Chemistry 11 |
The Decomposition Reaction of Baking Soda, NaHCO3 |
Oscar ShiPeriod 2Laboratory AssignmentDue Date: 2011/4/14 |
The objective of this experiment is to find the actual chemical equation that governs the manner in which baking soda (sodium hydrogen carbonate NaHCO3) decomposes.
When NaHCO3 is heated, it decomposes to produce a gas and leaves behind a solid. Two possible equations for the decomposition are:
NaHCO3 (s) + heat NaOH (s) + CO2 (g)
NaHCO3 (s) + heat ½ Na2OH3 (s) + ½ H2O (g) + ½ CO2 (g)
Materials and Methods
* electronic balance
* sodium hydrogen carbonate
* ring stand
* crucible tongs
* crucible lid
* clay triangles
The Procedure of the Laboratory
1. Put on safety goggles and a lab apron.
2. Obtain a clean and dry crucible and lid. Crucibles very slowly adsorb small amounts of water vapour from the atmosphere and must be heated for a minute or two to get rid of adsorbed water molecules before you can get an accurate “initial mass” for a crucible. Crucibles are usually heated in clay triangles, which in turn are set on top of rings attached to ring stands.
3. Hot crucibles can blister your bench top, so hot crucibles should be placed on the steel base of your ring stand using your crucible tongs at all times in order to cool down.
4. After the crucible has cooled down, accurately determine the mass of your crucible. Record this mass on your date sheet. If a very hot crucible is put on an electronic balance, the balance can be ruined.
5. Put about 5.00 g of sodium hydrogen carbonate in the cool crucible. Once again using the electronic balance, record the mass of the crucible plus baking soda accurately on your data sheet. Using the method of mass by difference, figure out the mass of the sample and enter this into your data sheet.
6. In order to decompose, sodium hydrogen carbonate must be heated until the crucible starts to glow an...