International University, Vietnam National University - HCMC CHEMISTRY LABORATORY
Instructor: Ngo Nguyen Tien Dat, MSc
KEY TO PRE-LAB 4 – CHEMICAL EQUILIBRIUM
1. What is a reversible chemical reaction? Give at least 1 example of a reversible
chemical reaction. (5 pts)
A reversible reaction is a chemical reaction where the reactants form products that, in
turn, react together to produce the reactants. (3 pts)
Correct reversible reaction. (2 pts)
2. How do we define the equilibrium point of a reversible reaction? (5 pts)
Assuming that the reversible reaction happens in a closed system, the reversible
reaction will reach equilibrium when:
- The concentrations of the reactants and the products do not change. (2.5 pts)
- The rates of the forward reaction and the reverse reaction are similar to each other. (2.5 pts)
3A. Write the formula for hydrochloric acid. Where can one obtain concentrated
hydrochloric acid for experiment 2.4? (5 pts)
- The formula for hydrochloric acid: HCl (2.5 pts)
- Solution of concentrated hydrochloric acid is placed in the fumehood. (2.5 pts)
3B. Write the formula for cobalt chloride. Where should one dispose solution
containing cobalt ions after the experiment? (5 pts)
- The formula for cobalt chloride: CoCl2 (2.5 pts)
- Solution containing Co2+ ions should be disposed in the toxic waste beaker after the experiment. (2.5 pts)