Chem Lab - Heat of Combustion of Magnesium

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Heat of Combustion of Magnesium

Background: The students were given full instructions on how to experimentally determine the enthalpy of reaction (ΔHrxn) for the combustion of magnesium ribbon, using Hess’s Law.

Data Collection:
| |Reaction 1 |Reaction 2 | | |(MgO) |(Mg) | | |Trial 1 |Trial 2 |Trial 1 |Trial 2 | |Volume of 1.00 M HCl |50.0 mL ± 0.5 mL |50.0 mL ± 0.5 mL |50.0 mL ± 0.5 mL |50.0 mL ± 0.5 mL | |Final temperature, t2 |28.9(C ± 0.1(C |28.8(C ± 0.1(C |44.8(C ± 0.1(C |44.4( C ± 0.1(C | |Initial temperature, t1 |22.5(C ± 0.1(C |22.3( C ± 0.1(C |21.9(C ± 0.1(C |21.8( C ± 0.1(C | |Mass of solid |0.50 g ± 0.01g |0.50 g ± 0.01g |0.25 g ± 0.01g |0.25 g ± 0.01g |

Data Processing:
| |Reaction 1 | | |(MgO) | | |Trial 1 |Trial 2 | |Change in |final temperature – initial temperature |final temperature – initial temperature | |temperature, (t |28.9(C – 22.5(C = 6.4(C |28.8(C – 22.3(C = 6.3(C | | | | | | |Uncertainty of temperature: 0.1(C + 0.1(C = 0.2(C |Uncertainty of temperature: 0.1(C + 0.1(C = 0.2(C | | | | | | |Change in temperature = 6.4(C ± 0.2(C |Change in temperature = 6.3(C ± 0.2(C | |Heat of HCl |Mass of 1.0 M HCl [pic] specific heat of HCl [pic] change in |Mass of 1.0 M HCl [pic] specific heat of HCl [pic] change in | |solution, q |temperature |temperature | | | | | | |To find mass of 1.0 M HCl : Density of 1.0M HCl [pic] volume |To find mass of 1.0 M HCl : Density of 1.0M HCl [pic] volume | | |of 1.0M HCl |of 1.0M HCl | | |1.005 [pic] [pic] 50.0 mL = 50.3 g |1.005 [pic] [pic] 50.0 mL = 50.3 g | | | | | | |50.3 g [pic] .00418 [pic] [pic] 6.4(C = 1.3 kJ |50.3 g [pic] .00418 [pic] [pic] 6.3(C = 1.3 kJ | | | | | | |% Uncertainty of Heat: [(0.5mL ÷ 50 mL) + (0.2(C ÷...
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