Calorimetry: Lab Report
Part I: The Dissolving of Solid Sodium Hydroxide in Water
Procedure:
1. Measure out approximately 205 mL of distilled water and pour it into the calorimeter. Stir
carefully with a thermometer until a constant temperature is reached. Record the volume of
water and the constant initial temperature of the water on your data table.
2. Place a plastic measuring trough on top of the digital balance, and then zero the balance
(press the tare button) so that the mass of the trough will be "ignored" and will not be added
to the total mass measured by the balance.
3. Measure out approximately three to five scoops of solid sodium hydroxide and record the
mass to your data table.
4. Place the solid sodium hydroxide into the water in the calorimeter and replace the lid
immediately. Stir gently until the solid is completely dissolved and record the highest
temperature reached.
Data and Observations:
Calculations:
Equation for Chemical Reaction
NaOH (s) +H2O (l) —> NaOH (aq)
Number of moles of NaOH dissolved in the water
2.535 g NaOH * 1 mol NaOH / 39.997 g NaOH = 0.06338 mol NaOH
Calculating the amount of energy involved in this dissolving process.
-qNaOH = m × c × ΔT = 200 mL * 1g/1L * 4.184 J / (g × °C) * (27.8-24.2) °C = 3012.5 J
Determining the enthalpy change, per mole of sodium hydroxide dissolved
3012.5 J / 0.06338 mol NaOH = -475307 J * 1 kJ/1000 J = -47.53 kJ
Volume of Water
200.0 mL H2O
Mass of NaOH
2.535 g NaOH
Initial Temperature in Calorimeter
24.2 C
Final Temperature in Calorimeter
27.8 C
