Teaching Tip: Acid-Base Titration Experiment

Name:

Cheng-Hung Shih 

Economy:

Chinese Taipei

School:

Hui Wen Elementary School

Subject:

Science

Tip:

This experiment tries to use a commonly seen purple cabbage concentration as the indicator for titration, and tests the acid-base results of several solutions.

First, the teacher minced the purple cabbage and put the slices into a flask, and then put some water in it, heat it for 15 minutes with an alcohol lamp, and we have the perfect indicator.

Second, the teacher prepared each solution with 50 ml. For example, the teacher chose soda, soap, salt, sugar and coke.

One thing needs to be mentioned is that the teacher used a syringe to take the solution, instead of using burette or flask. The advantages of the syringe are: it sucks the solution quickly, easily and accurately. And students don’t need to wash and clean every burette or flask so often.

Last but not least, the teacher showed the whole class the results by letting students do the experiment and witness the color changes. All students saw the acid solutions turned red, base solutions turned green, while the neutral solutions stayed purple when mixing with the purple cabbage concentration. The outcome was presented on the blackboard as follows:

To sum up, it’s a safe and fun experiment, and students really enjoy DIY (making their own solutions) very much!