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Purpose To measure the enthalpy change of two different reactions in the laboratory. To use Hess's Law to estimate the enthalpy change for the reaction: In order to perform the calculations at the end of this lab, there are a few things you must know: The specific heat s of the solution will be estimated to be the same as that of water, or 4.
The systems you are studying are reactions a and b above. The surroundings include the calorimeter and the solution. Use the combined mass of all reagents solids and solutions used in each trial for the mass of the solution m. Heat gained by the system is lost from the surroundings.
Heat lost by the system is released to the surroundings. This is otherwise known as the Law of Conservation of Energy.
Seek assistance from the instructor, if necessary. Students who served as a manager or computer operator will work as lab techs for this activity.
In the event you had only 3 students the first time, or if a group member has dropped since then, you may make your own assignments, but you should take on a different role than last time. However, each individual should have had a chance to do some of the dirty work, as well as some of the greater responsibility of getting the assignment submitted to the professor in a timely manner.
To refresh your memory on the role played by each person, you may check out the group work page. Adjust the experiment length to s and set the sampling rate to 5 seconds per sample.
Place your calorimeter onto an electronic balance use a cheap, less precise balance for this measurement, as you do not want to risk spilling acid on the analytical balance and tare the balance. Remove the calorimeter from the balance and carefully add Place the cup back onto the balance and record the mass of HCl added.
Also, record the volume of HCl used. Slide the temperature probe into the small notch cutout on the cardboard cover and place the probe into the HCl. Stir the HCl with the probe to maintain a uniform temperature throughout the solution.
Wait until the temperature stabilizes. Roll the magnesium ribbon into a loose ball. Click the green "Collect" button to begin data collection. After a couple of data points have been collected, slide the cover aside and drop the ball of magnesium into the calorimeter.
Slide the cover back into place. Continue stirring until the data collection ends. Select Store Latest Run from the Experiment menu and save your data to disk. Repeat Steps twice to obtain a total of three trials with the magnesium reaction with hydrochloric acid.
If your data looks good, copy and paste the data from each of your trials into an Excel spreadsheet. Use the appropriate function or formula to determine the minimum and maximum temperatures reached in each trial. Assignment use the answers to questions in your Results and to questions in your Discussion Determine which substance is the limiting reactant in the reaction of magnesium with hydrochloric acid, then in the reaction of magnesium oxide with hydrochloric acid.
How many moles of the limiting reactant were used in each of the reactions? Provide at least one sample calculation for each of the two types of reactions. If you are submitting the report electronically, you may place formulas in spreadsheet cells instead.
See the introduction for helpful information and equations. Look at the coefficients of the limiting reactant in each of the equations.
Don't make this conversion difficult. Use Hess's Law of Heat Summation, the class average enthalpy changes for reactions a and band the enthalpy change for c given above to determine the enthalpy change for reaction d.
What were some possible sources of error in this experiment? Laboratory Report You will be turning in a group laboratory report.
The report should include the title information, an introduction to thermochemistry in general different from the introduction in this lab manualexperimental details properly referenced if you choose that routeresults, discussion, and references. You should use the above questions to guide your results and discussion, but there should be more to these sections than just answering the questions and they show flow logically as you discuss the lab and the results.
Follow your instructor's directions for submitting this lab report.Dec 13, · Does anyone know the actual molar enthalpy of combustion of magnesium in KJ/mol????? and where did you get the info from?? Heat of Combustion J/(Kg K). HELP! Molar enthalpy of combustion of magnesium?Status: Resolved.
LAB FOUR Specific Heat of a Metal 1 Name Lab Partner(s) Section Date Magnesium Tin Zinc Specific Heat of a Metal 5 Name Lab Partner(s) Section Date Report: Specific Heat of a Metal: Data Trial 1 Trial 2 Mass of calorimeter. Mass of calorimeter and water Mass of water Mass of metal.
Using Hess’s Law to Calculate Heat of Formation of of Magnesium Oxide Essay - Heats of Reaction and Hess’s Law Lab Background: Thermochemistry is the branch of chemistry that deals with the amounts of heat evolved or absorbed during chemical reactions. When the pressure is constant, the amount of heat gained or lost in a chemical or.
Lab -Stoichiometry of Magnesium Oxide Goggles must be worn at all times Introduction: Heat the crucible to redness, for four minutes 7) Turn off the Bunsen burner and allow the crucible to cool to a temperature low enough so that you can touch the crucible.
The report should include the title information, an introduction to thermochemistry in general (different from the introduction in this lab manual), experimental details (properly referenced if you choose that route), results, discussion, and references.
Goggles must be worn at all times in the lab. specific heat) of experimental determination of the heat of solution of a soluble salt, Heat Of Reaction For The Combustion Of Magnesium Lab Report.