Magnesium and MgO

With the mass of oxygen found, 0.02 grams, the percent compositions of magnesium and oxygen can be found by dividing their masses by the total mass of the new compound:

Using elemental analysis to determine the percent mass composition of each element in a compound is the first step in creating an empirical formula. There are many different types of elemental analysis, but in this experiment gravitational analysis and Beer’s Law are used. Elemental analysis is first used to find the moles of each element, then converted to mass, and then the percent mass of the element in the product is found (2).

The additional ice that melted was added to the initial mass of water to obtain the final weight of water in the solution to calculate molality:

) 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.

About 80 mL of HCl was obtained and mixed with phenolphthalein. Using a LabQuest unit and Gas Pressure Sensor kit, the HCl mixture was added to the flask with the magnesium ribbon and allowed to react. When reaction was complete, the change of temperature and gas was recorded. This procedure was repeated for different masses of magnesium ribbon (masses found on page 89 of the lab manual). After the completed procedure, moles of H₂ produced in each trial were calculated. (The actual procedure can be found on pages 87-89 of the lab manual)

A1.Work under the hood! With a pair of tongs, hold a strip of magnesium in a bunsen burner flame. Do not look directly at the flame. Save the ash in a small beaker for the next procedure. If magnesium is substance "A" in the general equation, what is "B"?

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

1. Label each substance on seven pieces of paper. Put two pieces of magnesium ribbon on the paper labeled “Magnesium”.

The solubility of Mg(OH)2 (Ksp = 8.9 10-12) in 1.0 L of a solution buffered (with large capacity) at pH 9.58 is:

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

    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 goal of this experiment was to determine the empirical formula for a hydrate of magnesium sulfate and water. The technique that was used was measure the mass of the hydrate and then apply heat to evaporate the water. Then determine the mass of water that was in the hydrate and the mass of the remaining magnesium sulfate. The equation for the hydrate is determined by calculating the mole to mole ratio of the water and the anhydrous. The resulting formula will be formated as: MgSO4*_H2O

5.3 mL of bromobenzne and 15 mL of anhydrous ether was then placed into the separatory funnel and was shaken and vented in order to mix the solution. Half of the bromobenzene solution was added first into the round bottom flask and as soon as a color change was observed, the remaining half of the bromobenzene was added drop wise into the round bottom flask. The mixture was then refluxed on a heating mantle for 10 minutes until most of the magnesium has been consumed.

I could use a gas syringe to collect the gas that will evolve from my

In the experiment the magnesium reacts with the hydrochloric acid to create magnesium chloride and hydrogen. The balanced formula for this is: