SBI, temperature probe, 400 mL beaker, magnetic stir bar, stir plate, small 3 finger clamp and ringstand.
33.3 mL of 3 M hydrochloric acid, 8.4 g of NaHCO3.
Logger Pro settings: Use a temperature range of 10-25 °C, collect data for 100 seconds at a rate of 2 samples per second.
- Add the NaHCO3 to the beaker, place the stir bar in the beaker.
- Place the beaker on the stir plate. Some insulating material between the beaker and the stir plate is helpful.
- Clamp the temperature probe to the ringstand, lower the probe into the beaker until it is almost touching bottom. Place the probe so that it is to the side, out of the way of the stir bar.
- Connect SBI to the computer.
- Start Logger Pro program and set parameters.
- Start data collection.
- Add hydrochloric acid slowly to the beaker, so that the reaction does not overflow the beaker.
Note: Remove the temperature probe from the solution as soon as data collection is complete and rinse with DI water.
Hydrochloric acid can irritate the skin. Hydrochloric acid vapors are extremely irritating to the eyes and respiratory system. Therefore, it should be handled only in well-ventilated area.
The standard state enthalpy of the following reaction is +28.5 kJ mol.-1
The standard state Gibb's free energy is -41 kJ mol-1. Since the reaction is spontaneous, it must be entropy driven. This intuitively makes sense because one of the reactants is a solid and one of the products is a gas, so the overall entropy has increased. A calculation reveals the entropy increase to be 230 J mol-1 K-1.NaHCO3 (s) + H+(aq) ® Na+(aq) + CO2 (g) + H2O (l)