and not soluble in nonpolar hexane, even though the small bubbles indicate that solution is taking place.
Part C 1) Results in table form Compound Water & Ethyl Alcohol O H O H O H O H H
&
H
&
Cl Cl H & O H & OH
Miscible/Immiscible Miscible
Water & Diethyl
Ionic compounds are soluble in water to a certain point depending on the compound. The level of solubility changes among different compounds. Some ionic compounds can completely dissolve in water and appear to be a homogeneous mixture. Although, some ionic compounds dissolve very little, and could be considered insoluble, since it does not dissolve fully. Depending on the compound, the level of solubility can be high or low. However, ionic compounds could dissolve to a certain degree. If the solution appears to be a heterogeneous mixture, many may assume through visual representation that it may be insoluble. As stated previously, the smallest amount of solubility should be considered. To confirm whether or not the substance is soluble, observe the efficiency when conducting electricity. Due to practical reasons, the slightest solubility could be considered insoluble by people.
B. Claim: As we go from methanol ethanol 1-propanol 1-butanol the dispersion forces increase.
6. The solubility of the solids were tested using a micro tray, by placing them in water and oil to observe their polarity,
8. ISBN: 0-558-05245-2 Virtual ChemLab: General Chemistry, Student Lab Manual/Workbook, V. 2.5, Third Edition, by Brian F. Woodfield and
By identifying the solubility of the unknown, it could lead to a closer interpretation as to what the functional group the unknown may be. Solubility is determined based on intermolecular attractive forces, such as hydrogen bonding, dipole-dipole, and London dispersion forces. Intermolecular attractive forces arise due to different electron environments in different molecules. For example, water molecules are good at dissolving
Substance A and B were weighed; Substance A weighed 0.502 g and substance B weighed 0.503 g. Both substances were put into two different test tube with approximately 8 ml of DI water into the test tub. Substance A and B were stirred and B dissolved while A did not. This shows that B is soluble in water compared to A. Thus, shows that B is soluble in water than A. The reason why B is soluble in water is because it has a higher dipole moment than A. With a higher dipole moment, it shows that it is soluble in water since it is polar and the bonds were easily broken.
Of the alcohols tested 1-Butanol was found to contain the strongest intermolecular forces (IMF) of attraction, with Methanol containing the weakest. It was discovered through experimentation that Methanol induced the highest ?T of all alcohols tested, and that conversely 1-Butanol induced the lowest ?T. The atomic structure of all four alcohols is very similar, as starting with 1-Butanol a CH2 group is lost as you move from 1-Butanol to 1-Propanol to Ethanol and then again to Methanol. Each structure is fairly linear and contains an H-bond with Oxygen, so the real change is found in the loss of the CH2 group, this lowers the liquid’s Molecular Mass, thus lowering the London forces as you move from 1-Butanol through
Solubility – Very soluble (water), Freely soluble (methylene chloride, chloroform, alcohol), Slightly soluble (acetone) and Insoluble (ether).6 Melting point - 120°C or 248°F.5
4. Write a structural diagram equation to represent the reaction between each alcohol and HCl(aq).
In this experiment, 0.31 g (2.87 mmol) of 2-methylphenol was suspended in a 10 mL Erlenmeyer flask along with 1 mL of water and a stir bar. The flask was clamped onto a hotplate/stirrer and turned on so that the stir bar would turn freely. Based on the amount of 2-methylphenol, 0.957 mL (0.00287 mmol) NaOH was calculated and collected in a syringe. The NaOH was then added to the 2-methylphenol solution and allowed to mix completely. In another 10 mL Erlenmeyer flask, 0.34 g (2.92 mmol) of sodium chloroacetate was calculated based on the amount of 2-methylphenol and placed into the flask along with 1 mL of water. The sodium chloroacetate solution was mixed until dissolved. The sodium chloroacetate solution was poured into the 2-methylphenol and NaOH solution after it was fully dissolved using a microscale funnel.
Take two test tubes, label each test tube according to solvent. Add 1 mL of distilled deionized water to the first test tube and 1 mL of ethanol to the second test tube. Next, add 1 mL of the unknown liquid to each test tube, shake for a small period of time, and observe patiently. During this observation, you will be able to determine whether the two liquids mix completely, slightly, or not at all. If the two liquids mix completely, then you should be able to see one liquid mixed together without a visible line indicating two different substances. This means the two liquids are considered soluble. If the two liquids
Solute – A solute is the material (solid, liquid or gas) that is dissolved in the solvent to create the solution.
Benzophenone was soluble in methyl alcohol whiles biphenyl was partially soluble. Benzophenone and biphenyl are both nonpolar molecules. Methanol is intermediately polar, allowing both nonpolar molecules to be dissolved as it is not too polar or nonpolar. However, biphenyl is less polar than benzophenone. Since methyl alcohol is somewhat polar, the more polar benzophenone is more soluble in methyl alcohol than biphenyl. Also, benzophenone can make hydrogen bonds. Thus, benzophenone is more soluble in methyl alcohol than
As mentioned in the discussion, olive oil, vegetable oil, crisco, and lard were soluble in nonpolar solvents and insoluble in polar solvents. This is due to the chemical composition of polar and nonpolar substances which results from the molecular shape as well as properties of dissolving solutes in solution. Polar substances are hydrophilic and contain polar Van Der Waals interactions (intermolecular forces) such as dipole-dipole forces, ion-dipole forces, and hydrogen bonding. Nonpolar substances are hydrophobic and contain non-polar Van Der Waals interactions. ‘Like dissolve like’ is the reason only polar solutes dissolve in polar solvents and why nonpolar solutes dissolve in nonpolar solvents. Molecules with similar polarity have similar intermolecular forces and therefore, can interact with each, or in this case dissolve9. Additionally, the solubility of a compound is determined by the length of the hydrocarbon chain. Long hydrocarbon chains such as the one found in oleic acid makes a compound more insoluble10. Therefore, since the lipids used in this experiment were hydrophobic substances and each lipid has long hydrocarbon chains, the results were consistent with the scientific literature and principles.
The purpose of this lab was to study colligative properties. These properties are properties that are affected when a solute is added to a solvent. Thus, the amount is important, not the actual type of substance, for the colligative properties. A couple types of this property are the freezing point and boiling point of a substance. (1)