This experiment called for numerous testing, using a variety of different laboratory tools in addition to a few different substances and materials to perform reactions with. The first experiment (Reaction A), which was performed to become familiar with a synthesis reaction, involved the use of magnesium ribbon and heat provided by a laboratory burner. The magnesium ribbon was placed a crucible while the laboratory burner was in use. Forceps were used to hold the magnesium ribbon while the reaction was occurring. The experiments involving the decomposition, single displacement, and double displacement all revolved around the same materials: two test-tubes, a rubber stopper, a ring-stand, rubber tubing, and a glass bend.
Reaction B, which was an example of a decomposition reaction, involved pouring clear soda water into a test-tube, and then gently shaking the tube. Continuing with the same material from the decomposition reaction, Reaction C calls for covering the test tube with clear soda water with a one-hole stopper. Through the hole, a glass bend was inserted, connected to a rubber tube extending to a test tube filled with about 5 mL of saturated calcium hydroxide. Like in Reaction B, it was necessary to shake the test tube to yield the reaction. Following Reaction C, we needed to rinse and clean the test tubes in preparation for Reaction D, a single displacement reaction. Initially, 10 mL of hydrochloric acid was placed in a test tube. Using the same stopper and tube setup, a rubber tube extended to an inverted test tube with tap water, placed in a beaker of tap water. A piece of magnesium ribbon was dropped into the test tube containing the hydrochloric acid. After the reaction occurred, the tubes containing gas were stoppered, and removed out of the water in the same inverted position. For Reaction E, which displays a synthesis reaction, a burning splint was brought to the mouth of the gas-filled test tube. Finally, Reaction F, a double displacement reaction, involved the mixture of hydrochloric acid and silver nitrate.
Results and Observations
Table 1. Results of Chemical Reactions
Table 2. Word Equations for Reactions
Table 3. Balanced Equations for Reactions
Discussion
In this lab, we were exposed to displays of four different types of chemical reactions. From the data gathered, we learned the similarities and differences between these four reactions, as well as their effects and characteristics. In a synthesis reaction, two simple substances form a compound. In Reaction A, we saw how the combination of magnesium, oxygen, and heat from the burner yielded a reaction –the flickering light. We saw the decomposition of a compound in Reaction B, were the club soda resulted in water and carbon dioxide after shaking the test tube to release the carbon dioxide from the substance. Reaction D, a single displacement reaction, demonstrated the effect of hydrochloric acid and magnesium –a “burning” of the magnesium resulting in a solitary transfer of hydrogen gas. A double displacement reaction occurred in Reaction F, when silver nitrate and hydrochloric acid were combined, yielding a newly formed white solid. The rearrangement and transaction of these substances formed silver chloride and nitric acid.
Synthesis, decomposition, single displacement, and double displacement reaction all differ in the way molecules are rearranged and transferred –however, all of these reactions share the concept of change. A reaction can range from a simple combination of water oxygen to a complex formula involving unstable substances –the constant in these experiments is that the reaction occurs because the make-up of the substance is changed. From this, I can not only understand better the constant reactions that occur around me at every second of my life; I can evaluate them and realize why they happen.
Questions
What type or types of reactions cannot involve a free element as a reactant? Why?
A double displacement reaction cannot involve a free element as a reactant. In a double displacement reaction, both products are reversed, which closes the possibility of a free element being a reactant.
Using oxygen, hydrogen, and water, write balanced equations to demonstrate that decomposition is the reverse of synthesis.
Synthesis: 2H2 + O2 → 2H2O
Decomposition: 2H2O → 2H2 + O2
In the synthesis reaction, the hydrogen and oxygen are combined to form H2O, or water. Oppositely, this water can be broken down from H2O to hydrogen and oxygen.
How do single displacement reactions differ from double displacement reactions?
A single displacement reaction involves the replacement of only one product in the equation. However, double displacement reactions involve a transaction of two sets of products.