Lab Write Up Two: Natalie Earnest, Liz Seehase, Connor Moroney, Abdulhakim Alnasser
Beginning Questions:
What are the percentages by mass of the three compounds: NH4Cl, NaCl, and SiO2?
How accurate are our percentages?
Procedure:
Claims: During our lab we found our mass percentages for our sample to consist of 20.5% of NH4CL, 48.5% of NaCl, and 25.6% of SiO2. Being that the actual percentages of our mixture were 20% of NH4CL, 50% of NaCl, and 30% of SiO2. After using the percent error equation that was provided to us in class we found there to be a 5.4% error which is relatively accurate.
Reading and Reflections
During this lab there were a few instances where errors could have occurred and affected our results. Our calculations showed that we had 20.51% of NH4Cl in our mixture. However, we were only supposed to get 20%. We could have gotten over the amount possible by rounding our masses wrong or going with a mass number that was not the most accurate. The scale would not sabilize for very long when we were weighing the total mass, so we chose the mass that the scale stopped at the most. This mass might not have been the more accurate. In regards to the NaCl, some of the salt could have gotten trapped in the coffee filter when we were separating the
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Since the weight did not decrease, the sample did not get separated. Since the initial mass was smaller than the final mass the students could have made an error on their original mass weighing. The students could have tared the scale incorrectly or not at all. We found when we were weighing masses that our scale would stabilize at a negative number while nothing was on the scale, before we tore it. This could account for the small initial
The purpose of this lab was to calculate the specific heat of a metal cylinder
Cu (aq) + 2NO3 (aq) + 2Na+ (aq) + 2OH- (aq) → Cu(OH)2 (s) + 2Na+ (aq) + 2NO3(aq)
Discussion: The percent of errors is 59.62%. Several errors could have happened during the experiment. Weak techniques may occur.
In this, someone could have simply read the measurements wrong, causing an incorrect result. From this, we have learned to try and be as accurate as possible and make sure to be taking the correct measurements. For a further experiment, I would recommend just a few changes to try and prevent any human error. Next time we could assign one person to each table to be accurately measuring the height of the bags to make the process more efficient. In our group, the possibility of human error was pretty high so assigning one person could make the experiment more precise.
In this experiment, there were several objectives. First, this lab was designed to determine the difference, if any, between the densities of Coke and Diet Coke. It was designed to evaluate the accuracy and precision of several lab equipment measurements. This lab was also designed to be an introduction to the LabQuest Data and the Logger Pro data analysis database. Random, systematic, and gross errors are errors made during experiments that can have significant effects to the results. Random errors do not really have a specific cause, but still causes a few of the measurements to either be a little high or a little low. Systematic errors occur when there are limitations or mistakes on lab equipment or lab procedures. These kinds of errors cause measurements to be either be always high or always low. The last kind of error is gross errors. Gross errors occur when machines or equipment fail completely. However, gross errors usually occur due to a personal mistake. For this experiment, the number of significant figures is very important and depends on the equipment being used. When using the volumetric pipette and burette, the measurements are rounded to the hundredth place while in a graduated cylinder, it is rounded to the tenth place.
A random error is caused by any factor which randomly affects the amount of scatter in the data. An increase in sample size allows averages to be calculated which reduces the effects of these random errors. By removing outliers in the data, the effect of random errors can be further minimised. A large amount of scatter in results indicated low precision and a large number of random errors. Some possible random errors in this experiment may have arisen when measuring the 12mL of milk solution for each test tube; some may have had slightly more and others slightly less than 12mL. Another random error could have occurred when adding 4 drops of methylene blue, some drops may have contained more liquid than others, meaning some test tubes may have contained less methylene blue indicator than
Extraction is a separation method that is often used in the laboratory to separate one or more components from a mixture. Sucrose was separated at the beginning because it is the most immiscible and it’s strongly insoluble. Next Acetylsalicylic Acid was separated which left Acetanilide alone. Variety steps could have led to errors occurring. For example the step of separation, when dichloromethane layer was supposed to be drained out, it could be possible some aqueous layer was drained with it. Which could make the end result not as accurate. Also errors could have occurred if possibly some dichloromethane was not drained out. Both way could interfere with end result of figuring the amount of each component in the mixture. The solids percentage were 22.1% more than the original. That suggests that solids weren’t separated completely which clarifies the reason the melting points that were recorded were a slightly lower than the actual component’s melting point. The melting point for Acetylsalicylic Acid is 136 C but that range that was recorded during the experiment was around 105 C to 118 C. The melting points were slightly lower than the literature value. Sucrose was the purest among all component due to its higher melting point which follows the chemical rule that the higher the melting point the more pure the component
...ore reliable if it were possible to do more trials to make sure that the data that was found was correct. This experiment could’ve been more reliable if some mistakes weren’t made like, the inaccuracy of weighing and measuring the potatoes. This could have affected the results by throwing off all the data and giving numbers that were nowhere near accurate. Another mistake that could’ve been made was the amount of solution put into each test tube. Some of the test tubes may have had to little or not enough of its solution. Some ways to fix both of these problems would be to weigh and measure each potato core more than once which is not what was done. A way to fix the inaccuracy of the amount of salt water put into each test tube would be to measure the solutions into a different container to make sure it’s an accurate measurement, then pouring it into the test tube.
"A ""A Hne"A hen is only an egg's way of making another egg." ~ Samuel Butler making another egg."
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
Objective The ability to analyze a substance and determine properties of the substance is an important skill for AP Chemistry students. Major concepts for the “Analysis of Alum” laboratory are percent composition, water of hydration, and molecular formula. They will be used in three different experiments to determine the melting point of alum, the mole ratio of hydrated water to anhydrous alum, and percent of sulfate ion contained in alum. The values acquired in the lab should be close to the calculated values of 92.5 ˚F, 12 moles of water to 1 mole of alum, and 59%, respectively.
Mass Pb(NO2)3/ MW Pb(NO3)2 to find the mass of SO4, which equaled 0.1394g, then plugged into the percentage was exactly 55.75% SO4. The begging of the experiment requested that the percentage of SO4 in their fertilizer sample be found and that is exactly what was accomplished by this experiment, and the outcome, demonstrating the ability of my group to preform the requested task presented by the
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
is impossible to specify a single best method to carry out a given analysis in