Evidence of Chemical Change Essay

Purpose To observe several chemical changes (reactions) and the evidence they exhibit for chemical change. Data See page 3 Analysis The two terms that describe possible energy change in a chemical reaction are Exothermic, for example when a gas is formed when Copper II Chloride and Aluminum are mixed, and Endothermic, for example when copper II Hydroxide is heated. There are many substances used in this experiment, the elements are Hydrogen Gas, Aluminum, and solid Copper, the compounds are Copper II Nitrate, Sodium Hydroxide, Copper II Hydroxide, Copper II Oxide, Hydrochloric Acid, Sodium Nitrate, H2O, Copper II Chloride, and Aluminum Chloride. In the last step of this experiment Aluminum Chloride is not a solid like it should be at room temperature, it is dissolved into the mixture. In order to recover the Aluminum Chloride as a solid, you would have to evaporate out all of the water. The color of the solution Copper II Nitrate is blue and the color of the solution Copper II Chloride is blue. Of all the substances listed in the second question, the ones that dissolve in water are Sodium Nitrate, Aluminum Chloride, Copper II Nitrate, Sodium Hydroxide, and Hydrochloric Acid, the substances that do not dissolve in water are Copper II Hydroxide, Copper II Oxide, solid Copper, Aluminum, and Copper II Chloride. These equations are written referring to the procedures in this experiment a) copper(II) nitrate + sodium hydroxide → copper(II) hydroxide + sodium nitrate b) copper(II) hydroxide (+ heat) → copper(II) oxide + H2O c) copper(II) oxide + hydrochloric acid → copper(II) chloride + H2O d) copper(II) chloride + aluminum → solid copper + aluminum chloride e) aluminum + hydrochloric acid → hydrogen gas + aluminum chloride Four general observations seen in this experiment that indicate a chemical change has occurred are color change, energy change, gas formed, and solid formed.