Determination of a Chemical Formula

Ethan Trevino, Corbet Johnson & Browning Becherer

Lab Description

In this lab we determined the weight of water in a copper chloride hydrate sample and conducted a reaction between a solution of copper chloride and an aluminum wire. Then we used these results of the reaction to determine the ,ass and moles of Cu and Cl in the solution, and finally we calculated the empirical formula of the copper chloride compound after the reaction.


  • Mass of crucible: 13.54g
  • Mass of crucible and hydrated sample: 14.54g
  • Mass of hydrated sample: 1g
  • Mass of crucible and dehydrated sample: 14.28
  • Mass of water evolved: .74g
  • Mass of empty paper: .26g
  • Mass of paper and copper: .95g
  • Mass of copper: .42g

Data Analysis

How many moles of water were in your sample of copper chloride hydrate?

1.44 *10^-2 mole H2O

How many moles of copper were in your sample of copper chloride?

6.6 * 10^-3 mole Cu

How many moles of chlorine were in your sample of copper chloride?

1.35 * 10^-2 mole Cl

Proper chemical formula for the compound is.

CuCl2 * 2H2O

Sources of Error

Throughout the experiment, the errors would have come from human mistakes that are unavoidable. For example, we could've slightly mis-measured something here or overheated something there. There were not any major, experiment-threatening mistakes.