Indicadores naturais de pH: usar papel ou solução?

In this work, the fruit extracts of Morus nigra - mulberry, Syzygium cuminii - jambolão, Vitis vinifera <FONT FACE=Symbol>¾</FONT> grape, Myrciaria cauliflora - jabuticaba are suggested as pH indicators in the form of either solutions or paper. The pH indicator solutions were prepared by soaking the fruits or their peels in ethanol 1:3 (m/V) for 24 h, followed by simple filtration. The pH indicator papers were prepared by imersion of the qualitative filter paper strips in the pH indicator solutions. The different pH leads to color changes in the indicator solutions or papers and it can be used for teaching elementary chemistry concepts.