Experiences

Chemistry opens doors

Mihaela Cucos

Romania

High Secondary School

Chemistry

Teaching in class, Laboratory

Direct

Chemistry can be a very interesting subject; it is at least for me, as a teacher; why not for my students as well? That is why I have tried to induce the same feeling in my students. I learned chemistry in the laboratory because chemistry it is an experimental subject. What can be more stimulating and more motivating for a student than carrying out a laboratory experiment? Chemistry opens doors to our innate curiosity and also provides us with answers. Experiments are memorable either by their visual nature or by testing theory. As a teacher I have tried to communicate the excitement and wonder of the subject I teach and I am interested in to my students so that they will want to take it further. It is a matter of communication: as a teacher you have to share your enthusiasm for your subject with your students in a simple way so that they will understand it. There is a lot of fun and learning in simple chemistry experiments and easy projects students can do to create really cool chemical reactions, which may whet their appetite for chemistry.
For instance they can make their own acid/base indicator by boiling red cabbage. They can use the resulting juice to pH different fluids. Ingredients: a red cabbage/ a greater/ acid/base solutions: for an acid try vinegar, for a base - mix some detergent in water. How to do the experiment: Ask students to grate the cabbage and put it in the pot + water; then they boil the liquid until it turns purple. Students will have to decant the fluid into a glass, then they will make up some acid/base solutions for the experiment: white vinegar; soda water/sprite or diluted juice from a lemon or orange; water +washing detergent. Students will have to add a few drops of the cabbage juice to your solutions, and note any color changes. The juice should turn pink in acidic solutions, and green in basic solutions.
Tell students they can use the indicator on any other solutions of interest, or try drying it on coffee filters to create a simple form of "pH paper." What is the explanation: red cabbage contains pigments called anthocyanins, which give it the red/purplish color. For most pH indicators, the compound acquires a proton at low pH (lots of H+) but looses it at higher pH. This creates the color change with respect to pH.