Lab Report 1 : Solubility PDF

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Huynh 1 Tam Huynh Partner: Lindsey Campbell Prof. Dutz CHEM220 February 11, 2020 Lab 1: Solubility report. Part A. Solubility of Solid compound. 1mL of Water Benzophenone Tartaric Acid Naphthalene

Insoluble Soluble Insoluble

1mL of Methanol Soluble Soluble Partially soluble

1mL of hexane

Control

Partially soluble Insoluble Partially soluble

X X X

Discussion part A. First is benzophenone, a pure hydrocarbon, a nonpolar molecule with a polar carbonyl group. Therefore, in water, benzophenone cannot dissolve in water (likes dissolve likes) because water is a polar molecule, while benzophenone is a pure hydrocarbon, which is very insoluble in water, the major of benzophenone is nonpolar. Methanol has an intermediate polarity; however, it can dissolve benzophenone because the polar carbonyl group on benzophenone can make hydrogen bond to the methanol; therefore, making benzophenone soluble in methanol. Last is hexane, a nonpolar molecule; benzophenone is partially soluble in hexane because the major of benzophenone is nonpolar, which is right for “likes dissolve likes”, makes it soluble in hexane. However, the functional group on hexane is polar; therefore, the benzophenone is only partially soluble in hexane. The next compound is tartaric acid, a polar molecule. Therefore, it can easily be soluble in water and methanol (both are polar molecules). But when tartaric acid is added to hexane, it is insoluble because hexane is a nonpolar molecule, which tartaric acid does not want to dissolve in. The last compound is naphthalene, a nonpolar compound. It is insoluble in water because water is a polar molecule. In methanol, because it is slightly polar with the rest is nonpolar, naphthalene is only partially soluble. In hexane, a nonpolar compound, which should make naphthalene soluble; however, naphthalene was observed to be partially soluble, it could occur due to the contamination while dropping hexane in naphthalene solid, or it could be because the dropwise was not done well. There is a difference in the result between the solubilities of naphthalene in methanol (partially soluble) versus benzophenone in methanol (soluble). There is such a difference because benzophenone has a functional carbonyl group that can hydrogen bond with methanol while naphthalene can partially dissolve in methanol because its nonpolar character and the rest of naphthalene cannot because methanol has an intermediate polarity; therefore, only benzophenone can be soluble in methanol while naphthalene is partially soluble. There is also a difference in the result between the solubilities of benzophenone in methanol (soluble) versus benzophenone in hexane (partially soluble). As mentioned above, methanol can form a hydrogen bond with benzophenone because of the carbonyl group on benzophenone, so those two can dissolve in each other. Between benzophenone and hexane, benzophenone is a major nonpolar group with a minor polar functional group, and hexane is a nonpolar molecule; therefore, benzophenone can only be partially soluble in hexane. Part B. Miscibility of different alcohols.

Huynh 2

Water Hexane

1-octanol Immiscible Miscible

Methanol Miscible Immiscible

1-butanol Miscible Miscible

Discussion part B. Water is a polar molecule, and it can form a hydrogen bond with alcohol. In methanol, water is completely miscible; it can be observed as one clear layer. In 1-butanol, it was noted with tiny horizontal lines. However, it was still miscible with 1-butanol, because although butanol is a nonpolar with a polar hydroxyl group can form a hydrogen bond with water, the polar group is still a significant property that made up 1-butanol character. However, in 1octanol, the major of it is nonpolar with the hydroxyl group is polar; therefore, when mixing water (a polar molecule) with 1-octanol, they are immiscible. Hexane is a nonpolar molecule. When it was mixed with 1-octanol, the major of octanol is a straight chain of carbon, which makes 1-octanol nonpolar; therefore, 1-octanol and hexane are miscible. When hexane is mixed with methanol, they are immiscible because methanol is a polar molecule based on its function alcohol group. When hexane is mixed with 1-butanol, it is miscible because 1-butanol has a straight chain of carbon, which is suited with hexane as a solvent; therefore, they are miscible. Part C. Miscible or Immiscible pair.

Ethanol Diethyl ether Dichloromethane Hexane

Water Miscible Immiscible Immiscible Immiscible

Hexane X X Miscible X

Discussion part C. For the pair between water and ethanol, both water and ethanol can form hydrogen bonding, that is why they are miscible. For the couple between diethyl ether and water, because diethyl ether is a nonpolar molecule and water is a polar molecule with hydrogen bonding molecule, diethyl ether cannot dissolve in water; therefore, the mixture formed two layers, which indicates that they are immiscible pair. Dichloromethane and water were reported to be immiscible because dichloromethane is a nonpolar molecule, and water is a polar molecule, the halogen chlorine that attached to the structure of dichloromethane did not significantly help in improving its polarity; therefore, dichloromethane and water cannot dissolve in each other. However, hexane is a nonpolar molecule, with dichloromethane (also nonpolar molecule), base on “likes dissolve likes”, they can dissolve in each other; therefore, they are miscible. For water and hexane, water is a polar molecule, and hexane is a nonpolar molecule, they cannot dissolve, so they are immiscible. Part D. Solubility of organic acids and bases.

Benzoic acid, 30mg

Water Insoluble

1.0M NaOH Soluble Insoluble

1.0M HCl Insoluble 6M HCl dropwise after

Huynh 3 first mix

Ethyl 4aminobenzoate

Water Insoluble

1.0M NaOH Insoluble

1.0M HCl Soluble Insoluble

6M NaOH dropwise after first mix

Discussion part D. First when 1.0M NaOH was added to benzoic acid, the mixture was soluble. Because benzoic acid has the functional group carboxyl that can react with NaOH as an acid – base reaction, therefore, they reacted with each other and create a water-soluble benzoate.

When 6.0M HCl was added to this same tube until litmus red, which means the goal of this experiment is to bring the pH of the mixture close to 1 since HCl is a strong acid. Therefore, acidification of the benzoate anion will form neutral benzoic acid, which is insoluble in water and precipitates out of solution as a white solid.

For the tube in which 1.0M HCl was added to ethyl 4-aminobenzoate, they reacted with each other creates a water-soluble salt (reaction between strong acid and base).

When 6.0M NaOH was added to this same tube, this salt was converted back to the original ethyl 4-aminobenzoate because of the high pH that NaOH had changed.

POST-LAB QUESTION 1. a. Between the pair of butanoic and water, butanoic acid will be dissolved in water because it has the functional carboxyl group that very polar, which makes it dissolve easily in water (polar molecule) based on “likes dissolve likes”. Moreover, the butanoic has a lone pair on the oxygen atom that acts as a hydrogen bond acceptor, which makes it more soluble in water. b. Between the pair of aspirin and NaOH, aspirin is soluble in NaOH. Because aspirin contains the carboxyl functional group that acts as an acid, NaOH is a strong base; these two can react with each other as an acid-base reaction. Therefore, aspirin can be dissolved in NaOH.

Huynh 4 c. Between the pair of amphetamine and water, amphetamine may soluble in water because it has an amine group which can form hydrogen bonding with water. Therefore, amphetamine can dissolve in water. 2. a. 1- butanol and isopropyl alcohol would be miscible since they can make hydrogen bond to each other; therefore, they can dissolve in each other and create a one-layer mixture. b. Water and toluene would be immiscible because toluene is a nonpolar molecule, and water is a polar molecule, which indicates that they cannot dissolve in each other. Therefore, they will create a two-layer mixture, and they are immiscible. c. Hexane and toluene will be miscible since hexane is a nonpolar molecule, and toluene is also a nonpolar molecule. Based on “likes dissolve likes”, they will dissolve in each other and create a one-layer mixture, which indicates they are miscible. 3. Although cannabinol and methyl alcohol are both alcohols, cannabinol is only slightly soluble in methyl alcohol at room temperature because methyl alcohol has a very short chain of carbon while cannabinol is a pure hydrocarbon with a hydroxyl functional group. Although both of them can create hydrogen bonding, cannabinol is considered more likely to be a nonpolar molecule, the functional group on cannabinol does not have significant effects on its polarity; however, the functional polar group on methanol will create a substantial effect on its polarity, it makes methanol becomes a polar molecule. Therefore, based on “likes dissolve likes”, methanol and cannabinol cannot dissolve in each other. References Speakman, Teresa J. A Laboratory Manual for Student at Golden West College. May 2019. Mohrig, Jerry R. Laboratory Techniques in Organic Chemistry, 4th ed....