Lab 1-4 - lab report PDF

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Title: Lab #1 Intermolecular forces overview

Objective: The purpose of this experiment is the determine intermolecular forces of various substance, in comparison to each other. Data and Results: The experiment was conducted into two parts: table 1.1 (listed below) includes data collected for part A of the experiment, and table 1.2 (listed below) includes data collected for part b of the experiment. In part A, three different pipettes were used to produce approximately 3 cm high drop of acetone, alcohol, and water, visual observation was used to see the order in which the liquid evaporated from table surface. Data for part A is recorded in table 1.1, and evaporation order is ranked from 1 to 3, as the number 1 is given to the fastest substance disappearing from table surface, and the number 3 is assigned to the last substance remaining on the able. Part B of the experiment included taking clean penny and carefully placing drops of various substances (liquid soap mix, water, isopropanol, acetone) one at a time on a penny until substance spilled over, and recording number of drops for each substance. Table 1.2 displays the number for drops held by the penny in three different trials, and last column shows the average of each trial. Table 1.1: Part A Data: Evaporation rate Substanc Evaporation order: Rate e Acetone 1 Fastest Alcohol 2 Medium Water 3 Slowest Table 1.2: Part B data: Number of drops of various substance contained on a single penny Substance Number of Drops Average # of drops Trial 1 Trial 2 Trial 3 Liquid soap 13 11 12 12 Water 27 26 28 27 Isopropanol 26 24 22 24 Acetone 19 17 18 18 Conclusion: In part A, while comparing the evaporation rate of acetone, alcohol, and water, table 1.1 indicates acetone being the first liquid to evaporate, then alcohol, and lastly water. As water is the last to evaporate indicates the substance to have the strongest intermolecular force, while acetone having the weakest intermolecular force as compared to alcohol and water as it was the fastest liquid to evaporate Part B of the experiment indicates liquid soap to have the least amount of intermolecular force or cohesiveness that help the liquid soap molecules stay together before spillage occurred, while water had the strongest intermolecular force as most amount of drops were contained on the penny before spillage occurred. The surface tension for liquid saop is much lower than the other three substance, and this is evidenced by the lowest amount of droplets of liquid saop, in comparison of the other three. Ranking the substance in table 1.2 with the strongest to weakest intermolecular force would occur as follows: water, isopropanol,

acetone, and liquid soap mixture. Because water is a polar molecule, there is stronger bond between the hydrogen, thus creating a stronger surface tension, yielding for strongest surface for water droplets to rest upon. By adding liquid soap to the water substance, the intermolecular force was compromised, thus yielding the lowest number of liquid droplets being contained on penny. Comparing part a and b, both experiment support water having the strongest intermolecular force. The experiment could be proven upon by using a precision tool that ensures accurate amount of droplets were being dispensed, thus reducing operator error in dispensing the liquid on to the penny. Connection to theory: 1.3: Data collection comparison from table 1.1 and 1.2 Substanc Evaporatio Rate Avg number e n order: drops on penny Acetone 1 Fastest 18 Alcohol 2 Medium 24 Water

3

Slowest

27

Intermolecular force (IMF type: LDF, dipole LDF, dipole-dipole, hydrogen bond LDF, Dipole-dipole, polar

Strength IMF weakest medium strongest

As noted in table 1.3, acetone, alcohol, and water are ranked on their intermolecular force strength. Figures below show the intermolecular between the atoms present in water, acetone, and alcohol.

Title: Lab #2: Unknown Solid Objective: The purpose of melting point experiment is uncover the identity of two unknown liquid samples by using melting point apparatus, and observing the degree (Celsius) in which the solid powder turns in to liquid. Data/Results: Table 2.1: Melting point data control and unknowns samples Trial 1-heating rate-5°C Trial 2-heating rate-2°C Substance Melting point range Substance Melting point range Naphthalene 81.8°C -84.8°C Naphthalen 80.8°C -81.6°C e Unknown B 53.0°C -58.2°C Unknown B 53.5°C -54.5°C Unknown G 132.0°C -134.6°C Unknown G 132°C -133.4°C Initially approximate 0.5 grams of Napthalene, approximate 0.5 grams unknown b sample, and approximate 0.5 grams unknown G was grinded in separate containers to fine powder in the safety hood. Using capillary tubes, each sample was collected and labeled and placed in the melting apparatus, and two trials were conducted. During the first trial, the melting apparatus heating range was set at 5 °C, starting temperature was set at 45 °C and ending temperature was set at 220 °C. Table 2.1 shows melting point range from trial 1 and melting point range for trial 2 which was set slower incremental heat rate at 2°C and starting temperature of 75 °C and ending temperature of 175°C. This range was set after results trial 1 collected. Conclusion: Using the data from table 2.1 melting point range data from trial 2 and the given melting point of known compound from lab manual page 17, it can be concluded sample B has melting point range of 53.5°C-54.5°C which is close to the melting point of maleic anhydride whose known range is 52 °C-54°C. While sample unknown G has melting point range of 132°C -133.4°C which is close to compound urea whose known melting point is 132.5°C-133.0°C. Naphthalene which is also the control was observed to have melting point of 80.8°C-81.6°C which is close to its given melting point which is 80.0°C-82.0°C. By setting two different heating rates in trial one and trial two, this allowed a closer range on melting point range, which allowed for more precise range. Even though the ranges collected in trial one and trial two are not precise, but they can be considered accurate, as they are near each other. Trial two’s data ranges allows for a more precise range as a lower heat increase rate is used. Class connection: As discussed in class, the stronger the intermolecular force and the more symmetrical compound the higher the melting point of a substance. Hydrogen bond, dipoledipole and London dispersion force are the type of bond a molecule can have. Hydrogen bond are the strongest and thus have the highest intermolecular force and have the highest melting

point, while London dispersion force have the lower intermolecular force holding them other thus are the easiest bonds to break apart, thus have the lower melting point. Unknown B: maleic anhydride has a melting point of 52°C-54°C which is relatively low compared to naphthalene and urea. As listed below this could be attributed to the compound not having any hydrogen bonds, and only containing dipole-dipole and London dispersion forces. Also the structure is not a symmetrical compound, thus the leading to lower melting point. Unknown G: urea has a melting point of 132.5°C-133.0°C. This relatively high compared to control. As noted below urea contains hydrogen bonds between nitrogen atom, and is relatively more symmetrical.

Title: Lab #4: Properties of Hydrocarbons

Objective: The purpose of this experiment is to identify the hydrocarbon of an unknown sample by conduction 4 different experiments. Part A of the experiment will deal with finding out if unknown sample B is soluble or insoluble in polar (water) and (nonpolar) substance. Part B will take the unknown B sample and test is volatility against two controls hexane and octane under a controlled hooded environment. Part C of the experiment involves using process of bromation and UV light and expositing it with unknown sample to see if a change is note. Part D involves using KMnO4 to test if oxidation occurs in unknown sample, cyclohexane, and cyclohexen. Data/Results: Table 3.1: Part A: Solubility test Compound Unknown B Unknown B (2 mL)+ water (1 mL) Unknown B (2 mL) + toluene (1 mL) Controls: Acetone (2 mL) + water (1 mL) Acetone (2 mL) + toluene (1 mL) Hexane (2 mL) + water (1 mL)

Observations

Conclusions (soluble or insoluble)

clear with line Clear

Insoluble Soluble

Light yellow/clear soluble Light yellow/clear soluble Clear separation, water insoluble bottom Hexane (2 mL) +toluene (1 mL) Clear soluble Part A Data/Results: As noted in table 3.1 unknown B is dissolved in toluene which is a nonpolar molecule yielded a soluble mixture. While unknown B when mixed with water which is a polar compound yielded in insoluble mixture. A control experiment was set up as well. Acetone which has both polar and nonpolar bond was mixed in water and toluene, which yielded a soluble mixture in both solutions. While Hexane which only contains hydrogen and carbon bonds was mixed in polar molecule of water yeiled clear insoluble substance, and soluble substance when mixed with toluene which is nonpolar molecule. Table 3.2: Part B: Evaporation Data Compound Time (seconds)

Ranking of evaporation (1= fastest, 3=slowest) Unknown B 53 seconds Medium (2) Control: Octane 131 seconds Slowest (3) Control: hexane 32 seconds Fastest (1) Part B Data/Results: Using a pipet one drop of sample of unknown B, octane, and hexane are dropped under hood and stop watch is used to test how fast each substance evaporates. Results are noted in table 3.2. The first molecule to evaporate the fastest is hexane at 32 seconds, then unknown sample B at 53 seconds, and lastly the slowest one disappear is octane at 131 seconds. Table 3.3: Part C: Bromination Test Compound Observations Conclusion Observations Conclusion after Addition of (positive or after Addition of (positive or Br2 negative) UV light negative) Unknown B Orangeish clear/ Negative Change of color positive

no change Positive Control (without light) cyclohexene Positive Control (with light) cyclohexane Negative Control With light Cyclohexane

from clear to light yellow Orange to clear

Color changed to clear

Positive

Positive

Orange-no change

Negative

Color change orange to clear

Positive

Orange-no change

Negative

No change in color

negative

Part C: the bromanation test results are shown in table 3.3 and show that 2 unknown sample has no change when bromide is added, but with the unknown sample is exposed to UV light then color change from clear to yellow is observed indicating it to be positive result. Table 3.4: Part D: KMnO4 (Oxidation) Test Compounds Observations after addition of Conclusions KMnO4 Unknown B Positive (cyclohexene) Negative (cyclohexane) Part D: Data/Result:

Purple mixed no change Brown precipitation No color change noted, purple

Negative reaction Positive reaction Negative reaction

Conclusion: ●

Summarize your results- all your results from all four parts.

● Interpret your results: When you compare your unknown to the other compounds tested, what can you conclude about your unknown? ● Evaluate your results: were the results of the unknown tests consistent with each other? If not, why not?

Class connection: Explain the results of the solubility and volatility tests for hexane and octane. Your explanation should include fully labeled pictures with appropriate intermolecular forces. Also show the reactions, reactants and products, for the bromination and oxidation of hexane, cyclohexene and toluene....