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Lab Experiment 3 9-20-07 revise

# Lab Experiment 3 9-20-07 revise - Ch 200-42 Experiment...

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9-20-07 Ch 200-42 Experiment Three Proving Dalton’s Law of Proportions Purpose:

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The purpose is to determine the heat of combustion of magnesium metal and contrast the results with theoretical values. Data and Calculations: Equations: Final 1. 2Mg + O2 -> 2MgO -601.2 Kj/mol -601.2Kj/mole 2. MgO + 2HCl -> MgCl2 +H2O 8.2 Kj/mol -16.4Kj/mole 3. Mg + 2HCl -> MgCl2 +H2 -306.6 Kj/mol -613.2Kj/mole 4. 2H2 + O2 -> 2H2O -571.6 Kj/mol -571.6 Kj/mole (eq.2) + (eq.3) + (eq.4) = (eq.1) Changes: Eq.2 Flip and multiply by two Eq.3 Keep and Multiply by two Eq.4 keep all Data:
Trial 1: 1. Mass of magnesium oxide: 1.00g 2. Volume 1M HCL : 100ml 3. Min. Temp: 26C 4. Max Temp.: 33C 5. Mean Temp: 31C 6. Temperature vs Time(ms) graph of the reaction. Calculations: 1. Change in temperature = (max temp)-(min temp) a. 33Cmax-26Cmin=7Cdifference 2. = * * q m c delta T a. Q=102.2*4.184*7 b. q=2993.23 joules 3. delta H = -q a. delta H=-2993.23/1000 b. delta H=-2.99323Kj 4. Moles MgO used = mass MgO used / Atomic Mass MgO a. 1g/40.011g=.025 moles MgO used 5. Delta H / Mole MgO a. -2.99Kj/.025moles =-119.73 kj/mole MgO 6.

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