Observation: • Magnesium ribbon started to glow when it was heated strongly • There was a change in the colour of magnesium from silver to grayish white • When the lid was opened, white ashes (MgO) escaped from the crucible while heating
Evaluation:
The purpose of the lab was to determine the empirical formula of a compound (magnesium oxide). In order to calculate the empirical formula, the mass of each element in the compound was determined. Then, the number of moles of each element in the sample was calculated. Finally, the molar ratio of each element as the smallest whole number was expressed, yielding the compounds empirical formula. The expected empirical formula of Magnesium Oxide was a 1:1 ratio.
An error may have occurred from a simple rounding mistake, or all of the Magnesium may not have burned off during the experiment. If any of the unreacted Magnesium was left in the crucible, the empirical formula would be inaccurate because all of the metal would not have been converted to Magnesium Oxide (the formula would not be 1:1). In the future, I would allow more time for the Magnesium to burn off, assuring accuracy throughout the experiment.
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In all of my five trials, I needed to open the lid to allow oxygen to enter the crucible and react with the hot magnesium ribbon to form magnesium oxide. In this process, some white ash (MgO) escaped due to the strong heat due to convectional currents. Thus, this affected the mass on the product side. • The instable values in electronic balance. This is due to the small changes in mass. The values are only significant with more decimal places, but cannot be shown on the electronic balance. As a result, the machine rounds off the values when they overreach the range of the
During week 1 of this experiment, we recorded common components of fertilizers and then went on to find the chemical formulas involved in creating them. The second week we began the process of comparing three authentic ions we had established in the first week to ion samples to discover other properties they might contain. We decided to discover these different ingredients by preforming a serious of tests, which included placing 0.2g solid of both the authentic and the sample fertilizer separately, in order to establish a constant, and dissolved the fertilizer in 20 mL of water, then checked to see if Mg was present in the sample solution. By setting up a constant and preforming a methodical experiment all on the samples given, we demonstrated the ability to correctly establish and preform an experiment and solve the problem at hand, which was distinguishing the contents of the authentic
Our procedure though was not without its mistakes. These mistakes are vital because they affect the data we conclude. Theoretically, according to the balanced chemical equation, for every mole of hydrated cobaltous chloride that is being heated, the decomposition ensures that the compound decomposes into one mole of cobalt(II) chloride and six moles of gaseous water vapor. Thus, in theory we should lose the mass equal to six moles of water vapor in each trial. Unfortunately, this is not the case because we don’t have perfect lab conditions and factors such as the time heated, utilization of the same crucible, and the inconsistency of magnitude of the flame from the Bunsen burner all contribute to differences in mass percent change for each
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.
This process is then repeated. In the second trial, the Mg ribbon did not completely dissolve and the results were thrown out. The third trial (referred to as the second in the following analysis due to the exclusion of the previous one) was successful, and measurements can be seen below. We then moved onto the second reaction using magnesium oxide and hydrochloric acid in the fume hood. We measured 200.1 mL of HCl and placed it in the calorimeter, and an initial temperature reading was taken.
Mass of O = Mass of crucible, cover, KClO3 and MnO2 after heating (Step # 11) - Mass of crucible, cover, KClO3 and MnO2 before heating (Step # 5)
The mass of Mg + the mass of O2=mass of MgxOx. Knowing the mass of
Aim: The aim of this experiment was to determine the empirical formula of magnesium oxide.
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.
Other methods available consisted of timing how long it took for the magnesium to disappear. We would place the liquid and the magnesium in a flask and start the timer, one reason we chose not do this is we won’t precisely know when the reaction is finished. Plus people might have different opinions of when the magnesium has disappeared. Another is timing how long it takes for a solution to turn cloudy. We would again place the liquid and the magnesium in a flask and start our timer, the reason...
The data supports my hypothesis that if the length of the magnesium strip is increased (in millimeters), then the volume of gas (in milliliters) also increases. As the length of the magnesium strip increases one millimeter, the volume of gas increases on average about 7.417 milliliter. This proves that the length of magnesium has a direct impact on the volume of gas after the magnesium is combined with acid. The data also proves that the relationship between the length of the magnesium strip and the volume of gas produced is a linear relationship. The range in the increase of volume of gas is 42-47 milliliters for every five millimeters of magnesium. This shows that the relationship between the milliliters of gas produced is linear (increasing
To determine if the mass increases when we burn the magnesium and change it into magnesium oxide
Molar mass is a fundamental and must-know term in chemistry. Anyone who studies chemistry begins the journey with this term. The molar mass of a substance is defined as “the mass of one mole of any substance where the carbon-12 isotope is assigned a value of exactly 12gmol-1. Its symbol is M. Molar mass is important because of its usefulness in various calculations. To chemistry students, it is a tool to solve many problems and exercises, as molar mass can be used to calculate the mass or the amount of a sample of a certain substance. Obviously, the most popular way to determine a substance’s molar mass is by using its chemical formula. Another way is to use a sample of that substance and calculate from the mass and the amount of substance. However, not many people would think of using titration and back titration to calculate the molar mass of a substance.
3 cm of magnesium ribbon generally has a mass of 0.04 g and yields 40 cm3 of hydrogen when reacted with excess acid. 50 cm3 of 1M hydrochloric in this experiment is in excess.
This first laboratory exercise has two primary goals. The first goal is to practice the classical techniques of weighing with balances and making volumetric measurements using glassware. For much of analytical chemistry, the accuracy of the entire analysis depends on the accuracy to which the standard (or standards) are compared. The second goal is to introduce and utilize certain concepts of statistical treatment of data. Carefully obtained results are useless unless their values and their limitations are known. The following statistical concepts are introduced in this laboratory exercise: accuracy and precision (absolute and relative); estimation of error (deviation); propagation of error; significant figures; Gaussian (normal) distribution; average (mean); median; standard deviation; and confidence interval.
It is evident that the mass measurement were not the same for the three trials performed. Even though, the penny being weighed is the same for all three trials, the mass recorded were not the same for all. This inaccurate calibration of the scale may have affected the results for the measurement of mass. Aside from the scale, the caliper could have caused inaccuracies in the data collected. From the three trials of the recorded diameter and height, it was evident that the measurements of the caliper showed variations also. Because of this, the caliper is also a source of the inaccuracies of the data. Also, the conditions of the pennies that were used in the experiment were not exactly the same with each other. For example, some pennies are have a lot of dirt on it. The dirt in the penny could increase the mass and volume of the penny so it caused inaccuracies in the data as