Experiment of alkaline hydrolysis of ethyl acetate
Experimental background
The beauty of chemistry lies in exploring the change of matter and analyzing its mechanism to reveal the wonder of creation. Today, the alkaline hydrolysis of ethyl acetate is an important case of chemical kinetics research.
Experimental principle
Ethyl acetate ($CH_3COOC_2H_5 $) reacts when it meets a base (such as sodium hydroxide $NaOH $). The reaction formula is as follows:
$CH_3COOC_2H_5 + NaOH\ longrightarrow CH_3COONa + C_2H_5OH $
This reaction is a second-order reaction, and its rate is related to the concentration of ethyl acetate and sodium hydroxide. During the reaction process, the reaction rate can be inferred by measuring the change in the concentration of a substance.
Experimental Materials and Instruments
1. ** Materials **: ethyl acetate, sodium hydroxide, phenolphthalein indicator, distilled water.
2. ** Instruments **: thermostatic tank, pipette, conical bottle, alkaline burette, stopwatch.
Experimental Steps
1. ** Prepare the solution **:
- Prepare a certain concentration of sodium hydroxide solution in a precise way and place it in a clean reagent bottle.
- Measure an appropriate amount of ethyl acetate and set aside.
2. ** Thermostatic treatment **:
- Adjust the thermostatic tank to the specified temperature, such as 25 dollars ^ {\ circ} C $.
- Put the conical flask containing the sodium hydroxide solution and ethyl acetate into a thermostatic tank and let it stand for a while to achieve thermal equilibrium.
3. ** The reaction begins **:
- Take a certain volume of ethyl acetate accurately with a pipette and quickly pour it into the conical flask containing the sodium hydroxide solution. At the same time, start the stopwatch to record the reaction start time.
- Quickly shake the conical flask to mix the two thoroughly.
4. ** Sampling titration **:
- At specific time intervals, such as 5 dollars $minutes, 10 dollars $minutes, 15 dollars $minutes, etc., a certain volume of solution is pipetted from the reaction mixture and injected into a conical flask pre-filled with an appropriate amount of distilled water to terminate the reaction.
- A few drops of phenolphthalein indicator are dropped into this conical flask, and the solution is red.
- With a standard solution of hydrochloric acid of known concentration, it is titrated through an alkaline burette until the red color of the solution just fades, and the volume of hydrochloric acid consumed is recorded.
Experimental data recording and processing
1. ** Record Data **: Carefully record the volume of hydrochloric acid consumed for each sampling titration and the corresponding reaction time in the table.
| Reaction time (min) | Volume of hydrochloric acid consumed (mL) |
|---|---|
| 5 |... |
| 10 |... |
| 15 |... |
2. ** Data Processing **:
- Calculate the concentration of sodium hydroxide in the solution at different times according to the volume of hydrochloric acid consumed, combined with the reaction equation and the relevant stoichiometric relationship.
- A straight line can be obtained by plotting the reciprocal of the sodium hydroxide concentration against the reaction time. From the slope of the straight line, the reaction rate constant can be obtained.
Experimental Conclusion
Through this experiment, we can understand the relationship between the reaction rate of alkaline hydrolysis of ethyl acetate and the concentration and temperature of the reactants. Through precise operation and data processing, the rate constant of the reaction at a specific temperature is known, which is of great significance for in-depth understanding of the kinetic mechanism of chemical reactions. And this experiment also provides a reference for the study of many reactions in the field of chemistry.
