"Dancing Currants" Return to list of pracs

Aim: To observe the movement of sultanas (or preferably currants) by adding bicard of soda to vinegar.

Equipment: The equipment includes...  

• currants;
• icecream container (or preferably a tall glass);
• vinegar;
• bicarb of soda.

Method: Pour vinegar into the container, add sultanas and observe any movement. Add bicard of soda and report on observations.

Background knowledge: Why does the bicard of soda assist in thr movement of currants? Small groups work better. A tall glass can make the movement up and down more apparent. The reaction is an acid-base reaction (the vinegar is acetic acid) and the base is sodium carbonate. The release of carbon dioxide gas occurs. This is the gas you get in an fizzy drinks (eg. cola cola etc). These bubbles form and attach themselves to the currants and after time increase in size to a point where they then become bouyant enough the raise the currant to the surface of the liquid. They then burst and the weight of the currant drops it back down to the floor of the container. It then repeats over and over. The currants should appear to rise and fall all the time.