Calorimetry 1: The Enthalpy of Formation of MgO Overview Getting Started Techniques Procedure FAQ Full Lab Manual Introduction & Goals Chemistry & Background Key Questions Prelab Problems Safety Procedure In Your Write-up Experiments Index ChemLab Home		HCl + NaOH Use a graduated cylinder to measure, as exactly as possible, 100 mL of 0.500 M HCl into a flask, and the same amount of 0.500 M NaOH into a second flask. Pour all the HCl into the calorimeter. Add a spin bar and replace the top plus the calorimeter thermometer. Allow the HCl to come to thermal equilibrium. When the acid in the calorimeter and the base in the flask have reached the same temperature, pour the base into the acid, stir gently with the thermometer, replace the cap, and record the exact time of mixing. Record the temperature every minute for approximately 10 minutes, using a magnifying glass and reading to +/- 0.01 °C. Plot temperature vs. time in your notebook as you record the data. Mg + HCl Use a ruler to measure a 10-15 cm length of magnesium ribbon. This should be about 0.10-0.12 g, which is approximately 0.005 mol. Scour the magnesium ribbon lightly with a nylon abrasive pad to remove any surface oxide. Weigh the ribbon to the nearest 0.0001 g, fold it in half, and wrap it completely (around the ends too) with a spiral of copper wire that has been formed around a pencil (10). Insert the ribbon into the wire spiral and flatten the spiral around it. The copper will not react; its purpose is to prevent the magnesium from floating to the surface. MgO + HCl Quickly add the MgO to the acid solution in the calorimeter, and replace the thermometer and cover. You should transfer the MgO as quantitatively as possible, without adding any additional water to the calorimeter.
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