Percent Composition Lab Report

The purpose of the lab was to determine the percent of water in the hydrate MgSO4 * N2H0 through the process of heating the hydrate, releasing the water molecules, and leaving only the anhydrous magnesium sulfate and also determine the number of water molecules in the hydrate. Throughout the lab, various masses were tooki, including the mass of the evaporating glass with the watch glass, the mass of the evaporating glass, and watch glass with the additional hydrate sample, and the mass of the the evaporating glass, and the watch glass with the dehydrated sample, at two different times, each separated by a five minute interval. After, calculations based on the mass of the left over anhydrous solution were made where the mass of the either the original recorded number for the hydrate was used, or the aftermath dehydrated value of the hydrate. Soon the mass converted

) Suppose that some magnesium oxide smoke had escaped during the investigation, the Mg:O ratio would have increased from 58% to 72%. The final mass of MgO would have decreased because the magnesium oxide smoke is part of the product and when some of it escapes, it decreases the final mass.

However, the results of this experiment may not have been as accurate or precise as they

Purpose: To determine the percent magnesium by mass in magnesium oxide and to observe if the percentage composition is constant by comparing class results.

Based on my and other classmates' observations and results it can be proved that every time magnesium combines with oxygen to form Magnesium oxide the percent composition for magnesium will be 60.31% and for oxygen it will be 30.69 % (the results achieved by experiments are

    In this lab, a calorimeter was used to find the enthalpy of reaction for two reactions, the first was between magnesium and 1 molar hydrochloric acid, and the second was between magnesium oxide and 1 molar hydrochloric acid. After the enthalpy for both of these were found, Hess’ law was used to find the molar enthalpy of combustion of magnesium, using the enthalpies for the two previous reactions and the enthalpy of formation for water. The enthalpy of reaction for the magnesium + hydrochloric acid reaction was found to be -812.76 kJ. The enthalpy of reaction for the magnesium oxide + hydrochloric acid reaction was found to be -111.06 kJ. These two enthalpies and the enthalpy of formation for water were manipulated and added together using Hess’s law to get the molar enthalpy of combustion of magnesium. It was found that the molar enthalpy of combustion of magnesium was -987.5 kJ/mol. The accepted enthalpy was -601.6 kJ/mol, which means that there is a percent difference of 64%. This percent difference is very high which indicates that this type of experiment is very inefficient for finding the molar enthalpy of combustion of magnesium. Most likely, a there are many errors in this simple calorimeter experiment that make it inefficient for finding the molar enthalpy of combustion of magnesium.

The purpose of this experiment is using Compleximetric titration and EDTA to determine the concentration of Mg2+ in solution; and also calculating the percent by mass of MgO in the unknown sample. This procedure results no significant deviations.

5. The degree of precision was to 3 significant figures obtained with the spectrophotometer. The major source of error in our experiment was not calibrating the spectrophotometer with distilled water.

Spectrophotometers are quite precise instruments allowing for five significant figures to be obtained. The major source of error in this lab is how small the concentration of the reagents are.

The purpose of this experiment is to verify the formula of magnesium oxide based on the masses of magnesium and the product (MgO). We verify the formula firstly by calculating the empirical formula of magnesium oxide and then calculating creating the magnesium oxide itself- a magnesium ribbon is combined with oxygen in the presence of air through combustion and this forms MgO. The empirical formula of a compound is the simplest method of expressing a chemical formula in whole-number ratios of the constituent atoms that are consistent with masses measured in the experiment; whereas the molecular formula expresses the chemical formula using the actual number of atoms. For example, the molecular formula of anthracene is C14H10 while the empirical formula is C7H5.

2. (5 pts) List and explain the names and affiliations of the various characters/stakeholders in this story – I’m looking for us to use the story to map out the complexities that are generally associated with solving public health puzzles – the stakeholders you list and explain here should apply to many of the cases we consider going forward.

This experiment shall be repeated twice or more to enhance accuracy of the results obtained. Besides detecting systematic errors, this experiment would aid on the technique and understandings to the correct use of these equipments.

In 1909 S.P.L. Sorensen published a paper in Biochem Z in which he discussed the effect of H1+ ions on the activity of enzymes. In the paper he invented the term pH to describe this effect and defined it as the -log[H1+ ]. In 1924 Sorensen realized that the pH of a solution is a function of the "activity" of the H1+ ion not the concentration and published a second paper on the subject. A better definition would be pH=-log[aH1+ ], where aH1+ denotes the activity of the H1+ ion. The activity of an ion is a function of many variables of which concentration is one. It is unfortunate that chemistry texts use a definition for pH that has been obsolete for over 50 years.

In this experiment we combined magnesium metal with oxygen in air by heating. We used the measured mass of magnesium metal and magnesium oxide to determine the empirical formula of the oxide product. We had to find the experimental percent composition (by mass) of MgO, come up with the experimental empirical formula of magnesium oxide, and balance the chemical equation: Mg (s) + O2 (g) → MgxOy (s).

As a result of this finding, the Head of Quality Assurance has requested full validation to be performed on the method to assure the quality of the assay results generated