Katherine Sun CTD Chem Blog

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Lab 18: Alka Seltzer and the Ideal Gas Law

August 01, 2017

Introduction: Alka Seltzer tablets contain sodium bicarbonate and citric acid, which when dropped in water, dissolve and react to produce carbon dioxide gas. In this lab we dropped 2 Alka Seltzer tablets into a test tube filled with water and then wrapped a balloon around its rim. When the Alka Seltzer stopped fizzing, we measured the circumference that the balloon blew up to. Furthermore, using the ideal gas law, we determined the mass of the carbon dioxide gas produced. after Alka Seltzer was dropped into the test tube Data Table: Calculations: Analysis Questions Discuss an area in this lab where experimental error may have occurred. When we were transferring the ground Alka Seltzer tablets from the plastic tray to the balloon, we inevitably lost some of it and could not remeasure how many grams of the alka seltzer tablet remained. Another source of experimental error was our inability to measure the circumference of the balloon per...

Lab 16: Specific Heat of a Metal

July 31, 2017

Introduction: Different substances require distinct amounts of energy/heat to produce equivalent changes in temperature. Specific heat is the amount of energy required to raise one gram of a substance one degree celsius higher. In this lab, we identified an unknown metal by following a procedure that allowed us to determine its specific heat. Data: We attained the following measurements: Calculations: Finding the specific heat, c , is a two-step process where first you must find the heat gained by the water and then use its equivalent, the heat lost by the metal. The heat gained by the water is: . Since the heat lost by the metal is equivalent to the heat gained by the water, the metal lost 2060 joules of heat. We can use this value of - 2060 Joules in our second step of calculating the specific heat. Thus, we have, . Now, we can look at the list of metals and identify the metal as Brass because it had the nearest specific ...

Lab 15: Evaporation and Intermolecular Attractions

July 30, 2017

Pre-Lab: Data Table: Analysis Questions: Explain the differences in the difference in temperature of these substances as they evaporated. Explain your results in terms of intermolecular force. With the exception of glycerin, all of the final temperatures were less in value than the initial temperatures of their respective substances. Some substances, like methanol, had weaker intermolecular forces, which resulted in higher volatility and a larger decrease in temperature. Contrastingly, glycerin's temperature increased through out the four minutes due to its three extremely strong OH bonds. Explain the difference in evaporation of any two compounds that have similar molar masses. Explain your results in terms of intermolecular forces. Methanol and ethanol are two compounds that have similar molar masses, 32.04 g/mol and 46.08 g/mol, but methanol decreased four more degrees celsius than ethanol did. This is because methanol's intermolecular forces are weaker t...

Lab 14: Create a Smell Lab: Ester Synthesis

July 27, 2017

Introduction/Purpose: Scientists in the lab often try to produce specific compounds through a process called synthesis . In synthesis, chemists produce a chemical compound from two simpler compounds. For our lab, we combined different acids with alcohol to synthesize three esters with various smells and analyze the products of this chemical change. Tubes After Heating: Data: Analysis Questions: Compare the odors of the three mixtures after heating compared to the odors of the starting materials. How are they different? Before heating, two of the three mixtures, with isopenthyl and ethyl alcohol, smelled rather pungent, like vinegar. However, after heating, the putrid smells of these two mixtures became much more pleasant and familiar. The strength of the scent sometimes became stronger after heating; we could actually pinpoint the scent methyl alcohol solution after heating it. Based on the smell of the mixtures after heating, what functional group must...

Lab 12: Electron Configuration Battleship

July 26, 2017

Biggest Challenge: The biggest challenge of this game was being strategic about where to guess your hits and being careful to waste any guesses on useless locations. Once you obtain a hit, sinking the rest of the ship becomes rather easy, as there are only a few possibilities. Otherwise, naming the electron configurations almost became second nature as the game progressed. Learning Experience: This game reinforced the process of naming the f block in the electron configuration whenever guessing an element with more than 57 protons. Before, I was constantly forgetting to write 4f^10 or 5f^10 when writing the configuration for an element with more protons, but now I feel as though I remember it well.

Lab 11: Flame Test Lab

July 25, 2017

Summary/Introduction: When atoms are heated to high temperatures, some electrons may absorb energy and jump from ground state , the most stable energy state, to higher energy levels, where the element is then said to be in an excited state. As the electrons "fall back" to their ground state after being in an excited state, the energy that was absorbed is released as electromagnetic radiation, some of which is in the form of visible light. In this lab, the flame colors exhibited from different metallic ions are the emitted photons of visible light that were vaporized by burner. Furthermore, different metallic ions release waves of different wavelengths, which correspond to contrasting colors. Thus, by observing the color of a flame, the unknown ions can often be identified. Pre Lab Questions: What is the difference between ground state and an excited state? Ground state is where electrons of an atom are in their normal configurations and are in their most stable energ...

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