Chemistry is a unique and interesting science, with which you can explain many of the processes that occur around us in life. For example, why the iron gradually rusts, and also why the aluminum spoon heats up so quickly if it is lowered into hot tea. Chemistry surrounds us absolutely everywhere: acetic acid or vinegar, sodium chloride or common salt known to everyone, as well as substances such as iodine, bleach, alcohol and many others. But in chemistry there is such a substance that everyone knows, and it is called starch. Starch can also be obtained by the chemical method, but most often it is extracted from potatoes. Let's take a closer look at everything connected with it, starting with the chemical formula and ending with its properties and how starch can be recognized.
Starch, the formula of which is as follows: 6105, has a number of interesting properties. For example, everyone's favorite jelly freezes only for the reason that it contains a fairly large amount of starch. Starch looks like an ordinary powder, has no smell, is practically devoid of taste, and the most interesting thing is that it creaks if you rub it a little. This physical property of starch is due to the fact that the starch molecules are quite large.
In general, starch, its formula and some properties were discovered relatively recently. Starch is produced by plants, and not only potatoes, but also others, such as, for example, corn and wheat. Potato starch contains only twenty percent, while in wheat and corn grains its amount exceeds the mark of seventy percent. Starch is formed when, during photosynthesis, six molecules of carbon dioxide and five water molecules are combined, after which one starch molecule and six oxygen molecules are formed.
As indicated above, the chemical formula of starch contains six carbon atoms, ten hydrogen atoms and five oxygen atoms. This indicates not only that the starch molecule is very large, but also that it has an absolutely organic origin, that is, it belongs to a section of chemistry called organics. This substance is considered complex, belongs to the section of polysaccharides, although it is not a sugar or similar substance. Also, starch is referred to as organic substances containing oxygen, or otherwise - oxygen-containing organic substances.
The structural formula of starch is also considered complex, its structure can be viewed on the Internet, since it is simply impossible to transfer it by letter. We can only say that starch, its formula more precisely, contains several OH groups, each of which is connected to a carbon atom. Many people confuse this molecule with a molecule of some alcohol when they hear about the OH group, but in fact starch is hidden in the C6H10O5 molecule.
If you want to recognize starch, then you do not need to think about it for a long time. A qualitative reaction for the presence of starch in a substance is as follows: a few drops of iodine solution are simply dripped into a test tube. If the solution immediately begins to be removed, then you can no doubt sign the test tube and be sure that it contains starch. If you want to test this reaction in good conditions, take a small potato, cut it, and then gently pipette a few drops of iodine (what is sold in pharmacies for cauterizing wounds). After some time, you will see an obvious effect of a qualitative reaction on starch: potatoes in the place where iodine got in will gradually begin to turn blue.
So, now you know a lot about starch (what is starch, formula, properties and qualitative reaction). Of course, all the above information is not complete, but if you are preparing for the standings in organic chemistry, it will certainly help you.