1. Experiment
   1. Heat 1.25 g of copper chloride hydrate in a crucible. After heating and then cooling, the final mass is 0.986 g of copper chloride, Cu_xCl_y.
   2. Dissolve the Cu_xCl_y sample in 50 mL of deionized water and add 0.2 g of fine aluminum mesh to the beaker.
   3. After reacting and dissolving the excess aluminum, 0.198 g of dried copper metal is recovered.
   4. Subtract the mass of both copper and water from the initial copper chloride hydrate to yield&#

In one example, suppose an unknown biomolecule containing only C, H, and O is found to act well as a new fuel. One way to determine the formula of the fuel would be to combust it in air and analyze the products:

C_xH_yO_z + O₂ → mCO₂ + nH₂O

While O₂ is in excess, we would know all the carbon in CO₂ originated from the biomolecule and all the hydrogen would be present in H