There are hundreds of acid-base indicators pH, that were synthesized from the mid nineteenth century. Some of them can be found in the school of chemical laboratory. Indicator methyl orange pH is red in the acidic solution, is orange in neutral solution and is yellow in the alkaline.
Indicator thymol blue has more vivid colors characteristic: it is crimson red in the acidic solution, is yellow in neutral and blue in the alkaline.
pH Indicator phenolphthalein (it is sold in a pharmacy called "Purgen") is colorless in acid and neutral environment.
But color of it indicator in an alkaline solution is crimson. Therefore, the phenolphthalein is used only to determine the alkaline solutions.
Depending on pH of the solution brilliant green dye changes the color (it alcohol solution is used as a disinfectant "greenery").
To check this, we must prepare a dilute solution of brilliant green: pour in a test tube a few milliliters of water and add one or two drops of pharmacy drug. The solution will get a beautiful green-blue color. In acid color changes to yellow, and in alkaline color will disappear (the solution will be transparent).
However, the most commonly used generic indicator pH in laboratory practice, as is a mixture of several acid-base indicators.
How to make indicator pH
How to make indicator pH? Do so.
Some of the substances, that we use in food, can replace indicator pH, is used in chemical laboratories.
1 way: How to make a pH indicator from black currant juice
Cut paper into several thin pieces (1 x 5 cm is fine), paper will be white.
Dip the pieces of paper in a fresh currant juice, - leave it for 5-6 minutes, soaked. Then You need to extract them from the juice and allow to dry. When dry indicator pH will be ready.
Let's try its action. To do this, one of our indicator pH dip in the solution of soda ash. You can also use ammonia. Our indicator pH will change color to blue-green (becouse all solutions of soda ash and ammonia are alkaline!)
And now take a new indicator pH and put drop of vinegar or lemon juice on it. Color change on a bright red!
Soda ash(or sodium carbonate)– Na2CO3 – white powder used in household for cleaning and washing. This substance is perfectly dissolves in water, forming a strong alkaline solution. Solution of sodium carbonate boiling cleans even the dishes with burnt food. You should not to work with it solution without gloves, because it has large chemical activity.
Persol. This is a complex substance - salt, the main part of which is linked sodium carbonate and hydrogen peroxide in a single moleculeе 2Na2CO3*3H2O2. The chemical name of this complex substance is peroxocarbonate sodium is complex solt. This is a white small crystals. When the heating it, this substance is decompose and releasing oxygen and is turned sodium carbonate (washing soda (sod ash) Na2CO3) and water. Persol good, because it does not damage the paint. Using parsoli easily cleared stains from tea, coffee, fruit, grease.
Baking soda (or sodium bicarbonate) – NaHCO3 – similar to soda ash and has difference only one atom of sodium.
In soda ash atoms have were replaced all atoms of hydrogen, as in baking soda - "sodium atoms were not enough".
Baking soda is not dangerous for consumption.
Use baking soda for washing dishes, especially well this salt washes brown plaque (tannic acid), left after drinking tea in cups. Baking soda is much less soluble in water than soda (washing) soda, and, in difference form last, gives a very weak alkaline reaction
2 way:
The same way you can cook to make a indicator pH of mulberry juice. This indicator pH also respond well to acid or alkali.
Also the indicator can be as onion broth, but the indicator pH, produced on its basis, has less bright paint and especially not indicative.
If desired, you can try the effect of these indicators on other solutions: washing powders, soap, liquid ammonia, soda water, etc
If the solution has expressed pH (less or more than 4 on a scale pH), each time our indicator pH will change color somewhere more, somewhere less - depending on the activity solution.
3 way:
How to make a pH indicator of Aronia juice. Color indicator pH will change from purple to blue or blue depending on the pH of the solution. Anthocyanin dyes, that have the properties of indicators, give purple color.
They are purple in acid solution and blue in neutral or alkaline.
If a few drops of Aronia juice to dissolve in a glass of soda solution, then it color becomes blue.
Our indicator pH will be purple, if it is placed in acid medium (such as vinegar or citric acid).
4 way
How to make a pH indicator from cauliflower. Crush the leaves of the cabbage. Then put it in any ware bowl and fill half the bowl with water.
Heat the bowl within 20-30 minutes. The water should be hot and get dark purple color.
Shake the bowl, pour the purple liquid in the cup, but leave the pieces of cabbage in the bowl. Indicator pH ready.
Pour the solution into several small cones and try to mix with different substances (citric acid, vinegar, soda ash solution). If the solution is sour - so the indicator will change colour from purple to pink, if alkaline - the indicator will turn green!