Therefore the discrepancies in the experiment, however small, could have led to a lower value than expected which resulted in the low percent error. The top of the calorimeter could also be covered with aluminum, this would not only cover the holes but would secure the space under the lid so any heat that may escape would stay within the area due to the aluminum.
The formation reaction is a constant pressure and constant temperature process. Many bubbles are forming. This is true for all enthalpies of formation. Once again, the change that would have occurred would have been minimal as it is difficult for large amounts of magnesium to react with oxygen in such a short amount of time without the use of a catalyst.
However, due to small sizes of the holes and the security of the lid it is unlikely that a large amount of heat would have escaped which is why only a minimal change would occur, much like in the case of this experiment. A gas is beginning to form, only a little bit.
In other words, if a chemical change takes place by several different routes, the overall enthalpy change is the same. And by the way, everything was happening in a water environment. The MgO has completely dissolved in the HCl. Another discrepancy that may have occurred during the experiment was that the magnesium strip may have reacted with the oxygen in the air before it was poured into the calorimeter.
A lot of gas is forming. Chemical reactions require heat energy to complete, called an endothermic reaction, or produce heat energy, and thus called an exothermic reaction - Heat of formation of magnesium oxide introduction.
To prevent even the slightest anomalies, in future any holes on the calorimeter can be covered by tape or another item that could block the passage. In the future the procedure should emphasize the importance of measuring and pouring the magnesium after the HCl has been measured and poured into the calorimeter, this would prevent other reactions from occurring.
As per lab manual we used a calibrated calorimeter using a rounded end thermometer so as to not puncture a hole in the calorimeter to determine the heats of reaction for Magnesium Mg with Hydrochloric Acid HCl and Hydrochloric Acid with Magnesium Oxide MgO.
When this Heat of formation of magnesium oxide change is multiplied by the heat capacity, the amount of heat needed to raise the temperature of a body by one degree, we can measure the change in converting our initial components reactants to their respective products.
One error that may have caused a lower enthalpy of change value than expected could have been that heat escaped from the calorimeter used during the experiment. According to my understanding a catalyst, at least theoretically, is not consumed in the reaction.
It is evident that the two equations which were used in this experiment were exothermic since the enthalpy of change that resulted was a negative value, therefore the experiment was successful.
Posted 09 December - Check the contents of the calorimeter. These holes could have let heat escape as the reaction was taking place which would have lowered the final temperature value.
When this temperature change is multiplied by the heat capacity, the amount of heat needed to raise the temperature of a body by one degree, we can measure the change in converting our initial components reactants to their respective products.
There were two holes on the lid of the calorimeter and one was being used for the thermometer, however the second, although very small, was left open. Therefore, the average temperature high for the MgO and HCl solution in trial 1 was Therefore, the average temperature high for the MgO and HCl solution in trial 2 was We then recorded the mass m of room temperature water and ice water each in a respective cup and then poured the ice water into the room temperature water and recorded the temperature change.
Read the temperature of the reaction mixture every 15 seconds, until it reaches a maximum. Consequently, this would have led to a decrease in the mass of the magnesium, one that would have been unknown at the time.
However, this would explain the small error in this experiment as the discrepancies were not that high. This implies that the reaction is exothermic. Aluminum could also be tucked in the space between the lid and the calorimeter to once again lock the heat in.
Disposed the reaction of solution. Wash the cup with water, and dry it with paper towels or tissues. Therefore, the average temperature high for the Mg and HCl solution in trial 2 was The Heat of Formation of Beryllium Oxide 1.
Lee A. Cosgrove, Paul E. Snyder. Journal of the American Chemical Society 75 (13) The Conductance of Non-aqueous Solutions of Magnesium and Calcium Perchlorates 1.
Journal of the American Chemical Society. Rysselberghe, Fristrom. 67. Enthalpy of formation of solid at standard conditions Data from NIST Standard Reference Database NIST Chemistry WebBook The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound.
The combustion of magnesium creates so much energy so quickly that it is hard to measure its enthalpy directly using a simple calorimeter. However, you will break this reaction down into other intermediate reactions whose enthalpies you can – and will – measure.
Enthalpy Change of a reaction using Hess's Law Objective-to determine the standard state Heat of Formation of Magnesium Oxide using Hess's Law Prelab- Write the balanced equations for the following reactions.
Like calcium, magnesium oxide occurs in minerals such as magnesite (magnesium carbonate) and dolomite (a mixture of calcium and magnesium carbonates).
It is the eighth most abundant element in .Download