Preview

Hess' Law

Satisfactory Essays
Open Document
Open Document
380 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Hess' Law
Hess’ Law

To find out the enthalpy change of Mg+ ½O2=MgO, we used a calorimeter, thermometer, 0.2 g of Mg, 0.2 g of MgO, and 2.0 M of HCl. We used a thermometer to measure the initial and final temperatures in Celcius. We recorded the initial temperature of the HCl. After we put the Mg or MgO into the calorimeter, we put in the HCl and covered it using a lid, mixed it around with the thermometer, and recorded the final temperature. We also used this method to find the enthalpies of the equations for the reactions.
Data:
Trial #
Mass of Mg
Mass of HCl
Initial Temperature
Final Temperature
1
0.2 g
10.01 g
23.67 °C
88.19 °C
2
0.2 g
10.11 g
24.71 °C
84.51 °C

Trial #
Mass of MgO
Mass of HCl
Initial Temperature
Final Temperature
1
0.2 g
9.79 g
22.97°C
40.27°C
2
0.2 g
9.91 g
23.19°C
38.43°C

Calculations: ** The -Qreaction=Qsolution**

Mg:
Trial 1: q=mCΔT q=10.01g x 4.184 J/g°C x (88.19-23.67)°C= 2699.52 J =2.70 kJ
0.2g Mg x1 mole Mg/24.31 Mg=0.0082 mol Mg
-2.70 kJ/0.0082 mol = -329.27 kJ/mol = ΔH
Trial 2: q=mCΔT q=10.11g x 4.184 J/g°C x (84.51-24.71)°C=2529.55 J =2.53 kJ
0.2g Mg x1 mole Mg/24.31 Mg=0.0082 mol Mg
-2.53 kJ/0.0082 mol = -308.54 kJ/mol = ΔH
*Average of the ΔH for Mg= -318.9 kJ/mol
MgO:
Trial 1: q=mCΔT q= 9.79g x 4.184 J/g°C x (40.27-22.97)°C= 708.63 J = 0.71 kJ
0.2 MgO x 1 mole MgO/40.31 MgO=0.005 mol MgO
-0.71 kJ/0.005 mol = -142.0 kJ/mol = ΔH
Trial 2: q=mCΔT q= 9.91g x 4.184 J/g°C x (38.43-23.19) °C = 631.90 J = 0.63 kJ
0.2 MgO x 1 mole MgO/40.31 MgO=0.005 mol MgO
-0.63 kJ/ 0.005 mol = -126 kJ/mol = ΔH
*Average of the ΔH for MgO =-134 kJ/mol
--------------------------------------------------------------------------------------------------
Given: Mg+ ½O2MgO
Mg (s) + 2HCl (aq)  MgCl2 (aq) + H2 (l) ΔH= -318.905 kJ/mol
MgO (s) + 2HCl (aq)  MgCl2 (aq) + H2O (l) ΔH= -134 kJ/mol
H2 (l) + ½ O2 (g)  H2O (l) + heat ΔH= -285.8 kJ/mol
---------------
Given: Mg+ ½O2MgO
Mg (s) + 2HCl (aq)

You May Also Find These Documents Helpful

  • Good Essays

    To find this formula, a strip of Magnesium ribbon was burned in a crucible over a flame from a bunson burner. After the strip caught fire multiple times with the cover on, and 10 drops of distilled water were added, and the crucible was lightly heated. The crucible was then weighed and the mass recorded. Calculations were performed and the mole ratio of Mg to O was recorded. The results of other lab groups performing the same experiment were also recorded.…

    • 408 Words
    • 2 Pages
    Good Essays
  • Satisfactory Essays

    H2 Unit 3 Lab Report

    • 293 Words
    • 2 Pages

    4. Calculate the # of atoms of Magnesium that were involved in the reaction – use Avagadro’s number – remember units!…

    • 293 Words
    • 2 Pages
    Satisfactory Essays
  • Better Essays

    Get Charged Up Lab Report

    • 1848 Words
    • 6 Pages

    To accomplish this, three different methods were used. Titration was used to react NaOH with HCl to determine the amount of H+ left over after the reaction is complete. Crystallization was used to determine the amount of MgCl₂ made after the reaction is done. Both of these methods allowed us to calculate the amount of H+ reacting with the amount of Mg. The gas law method and the Ideal Gas Law was also used to determine the mole ratio of magnesium metal to hydrochloric acid by measuring the amount of hydrogen gas based on the pressure and temperature changes during the reaction. With the results from each procedure, graphs were constructed and the most accurate and precise method was discernible.…

    • 1848 Words
    • 6 Pages
    Better Essays
  • Good Essays

    Initial and Final Temperature of Three Different Consecutive Trials of Magnesium and Hydrochloric Acid Reactions…

    • 2480 Words
    • 10 Pages
    Good Essays
  • Satisfactory Essays

    Ilab Chemistry Lab

    • 451 Words
    • 2 Pages

    In order to measure the atomic weight of magnesium after it is consumed, it has to be mixed with hydrochloric acid. Once it has consumed it will produce hydrogen gas, which will be trapped and measured. This means that the atomic weight of magnesium will result from separating the hydrogen gas from the acid in the magnesium. The chemical equation mentioned in the introduction indicates that one mole of hydrogen gas is produced for every mole of magnesium that reacts. In this lab, there is a 1:1 ratio between the number of moles of hydrogen gas evolved and the number of moles of magnesium consumed in the reaction. Therefore, the number of moles of hydrogen gas evolved is equal to the number of moles of magnesium consumed. The atomic weight of magnesium is equal to the weight of magnesium consumed per moles of hydrogen gas evolved.…

    • 451 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    The experiment was done twice in trial 1 and 2. First, in the first trial, the crucible with lid was measured on a balance and the mass of them was recorded in grams which is m of clean crucible = 22.89g . This was followed by weighing the crucible with 0.3 g of Magnesium on a balance. The total mass of mg with the crucible was recorded which was m total mass mg + Crucible = 23.19g. Then the magnesium was heated using a Bunsen burner, and we put the crucible with Mg on a clay triangle using tongs in order to get MgO compound.…

    • 331 Words
    • 2 Pages
    Good Essays
  • Good Essays

    Massing Mg Lab

    • 1002 Words
    • 7 Pages

    To understand the change in mass after burning magnesium and to also determine the chemical formula of magnesium oxide…

    • 1002 Words
    • 7 Pages
    Good Essays
  • Satisfactory Essays

    Molarity Worksheet

    • 448 Words
    • 2 Pages

    4. A flask contains 85.5 g C12H22O11 (sucrose) in 1.00 liters of solution. What is the molarity?…

    • 448 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    This can be demonstrated by measuring the hydrogen gas evolved by performing a chemical experiment when hydrochloric acid reacts with the magnesium. The formulated reaction includes; Mg + 2HCl → H2 + Mg2+(aq) + 2Cl- (aq)…

    • 370 Words
    • 2 Pages
    Good Essays
  • Good Essays

    Farhampton Inn

    • 498 Words
    • 2 Pages

    one can calculate the mass of the oxygen that reacted with the magnesium. To obtain good results…

    • 498 Words
    • 2 Pages
    Good Essays
  • Good Essays

    Solubility is the amount of solid that can be dissolved in a certain amount of liquid at a certain temperature. In order for solubility to be tested, two trials were run. 5 mL of deionized water was measured and poured into a beaker. The temperature of the water was recorded. 2 grams of the unknown was measured out and placed into the same beaker as the deionized water. The unknown and water was then mixed well until the unknown was fully dissolved. Once the unknown was fully dissolved, small amounts of the solid unknown was then measured and mixed into the solution until the solution was either cloudy or had small amounts of solid unknown, unable to dissolved, at the bottom of the beaker. The solubility was then put into terms of moles per liter. Enthalpy change is the amount of heat that is released or absorbed in a chemical reaction at constant pressure. For enthalpy change to be calculated, 30 mL of deionized water was measured out and put in a coffee cup calorimeter. The initial temperature of the water was record. 1 g of the unknown was measured out. Fairly quickly, the unknown was added to the water and stirred. The LabQuest pad measured the change in the temperature of the water as the unknown was dissolved. Once 90 seconds had passed the heat trend was observed from the reaction. The enthalpy was calculated by using the formula, ∆H= c∙m∙∆T. The enthalpy change…

    • 1860 Words
    • 8 Pages
    Good Essays
  • Good Essays

    Mass Lab

    • 853 Words
    • 4 Pages

    Experiment one is in support of the conservation of energy pertaining to chemicals because heat energy was released when magnesium (Mg) and hydrochloric acid (2 HCl) to create magnesium chlorine (MgCl₂) and hydrogen (H₂). this reaction was exothermic because heat was produced in the process and released into the surroundings. The energy did not disappear in the reaction as it was clearly released from the substance. Therefore, the law of conservation of energy was in effect during the entirety of this…

    • 853 Words
    • 4 Pages
    Good Essays
  • Satisfactory Essays

    1. Identify the acid/base and their conjugate base/acid, and which definition you use to determine(Bronsted,…

    • 526 Words
    • 3 Pages
    Satisfactory Essays
  • Good Essays

    Lab Report

    • 347 Words
    • 2 Pages

    Abstract: The purpose of this lab was to see how magnesium reacts with oxygen. This reaction must be forced with heat. As magnesium changes to magnesium oxide the mass increased.…

    • 347 Words
    • 2 Pages
    Good Essays
  • Satisfactory Essays

    Molar volume is the volume that one mole of gas occupies when temperature and pressure are kept constant. The molar volume of a gas can be determined through evaluating how much gas is given off when the number of moles of the substance is known. To find the volume of gas that will be used to calculate the molar volume, the process of water displacement can be used.…

    • 1377 Words
    • 6 Pages
    Satisfactory Essays