Natural Indicators :: essays research papers

Natural IndicatorsEach year millions of tourists travel to the timber of New England, upstate New York, Wisconsin, and Canada to witness the appearance of brilliant declination colors. Sugar maples, inflammation oaks, sumac, birch and other trees and shrubs turn from green to glinting red, orange, and yellow. The short, cool days of autumn bring an end to the production of chlorophyl (the green light-gathering pigment). As chlorophyll gradually breaks down, the colors of the more permanent carotenoid (yellow/orange) and anthocyanin (red/blue/purple) pigments become visible. Some years the leaves of a particular species be bright yellow, while other years they whitethorn appear redder or even purple. Although no one can accurately predict the quantify or coloration of each years show, we do know that there is a chemical basis for it.Anthocyanins (Figure I) ar responsible not only for the red and purplish colors of autumn, but also for similar colors in various summer leaves ( red arise, red lettuce, red plum tree), flowers (roses, hydrangeas, geraniums, bachelor buttons, unsung pansies), fruit (cherries, red apples, grapes, tomato, blackberry, blueberry, plum), roots (beets, radishes), bulbs (red onions), and petioles (rhubarb). Anthocyanins are water-soluble and are change state in the cell sap rather than bound to the membranes as chlorophyll is. If cell sap in a leaf is very vitriolic, past anthocyanins make the leaves a bright red color, but if it is less acidic the color may appear purple. The color of anthocyanin depends on acidity, and thus it may serve as a pH (acid/base) indicator (Figure II). pH is a quantitative measure of the acidity or basicity of firmnesss. Numerically, the pH of a solution is defined as the negative logarithm (base 10) of the hydronium ion (H3O+) concentration. If the pH is less than 7 the solution is acidic, if it is greater than 7 the solution is basic, and if it is 7 the solution is neutral. The high the pH, the more basic the solution, and the lower the pH, the more acidic the solution. Figure II illustrates the relationship between color and pH for anthocyanin pigments extracted from red cabbage or other sources. Since anthocyanins are found in all of the above named constituent(a) materials, they are all very useful natural indicators. Natural indicators are better for detecting acids and bases than man made indicators. This experiment utilizes red cabbage juice, red onion juice, blueberry juice, phenolphthalein, bromythol blue, and universal indicator for the indicators and for the acids and bases, uses .