MHS Chemistry
Decomposition of a Carbonate

Many chemical compounds decompose when heated. Sometimes the result is the elements of which the compound was made, and other times it is simpler and more stable compounds. In this lab, you will use heat to decompose a carbonate compound into an oxide and carbon dioxide. You will also calculate the percent by mass of carbon dioxide in the compound.

  1. Weigh a clean, dry crucible to the nearest milligram.
  2. Record the name of the carbonate compound provided.
  3. Add no more than one gram of the carbonate compound to the crucible, and weigh them together. If you have too much, give a little extra to another group, or dispose of it in the waste container. DO NOT put it down the drain!
  4. Heat the sample over the hottest flame of the Bunsen burner for about ten minutes.
  5. Record the mass of the crucible and sample.
  6. Repeat steps 4 and 5 until the mass changes by less than 0.01 g.
  7. Dispose of the remaining sample in the waste receptacle, and clean your crucible


  1. Present all the information about your carbonate, including it’s identity, in a beautiful, clear, and proper data table.
  2. Determine the mass of the original sample.
  3. Determine the mass of carbon dioxide lost.
  4. Determine the percent carbon dioxide (by mass ) in the original sample.
  5. What happened to the missing mass? (In other words, where is it now?)
  6. Briefly describe some sources of error in the experiment (that are not mistakes in carrying out the procedure).

Each partner will pass in their own lab. The lab should be on exactly one sheet (this one will do). The lab is due on _______________.

[%CO2 in Carbonate Score Sheet][MHS Chem page]