Great Work In Lab Report Writing

This section of the website will focus on particularly good introductions and/or conclusions to lab reports. I have asked certain students to email me their work to have you read it, and learn what you should be aiming at. These are some of the best in all four classes. I will add more as the school year progresses. Your comments can be emailed to me, and I will post them up as well. If you do email, indicate which introduction or conclusion you are commenting on. They are numbered for this convenience. I have left off the names of the students but they know who they are and they should be proud of their efforts.

Measurement Lab conclusion

This lab challenged our measuring skills, our use of the S table and, the math and formulas of density and percent error. The class was instructed to measure the volume, the mass, calculate the percent error of various objects such as a textbook, the lab table, our agendas and four very different metals. I learned to measure various objects not with just the ruler but, with water using a graduated cylinder. Another thing I learned is the formula of density and percent error and how to use them. The point of this lab was to have us learn to measure and calculate certain items using formulas and instruments.

Density by Displacement Lab - pennies

Objective - to find the difference in old (1982 and before) and new (1983 and after) pennies by measuring their densities. After determining the pennies' densities, we will determine what type of metal is used to produce the new pennies.

Conclusion - In this lab I learned how to measure the density of old pennies and new pennies by using their mass and their volume (the volume measured through displacement). I learned that pennies before 1983 are pure copper and pennies made after 1983 only have a coating of copper on the outside. I found the density of the old pennies and found that I was -9.6% off from the actual density. Then I calculated the density of the new pennies. I then looked to see what metals the density was close to. I learned that on the inside of the new pennies is Zinc. This lab also taught me that even if I am the last one done, to take my time, and that by taking my time and really thinking things through even when it seams easy my measurements and calculations will be more accurate.

Chemical and Physical Changes Lab Report

INTRODUCTION (#1)
This lab was done in order to show the difference between physical and chemical changes, differing in that physical changes result in a change in the form of matter but not altering its composition, while chemical changes produce a chemical reaction and a new substance. This lab was also done in order to teach us how to properly spot a chemical reaction in the lab.

INTRODUCTION (2)
The objective for this “Chemical and Physical Changes Lab” was to perform various experiments and observe the changes made. Then, by taking our observations, we can conclude if the change made is a physical or chemical. By the end of the lab, our goal was to be able to distinguish easily the difference between chemical and physical changes.

INTRODUCTION (#3)
We did this lab to find out the differences between chemical and physical changes. We also did this lab to learn about the signs that would indicate the chemical reactions. We needed to learn about the temperature changes, odor change, precipitate, irreversible, color change, and bubbles or gas (new gas).

CONCLUSION (#2)
This lab helped us to learn the difference between chemical and physical changes. In a physical change, the original substances still exist and nothing new has been formed. In a chemical change, new products are formed and it is usually irreversible. Signs that a chemical change has occurred are a change in temperature, a change in odor, a solid is precipitated, it is irreversible or hard to reverse, a change in color, and the production of bubbles, indicating the release of a gas. This lab has introduced us to physical and chemical changes as well as indicators to them.

Mole Lab

A mole is just a large number of “somethings”, such as atoms, molecules, ions, or formula units. Having a mole means having 6.02 x 10²³ of them. You in theory could have one mole of marbles, but they’d likely be larger than the Earth.

Molar mass is when you use your Periodic Table of Elements to count up how many grams would be in exactly one mole of a substance. If the substance is an element, you read this off of the table (the amu of one atom x 6.02 x 10²³ atoms is that number of amu in grams).

For example, 1 atom of carbon is 12 amu. One mole of carbon is 12 grams.

The number 6.02 x 10²³ is called Avogadro’s number, in honor of a famous Italian chemist who worked with gases.

We measured ten jars of exactly one mole of particular atoms. Using our periodic table, we looked up these masses, and determined which element were in the jars.

We then measured six jars of compounds, and determined their molar masses. With a mass, and the molar mass, we could determine how many moles (in these they were all a small part of a mole). Multiplying by 100%, we changed .0625 moles to 6.25% of a mole (for example).

We then did twenty questions to maximize our calculating prowess, and here we are. Moles are neat, moles are huge, and I like moles. You should too.

Stoichiometry Lab

(intro) The objective of this lab was to obtain 2.00 grams of copper 2 sulfate by using a single replacement reaction with iron. The iron will replace the copper in the solution making iron 2 sulfate and we need to determine how much iron is needed for 2.00 grams of copper to be replaced.

(conclusion) In this action-packed lab, we started out by using Stoichiometry in calculating the amount in grams of Fe we would need in order to produce 2.00 grams of Cu. We calculated that we needed 1.75 grams, and then went to work. First, we measured 10.0 grams of crushed copper II sulfate crystals into a 250 mL beaker. Then, we added it to 50 mL of deionized water and heated it over the Bunsen burner, not allowing it to boil. Once the crystals dissolved, we removed them from heat, measured the 1.75 grams of Fe, and slowly added it to the beaker of CuSO4. After letting the solution sit for a while, we folded our filter paper, found its mass to be 1.53 grams, and placed it in the funnel, wetting it with deionized water to keep it down. We then filtered our solution through the funnel and filter paper, and let the filter that caught the copper sit overnight. The next class, we found the filter paper containing the copper to be 3.98 grams, thus telling us that we produced 2.45 grams of copper alone. Our percent error was 23%, with there being a 0.45 gram difference between the amount of copper we should have produced from the 1.75 grams of Fe.

Phases Lab - Lauric Acid

(intro) The purpose of this lab was to determine the melting point/freezing point of Lauric acid. In doing so we set up a graph, which would show a curve that identified the differences in each stage of the cooling of the substance. This lab was useful in lab safety as well as understanding the concepts of Kinetic Energy and Potential Energy.

lab questions
1. The melting point for Lauric acid was 43.2 degrees centigrade. I was able to determine this
    from my graph by identifying where the line became parallel with the x-axis.

2. The line segment BC needs to be parallel with the x-axis because there should be no
    temperature change. The segment BC shows where the phase change occurs. It needs to be
    parallel and constant with the x-axis because the kinetic energy is remaining constant. The
    kinetic energy left is being used to put back together the bonds of the lauric acid molecule.

3. Kinetic energy relates to the three phases of water in different ways. As water goes from a
   solid to a liquid, the kinetic energy is remaining constant. It is being used to break the chemical
   bonds that hold the water together in order to make it into a liquid. As kinetic energy increases
   after becoming the liquid, it will keep increasing until it reaches the next phase change. As it
   reaches the phase between liquid and gas, the kinetic energy remains constant; it begins being
   used to break the chemical bonds in the water so it can form into the gas phase. After that,
   depending on how much heat is added, the kinetic energy will increase, and the gas form of
   water will continue to get hotter.

4. Freezing point and melting point are the same in that they have the same temperature at
   which the phase is changing. If kinetic energy is being added is will begin to melt whatever
   substance is turning. If kinetic energy is being loosed at that point it will begin to freeze.
   At the temperature it takes to melt a substance, is the same temperature it takes to freeze
   that substance. It is all dependent however on whether or not kinetic energy is being added
   or lost.

Conclusion:
     In this lab we heated frozen Lauric acid until it melted into a liquid. From there we observed and recorded its change in temperature every minute until it reached 34 degrees centigrade. After doing so we plotted a graph using our recorded data to show the cooling curve of Lauric acid. [The measured melting point for Lauric acid was 43.2 degrees centigrade.] From here we could determine the exact melting point/freezing point temperature from the graph. This is where the line on the graph becomes completely parallel with the x-axis. It would be due to there being no temperature change, and thus no kinetic energy being released. My line on the graph however was not perfectly parallel with the x-axis at its freezing point. This could have been due to numerous reasons. For instance, inaccurate readings of the thermometers, the actual quality of the thermometers, as well as a slight change in air pressure would result in the graph/data taken being slightly inaccurate. This lab was very useful in understanding the concepts of Kinetic Energy, Potential Energy, as well as using lab safety when experimenting with the Bunsen burners. This lab was also helpful in reading thermometers and recording data, and plotting points to make a graph which would help us better understand our data recorded.

% Composition by Mass of Sugar in Bubble Gum

We learned a lot about the composition of gum, and the role of sugar, by learning about percent composition by mass. Percent composition by mass is not very difficult once you learn the proper steps. To calculate the percent composition by mass of any given compound or other substance you divide the part by the whole and then multiply it by one hundred percent. When calculating the percent composition by mass of a compound we start by finding the molecular mass, with grams per mole. We then take each element of the compound and divide their individual total mass by the total mass of the compound per mole. Then, by multiplying that number by one hundred percent, we are able to calculate the accurate percent composition by mass. This can be extremely useful in finding the correct proportions of ingredients in a substance or in many other circumstances. It is very important to be able to calculate what percentage an element makes up of a compound.

Electrons Lab Report

Introduction (#1)
This lab was done in order to show us the possibility of electron movement from their ground state configuration to higher-than-normal orbitals, and then back down again. We also learned that this movement and subsequent release of energy create a bright light spectra (a series of coloured lines) or a coloured flame unique to the atom the electrons are a part of.

Introduction (#2)
In this lab I learned that gases, and substances can be determined by their bright line spectra. I also learned that electrons in atoms are normally in their ground state unless something in the environment (energy) is absorbed. Then the electrons enter their excited state. When the electrons return to their ground state, and release energy they may give off color. We looked at the lamps for hydrogen, helium, mercury, water, neon, and krypton. We then drew their color spectra. We also looked at the color of the flames of metals. We looked at barium, strontium, copper, potassium, sodium, and lithium. This was a very interesting lab! :)

Conclusion (#1)
In this lab we learned about the color spectra and how to draw one accurately. We lit different elements on fire and saw their colors they let off, which were actually a mixture of colors combined. During this lab we also learned about the ground and excited state of electrons. When at the ground state an electron is “normal”, but when it is given energy, such as heat, it becomes “excited”. During the “excited state” the electrons jump to a higher orbital causing the electron configuration to change but the mass must remain the same. And when the electrons go back to the ground state, which is when it lets off its energy, which we see as colored flames or spectra lines if we have our refractive lens glasses.