PURPOSE: The purpose of this lab is to determine the molar enthalpy of combustion (ΔHCOMB) of Magnesium. Mg + ½O2 → MgO This reaction is too dangerous to carry out directly to measure the enthalpy Dangers of Burning Magnesium. Instead of carrying out this target reaction directly we will be carrying out two of the known reactions (1 & 2) and the 3rd known reaction value is also too dangerous to carry out so its value is given. TARGET: Mg(s) + ½O2(g) → MgO(s) ΔH = KNOWN EQUATIONS: 1) Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) ΔH = kJ 2) MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l) ΔH = kJ 3) H2(g) + ½O2(g) → H2O(l) ΔH = -285.8 kJ Two experiments will be carried out using calorimetry to determine the ΔH for Reaction 1 & Reaction 2. EXPERIMENT # 1 Experiment #1 (Known Reaction 1 above) Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) will be carried out using calorimetry. A certain mass of Mg will be added to a certain volume of HCl. The AQUEOUS solution of HCl is very DILUTE so we will consider it WATER for our calculations.Once the Mg is placed in the HCl the t1 will be taken and once the reaction is over (the temperature stops changing) the t2 will be taken. Watch this video link for Experiment 1 and enter the data into the observation table. (4 marks) Mass of Mg g Mass of HCl (mL=g) g t1 oC t2 oC * Remember HCl is going to be considered H2O CALCULATIONS FOR EXPERIMENT #1 Use the data above and calculate the molar enthalpy (ΔHx) of the reaction in terms of Mg. HINT you need to do the 2 steps for this calculation ΔH = mcΔt & ΔH = nΔHx and this answer will be your ΔH value for your KNOWN equation #1. The video mentions figuring out the Limiting Reagent but it is Mg that you are calculating in terms of. (6 marks) EXPERIMENT # 2 Experiment #2 (Known Reaction 2 above) MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l)will be carried out using calorimetry. A certain mass of MgO will be added to a certain volume of HCl. The AQUEOUS solution of HCl is very DILUTE so we will consider it WATER for our calculations.Once the MgO is placed in the HCl the t1 will be taken and once the reaction is over (the temperature stops changing) the t2 will be taken. Watch this video link for Experiment 2 and enter the data into the observation table. (4 marks) Mass of MgO g Mass of HCl (mL=g) g t1 oC t2 oC * Remember HCl is going to be considered H2O CALCULATIONS FOR EXPERIMENT

Question

PURPOSE: The purpose of this lab is to determine the molar enthalpy of combustion (ΔHCOMB) of Magnesium. Mg + ½O2 → MgO This reaction is too dangerous to carry out directly to measure the enthalpy Dangers of Burning Magnesium. Instead of carrying out this target reaction directly we will be carrying out two of the known reactions (1 & 2) and the 3rd known reaction value is also too dangerous to carry out so its value is given.

TARGET: Mg(s) + ½O2(g) → MgO(s) ΔH = KNOWN EQUATIONS:
1) Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) ΔH = kJ
2) MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l) ΔH = kJ 3) H2(g) + ½O2(g) → H2O(l) ΔH = -285.8 kJ Two experiments will be carried out using calorimetry to determine the ΔH for Reaction 1 & Reaction 2.

EXPERIMENT # 1 Experiment #1 (Known Reaction 1 above) Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) will be carried out using calorimetry. A certain mass of Mg will be added to a certain volume of HCl. The AQUEOUS solution of HCl is very DILUTE so we will consider it WATER for our calculations.Once the Mg is placed in the HCl the t1 will be taken and once the reaction is over (the temperature stops changing) the t2 will be taken. Watch this video link for Experiment 1 and enter the data into the observation table. (4 marks) Mass of Mg g Mass of HCl (mL=g) g
t1 oC t2 oC

*** Remember HCl is going to be considered H2O

CALCULATIONS FOR EXPERIMENT #1 Use the data above and calculate the molar enthalpy (ΔHx) of the reaction in terms of Mg. HINT you need to do the 2 steps for this calculation ΔH = mcΔt & ΔH = nΔHx and this answer will be your ΔH value for your KNOWN equation #1. The video mentions figuring out the Limiting Reagent but it is Mg that you are calculating in terms of.
(6 marks)

EXPERIMENT # 2 Experiment #2 (Known Reaction 2 above) MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l)will be carried out using calorimetry. A certain mass of MgO will be added to a certain volume of HCl. The AQUEOUS solution of HCl is very DILUTE so we will consider it WATER for our calculations.Once the MgO is placed in the HCl the t1 will be taken and once the reaction is over (the temperature stops changing) the t2 will be taken. Watch this video link for Experiment 2 and enter the data into the observation table. (4 marks) Mass of MgO g Mass of HCl (mL=g) g
t1 oC t2 oC

*** Remember HCl is going to be considered H2O

CALCULATIONS FOR EXPERIMENT

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Solution 1

#2 Use the data above and calculate the molar enthalpy (ΔHx) of the reaction in terms of MgO. HINT you need to do the 2 steps for this calculation ΔH = mcΔt & ΔH = nΔHx and this answer will be your ΔH value for your KNOWN equation #2. The video mentions figuring out the Limiting Reagent but it is MgO that you are calculating in terms of.
(6 marks)

CALCULATIONS FOR TARGET REACTION Now that you have the ΔH values for the known reactions 1 and 2, you can calculate the ΔH for the target reaction. Use Hess's Law to add and subtract the known reactions to get the target reaction. Remember, you can flip the reactions (which changes the sign of ΔH) and multiply the reactions by any factor to get the correct stoichiometry. Once you have the target reaction, add the ΔH values of the manipulated reactions to get the ΔH for the target reaction. (4 marks)

CONCLUSION Write a conclusion about your findings. Discuss the accuracy of your results and any sources of error. (2 marks)

This problem has been solved

Solution 2

CALCULATIONS FOR TARGET REACTION Now that you have the ΔH values for the known reactions 1 and 2, you can calculate the ΔH for the target reaction. Use Hess's Law to add and subtract the known reactions to get the target reaction. Remember, you can flip the reactions (which changes the sign of ΔH) and multiply the reactions by any factor to get the correct stoichiometry. Once you have the target reaction, add up the ΔH values of the manipulated known reactions to get the ΔH of the target reaction. (6 marks)

CONCLUSION Write a conclusion about your findings. Discuss the accuracy of your results and any sources of error. Also discuss the implications of your findings for the combustion of magnesium. (4 marks)

This problem has been solved

Similar Questions

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Magnesium metal reacts with hydrochloric acid according to Reaction 1.Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)Reaction 1During an experiment to measure the molar enthalpy ΔH° of Reaction 1, a student placed 100. mL of dilute HCl(aq) into a coffee cup calorimeter, as shown in Figure 1.Figure 1 Coffee cup calorimeterAfter monitoring the solution temperature for 1 min, 0.486 g of Mg(s) was then added to the solution inside the calorimeter and stirred while continuing to monitor the temperature until the Mg(s) was completely consumed. The results of the experiment are shown on the graph in Figure 2.Figure 2 Graph of temperature versus time during the reaction of magnesium with hydrochloric acidAccording to the first law of thermodynamics, the heat produced (or consumed) by a reaction qrxn must be equal to the heat transferred to (or taken from) the surroundings (ie, the solution and the calorimeter), as expressed by Equation 1.−qrxn = qsurroundings = qsolution + qcalorimeterEquation 1 Question 41Based on the results of the calorimetry experiment described in the passage, the magnitude of the molar enthalpy ΔH° for Reaction 1 (in kJ/mol Mg) is closest to which of the following? (Note: Assume that the HCl(aq) has a density of 1.0 g/mL and a specific heat capacity of 4.0 J/(g∙°C), and that qcalorimeter ≈ 0.)A.8.84B.18.2C.442D.844

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