Katherine Sun CTD Chem Blog

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 ...

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...

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...

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.

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...

Summary/Purpose: In all chemical equations, reactants and products must have an equivalent number of total atoms of each element, which satisfies the Law of Conservation of Mass . In this lab we demonstrate this law by reacting sodium hydrogen carbonate with hydrochloric acid. After which we compared the actual yield of its product, Sodium chloride, to its theoretical yield and found the percent yield. Overall, this experiment predominantly aids in the understanding of mass-mass conversions in chemical equations. Questions 1-4:  The data attained in this lab is: Which reactant is limiting? How do you know? Sodium hydrogen carbonate is the limiting reagent because we had an ample, or excess, amount of hydrochloric acid that we kept introducing to sodium hydrogen carbonate until it was no longer fizzing. Find the theoretical yield of NaCl based on your limiting reactant. To find the theoretical yield of NaCl, you apply the mass to mass relationship between sodium hydrog...

Introduction: In this lab we heated Copper Sulfate hydrate and noted the difference after the water evaporated and left anhydrous salt behind. Copper Sulfate Hydrate before heating: Copper Sulfate Hydrate after heating: Calculations/Lab Questions: 5.  Our high percent error of 19% can be attributed to the inaccuracy of our scale and the misplacement of the plastic bag on the scale.  Folding the bag in such a way that it would fit completely on the scale was difficult, so the mass of the substance and bag may have been skewed. Also, the scale allowed for very little precision since it only measured to one decimal.  Tangentially, I predict that the actual value for the coefficient of water should be higher than what we attained. This is because the true percent composition of water in the  hydrate , 36.0%, is significantly higher than ours. 

Summary/Purpose: The concept of using molar mass to identify compounds and convert units from grams to moles, or vice versa, is rather fundamental in chemistry. In this lab we were asked to identify mystery substances by finding their molar masses. For the A2 bag we identified the substance as Potassium Sulfate and for the B1 bag we identified the substance as Sodium Sulfate. A2 Bag:  We were given the mass of the empty plastic bag and how many moles of the compound was in the bag, but had to weigh the bag on a scale to find it's molar mass. The measurements attained were: To find the molar mass we did the following: Out of the given possible compounds, the compound closest to 190 g/mol is Potassium sulfate , which is 174.26 g/mol. B1 Bag:  We were given the weight of the empty plastic bag and the number of molecules in the bag. Additionally, we had to find the weight of the bag with the substance using a scale. The measurements attained were: ...

Purpose: Predicting chemical equations is a fundamental building block of chemistry; balancing equations and identifying states of matter also contribute physical properties to the equations that are especially beneficial in labs. In this lab we completed seven experiments, each with a chemical reaction that created evidence such as: release of a gas, formation of a precipitate, color change, temperature change, emission or absorption of light. Favorite Experiment: My favorite experiment was when Hydrogen Peroxide decomposed into water and oxygen with the assistance of the catalyst Manganese Dioxide, which essentially lowers the activation energy needed and creates a new path for the reaction. This reaction was specifically special because the wood splint that we lit and blew out would light itself again in the presence of oxygen.

Purpose: When two aqueous solutions are combined together, a precipitate, or solid, is often formed. In this lab we combined pairs of solutions together and evaluated what products were yielded. Additionally, we determined if the products were in a solid or aqueous state using the General Rules for Solubility. Double Replacement Chemical Equations with Ionic Substances:  Net Ionic Equations: Surprise/Challenge: The opaque, vibrant, white color of Silver Chloride surprised me because all other white precipitates were more transparent. The concept of how two seemingly unrelated substances can react to form a completely unique product is shocking.  The most challenging aspect of this lab was determining the solubility of substances after carrying out the double replacement. 

Introduction/Summary: In this lab we reinforced the rules of nomenclature by matching together pieces of a puzzle where each side had either a chemical formula or name written upon it. When all pairs were matched together, the final product was a 4 by 4 square. Biggest Challenge:  Through out the process of assembling the puzzle, the biggest challenge we encountered was finding a good system for effectively putting it together. We realized that it would be extremely tedious to find pieces individually, so we searched for pieces that included the most prevalent elements such as Potassium, Iron, and Barium. Doing so, increased our efficiency significantly, but it was still a challenge to fit all of the collective groups together. Biggest Contribution: Organization was imperative to successfully and effectively putting together the puzzle. Without it, chaos could break out from trying to find a formula/name. It helps to maintain a level-headed disposition when looking at the aby...

Introduction/Purpose: One of the primary values used to identify elements is average atomic mass, which is the weighted average of all isotopes of an element. In this lab, we simulated finding an element's average atomic mass with finding the average weighted mass of three types of candies: Peanut M&Ms, Skittles, and M&Ms.  Our average mass:  The formula for average weighted mass is: The data collected from our sample of candies: Our final average weighted mass of the candies is: Ask a group nearby what their average atomic mass was. Why would your average atomic mass be different than theirs? A neighboring group's average atomic mass was 1.05 g. Our average atomic mass, 1.03 g, and theirs differ because in a random sample, any combination(distribution) of the three candies is possible. Moreover, there is no way to control the manufacturer's distribution and masses of the candies. However, when the sample size is large enough, all ...

Introduction: This report discusses how, through paper chromatography, we created patterns from a variety of black ink pens on circular pieces of paper. More specifically, this examines how ink passed through a medium, in this case, paper, in which its components move at different rates. The objective of this lab is to understand the process of how a mixture is separated and the physical properties that result from it. Why is it important that only the wick and not the filter paper circle be in contact with the water in the cup? If the entire filter paper were to be in contact with the water, there would be no outward radial spread of the pigments due to the lack of an origin from which water spreads. Therefore, the results that show certain pigments at further distances from the origin would be hindered. What are some of the variables that will affect the pattern of colors produced on the filter paper? The brand of marker used, color of marker used, type o...

Purpose: We did this lab to, again, reinforce the relationship between density, mass, and volume. We were given a scale and a ruler and were asked to solve for the thickness, or height, of the aluminum foil. Procedure: To perform the experiment, we found the mass of the foil using the scale (0.7g) and then found the length (11.75 cm) and width (11.72 cm) of the foil using the ruler. After doing so, we set up the following equation and solved for the height:                                      where h=height, m=mass, d=density, w=width, and l=length. Data: As discussed above, the data is:  Conclusions: The challenging part of this lab for me was getting used to significant figures. Other than that, I think the procedure of the lab was quite straight forward and none of the results were quite surprising. 

Introduction: The purpose of the lab was to establish the relationship between mass, volume, and density. It was also to introduce us to using significant figures, using units, and writing lab blogs. To define a few key terms, volume is the physical space an object takes up and mass is the amount of matter something has.  Procedure: We were given a cube with a given density and asked to determine the mass. First, we found the volume of the cube by measuring the sides with a ruler. Then, we used the volume and the density to determine the mass. After finding a mass, we compared it to the actual mass of the cube and calculated the percent error.  Data: The actual mass of the cube was 15.6 g, so our percent error was 2.6%, which is less than 5%. Conclusion: We fulfilled the purpose of this lab by understanding density and how to correctly use significant figures and units. Error could have possibly occurred from incorrect estimations of the dimensions of the cube...