Exercise 1: Gas and Reactions Data Table 1. Gas Observations.
Step/Reaction
Observations
Reaction between zinc and hydrochloric acid
Hydrogen Gas + Flame
Reaction that occurs when magnesium is in contact with hydrogen peroxide
Oxygen Gas + Smoldering toothpick
Gas Mixture + Flame
A) Write a balanced chemical equation describing the reaction of zinc and hydrochloric acid?
B) What gas was produced by the reaction of zinc and hydrochloric acid? How did this gas behave in the presence of fire?
C) What gas was produced by the decomposition of hydrogen peroxide? What happened when the smoldering toothpick came in contact with the gas?
D) Compare the behavior of the mixture of gases with each solitary gas in the presence of flame?
E) Outline the procedures you would use to determine whether a gas sample was composed of hydrogen or oxygen?
Exercise 2: Gas and Reactions
Data Table 2. Carbon Dioxide Reaction Observations.
Step/Reaction
Observations
Reaction between Ca(OH)2 and CO2
Reaction between CO2 and BTB
Carbon Dioxide Gas + Flame
Reaction between Ca(OH)2 and Alka-Seltzer® + water gas
Alka-Seltzer®/ Water Gas + Smoldering toothpick
Reaction between Ca(OH)2 and Breath
F) The chemical equation for the reaction of baking soda (sodium bicarbonate, NaHCO3) and vinegar (acetic acid, CH3COOH) may be written as two steps. Fill in the missing information for the chemical equation.
Step 1: + ® CH3COONa(aq) + H2CO3(l)
Step 2: H2CO3(l) ® H2O(l) + .
G) Write a chemical equation for the reaction of CO2 and limewater (Ca(OH)2). Write a physical description of the products formed.
H) When the bromothymol blue (BTB) was exposed to the CO2 gas, what color was the solution? Did the BTB indicate presence of an acid or base? Explain.
I) Did the reaction between the Alka-Seltzer® and the tap water produce hydrogen, oxygen, or carbon dioxide gas?
J) Based on your observation of the reaction that occurred when limewater was exposed to your breath, what gas did you exhale?
K) In 1766, Henry Cavendish became the first scientist to isolate hydrogen. To do so, Cavendish placed a variety of metals in acid. Which of the reactions in this experiment (Exercises 1 and/or 2) most closely mimics Cavendish’s methods?