6.03 Calorimetry Lab

Because it is dangerous to burn magnesium, it is not possible to directly record heat change. Our lab team suggests an indirect way of determining the heat of combustion for magnesium. To accomplish this, we need to perform two separate trials. One uses a solid (powder) version of MgO, while the other uses Mg ribbon. With the results from these, we can use Hess’ Law to determine q=∆H. This provides both a safe and successful way of indirectly determining the heat of combustion for magnesium.

An experiment was carried out to predict the limiting reactant in a chemical reaction between Magnesium and Hydrochloric acid, using the mole concept.

Hypothesis/Prediction: The percent composition by mass of magnesium in magnesium oxide will not change significantly with each group that conducted the experiment. The composition of each substance should stay the same and any differences must be due to some error.

The purpose of this lab was to test the law of definite proportions for the synthesis reaction of combusting magnesium. In this lab, the polished magnesium ribbon was placed in covered crucible and was heated in order for it to react with Oxygen presented in air and in water provided. The result showed that Magnesium oxide formed through chemical reaction was made up of 60.19% magnesium and 39.81% oxygen, which is approximate proportion of both particles in every Magnesium oxide compound. From this lab it can be concluded that the law of definite proportion stating that the elements in a pure compound combine in definite proportion to each other is factual.

For example, Brooke and Lily’s mass of their reactants was 32.3 grams. Likewise, after their experiment was performed the mass was also 32.3

The first experiment is about the combustion of magnesium after which the ash is formed.

Molar Mass is basically in grams per mole for example salt has a molar mass of 5.8g per mole. The mass of an element refers to 6.0221415x1023 molecules of the substance. Molar Mass helps us figure out how many grams per mole we need to do this project and it helps us know how much we need to put into the solution. If you don’t Find

For the first trial, after .398 grams of magnesium were mixed with .251 grams of oxygen, the result yielded .649 grams of magnesium oxide. In the second trial, after .404 grams of magnesium were mixed with .132 grams of oxygen, the result yielded .536 grams of magnesium oxide. In the third trial, after .406 grams of magnesium were mixed with .702 grams of oxygen, the result yielded 1.108 grams of magnesium oxide. All three of the trials yielded different results in the data table; but, there were only two different empirical formulas, percent compositions and mole ratios for each of the trials. For the first trial, the empirical formula was MgO and the percent composition for magnesium was 60.31% and the percent composition for oxygen was 39.69%. For the second trial, the empirical formula was Mg2O and the percent composition for magnesium was 75.24% and the percent composition for oxygen was 25%. For the last trial, the empirical formula was MgO but that was after the simplification of the original empirical formula, Mg2O2, and the percent composition for magnesium was 60.31% and the percent composition for oxygen was 39.69%. In conclusion, when heat and oxygen were applied to the magnesium, the common empirical formula that was derived from magnesium and oxide was MgO.

) 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.

How empirical formula of Magnesium Oxide is obtained by heating Magnesium in the presence of air?

The mass of the Magnesium ribbon was calculated using a balance that goes to the 1,000 of a gram. The Magnesium was rolled it into a coil and tied with a string the the stopper. The stopper had a hole in the top, without the stopper the lab can become very dangerous. The eudiometer was taken and 10 ml of 3 molar hydrochloride acid was placed into the eudiometer. Following, the eudiometer was filled with water so there was no air. Then, the stopped was out on top with he magnesium on the inside. The beaker was filled about half way with water. The temperature of the water was taken.The hole in the stopper was covered with a finger and the stopper was put in the water. When the eudiometer was flipped over the hydrochloride acid went to the bottom because hydrochloride acid is more dense then water. When the hydrochloride acid reached the coil of Magnesium a single replace meant reaction took place. Hydrogen is lighter then water and went back up to the top of the eudiometer and push the water out of the eudiometer. The reaction went on till no bubbles (hydrogen) were rising from the

    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.

During the experiment, 0.1400 g of Magnesium reacted with Oxygen (O2) in air to form .2300 g of Magnesium Oxide. The loosely spiral magnesium ribbon (approximately 16 cm) which had a shiny characteristic was turned into a dull grey powder after the reaction took place. The percent error for this experiment was 0.9453% error. This was found by calculating the following: ((Theoretical % - Experimental %) / Theoretical %) x 100. The error could have happened because since the reaction of Mg and O2 is so exothermic (temperatures above 1000 degree Celsius are obtained during the reaction), some Mg might have reacted with the N2 in the air (since the air contains 78% N2 and 21% O2) to create magnesium nitride (Mg3N2(s). The balance equation for this

Magnesium is a chemical element with symbol Mg and atomic number 12. Magnesium is a shiny

This is because the Law of Conservation of Mass states, in any given chemical reaction, the total mass of the reactants equal the total mass of the products. In Part B the total mass of the reactants did not equal the total mass of the products. There was in fact a difference of 0.62grams between the reactants and the produced mass.