Copper Compounds Lab

Identification of a Copper Compound by Percent Mass

Unknown Compound: #9

Abstract:

The objective of this experiment was to identify the unknown pure copper salt compound of #9. To do this, the mass of copper in the unknown was calculated and then divided by the mass of the whole compound to get the percent copper. The molecular weight was also calculated by dividing mass of copper compound used by moles of compound in unknown sample. The percent copper averaged out to 31.6% while the molecular weight of the sample averaged out to 201.1mw. In conclusion, the unknown compound of pure copper salt was close to Cu(C2H3O2)2 •H2O which has a percent copper of 31.8% and a molecular weight of 199.654mw.

Introduction:

What is the unknown
The copper in the compound needed to be dissolved by using hydrochloric acid and then react with magnesium in order to only get copper left in the solution at the bottom of the beaker. The copper should be weighed and then compared with the other compounds (Table 2) in order to find the unknown. This was all performed in the
|Mass of watch glass |25.6447g |32.8348g |
|Mass of dried materials, watch glass and paper |26.5053g |33.6947g |
|Mass of elemental copper obtained |0.6237g |0.6267g |
|Moles of elemental copper |0.0098m |0.0099g |
|Moles of unknown compound |0.0098m |0.0099m |
|Percent mass of copper |31.1% |32.2% |
|Molecular Weight of compound |204.8mw |197.4mw |

Equation 1:

(Mass of dried copper + mass of watch glass + mass of filter paper) – (Mass of filter paper) – (Mass of watch glass) = (Mass of elemental