Figure 1) is inferior to that of the macroscopic demonstration (i.e. The effect of the microscale demonstration (cf. Consequently, in a large class of students, the only practical and applicable solution to the corresponding demonstrations is to use an overhead. black bubbles and black foam appear in the projected experiment), demonstrations (1) and (2) are almost ideal as overhead demonstrations. loss of color) and some minor distortions of the direct visual perception (e.g. ![]() Thus, despite some minor shortcomings (e.g. ![]() The results show that there are demonstrations where the mi- croscale version of the experiment combined with the use of an overhead projector give excellent results. 5) Aqueous solution of hydrogen peroxide with weight ra- tio (w) between 10% and 15% is added to aqueous solution of potassium iodide (KI) containing liquid detergent. ![]() The use of a vertical projection “Alyea-type” adaptor is vital (Phillips, 1988). A rapid growth of insoluble silicate(s) resulted, that can easily be followed on the screen during the “projection” of the experiment. A crystal of cobalt(II) nitrate was dropped in a test-tube filled with concentrated aqueous solution of sodium (meta)silicate (various crystals of water-soluble salts of transition metals may be used together).
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