Investigation of a Simple and Cheap Source of a Natural Indicator for Acid-Base Titration: Effects of System Conditions on Natural Indicators

This study investigated a natural indicator for acid-base titration which is extracted from guinea corn leaves popularly called “waakye leaves” in Ghana. Four types of acid-base titration were studied: strong acid versus (v/s) strong base, strong acid versus weak base, weak acid versus strong base, and weak acid versus weak base. The indicator color change, pH range and the average titre values were determined for each type of acid-base titration. These values were comparable to those obtained from three standard indicators: methyl orange, methyl red and phenolphthalein. Total flavonoids (TF) and condensed tannin (CT) from the crude leaves extract were determined which might be the major reasons for the activity of the extract as an indicator for simple acid-base titration. The authors suggest that the natural indicator is cheap, available, simple to extract, user and environmentally friendly and could be an excellent replacement for standard indicators.

异丙基萘系列导热油的合成与性能

一异丙基萘、二异丙基萘及三异丙基萘的热稳定性好，可再生，能长期在３３０～３５０℃的高温下运行，流动点低，使用方便，无腐蚀和不愉快气味，是一种优良的导热油。用天然硅铝酸催化丙烯对禁烷基化，在催化剂用量为８％、丙烯与萘的物质的量比为２：１及反应温度１５０℃、反应时间６ｈ的条件下，一、二及三异丙基萘的收率分别为５７．９％、２３．１％和１２．２％。