Problem №10 «pH Indicator» Speaker:Artem Fursov Team Russia

The problem The juice of many fruits or vegetable crops contains a natural pH indicator that changes colors according to the acidity or basicity of the solution. Investigate such pH indicator juices and their mixes. Propose the most precise and effective composition and compare its properties with those of common indicator paper.

Goals: To analyze some juice for indicator To make standard solution with conventional pH To make analogy of litmus paper To analyze indicator mechanism of work in terms of anthocyanin

Choice of juice Make aqueous migrate from red cabbage, beet, pomegranate and red onion Analyze aqueous migrate for indicator

Analyze juice for change color in different values of pH

Change color Change color

Select of juice We select a red cabbage for indicator because we can repeatability results and we can determined visually results. Red cabbage has anthocyanin, which can change color.

Make a standard solution with conventional pH For our experiment we make solution series of acid and alkali with conventional stage of pH is 1

The final stage Put aqueous migrate from red cabbage in out solution with pH in diapason from 0 to 14 and watch color change of solution

Factors which effect to color Quantity of conjugate bonds Chromophores -NR3, -CN,- NO2 Auxochromes —ОН, —SH, NH2, C6H5O—

Our indicator scale is equal for litmus scale

Conclusions: In experiment we make analogy of litmus paper from juice of red cabbage We explore indicator mechanism of work in terms of anthocyanin

Thank you for your attention