Urgent for some common sense and cutting-edge knowledge or information about chemistry.

Common sense (1) Why can fruit relieve alcoholism?

Excessive drinking is often a sign of drunkenness. Drunkenness is often accompanied by symptoms such as increased language, ineffective tongue, fever and numbness in cheeks, dizziness, and unstable standing ... These are all manifestations of drunkenness, and it is necessary to sober up.

Many people know that eating fruit or drinking 1-2 clean vinegar can relieve hangover. What is the truth?

This is because fruits contain organic acids, for example, apples contain malic acid, oranges contain citric acid, and grapes contain tartaric acid. The main component of wine is ethanol, and organic acids can interact with ethanol to form esters to achieve the purpose of hangover. Similarly, vinegar can relieve alcoholism because it contains 3-5% acetic acid, which can react with ethanol to produce ethyl acetate.

Although the fruit with sour taste and vinegar can alleviate the anesthetic effect of excessive ethanol, the effect is not ideal due to the interference of many factors in the above esterification reaction. Therefore, the best way to prevent drunkenness is not to drink too much.

Common sense (2) Fried dough sticks and chemistry

Fried dough sticks are one of the traditional popular foods in China. They are not only cheap, but also crispy and delicious, suitable for all ages.

Fried dough sticks have a very long history. In ancient China, fried dough sticks were called "coolers". Liu Yuxi, a poet in the Tang Dynasty, described the shape and making process of fried dough sticks in a poem about cold weapons: "When you rub jade with your hands, you will find that it is blue, oily and light yellow; It doesn't matter if you sleep in the spring at night, but the beauty of the plaque is wrapped around your arm. " How vividly this poem depicts fried dough sticks! But when you eat crispy and delicious fried dough sticks, have you thought about the chemical knowledge in the process of making fried dough sticks?

Let's take a look at the making process of fried dough sticks: first, mix the dough, that is, add fresh yeast or old noodles (fermented noodles) and flour to knead the dough to a certain extent, then add proper amount of soda ash, salt and alum to knead the dough, and then cut it into strips with a thickness of 1cm and a length of 10cm. Every two strips are stacked up and down, pressed with narrow wooden strips in the middle, and stretched after rotation.

During the fermentation process, due to the propagation and secretion of enzymes (mainly glucoamylase and alcoholase) in dough, a small part of starch is converted into glucose, and then from glucose to ethanol, producing carbon dioxide gas. At the same time, some organic acids are produced, which react with ethanol to produce aromatic esters.

The carbon dioxide gas produced by the reaction makes the dough produce many small holes and expand. The presence of organic acids will make dough sour. The purpose of adding soda ash is to neutralize excess organic acid, produce carbon dioxide gas and further expand the dough. At the same time, soda ash is dissolved in water and hydrolyzed; After frying in a hot oil pan; Due to the production of carbon dioxide, fried fritters are more loose.

From the above reaction, we may be worried. Isn't there sodium hydroxide in the fritters? How can fried dough sticks with such strong alkalinity taste delicious? However, its ingenuity is also here. When free sodium hydroxide appears in the dough, alum in the raw material immediately reacts with it, so that the free sodium hydroxide becomes aluminum hydroxide. Gel solution or dry gel of aluminum hydroxide is used as antacid in medicine, which can neutralize gastric acid and protect ulcer surface, and can be used to treat hyperacidity, gastric ulcer and duodenal ulcer. The main component of the common stomach medicine "Weishuping" is aluminum hydroxide. Therefore, some Chinese medicine prescriptions say that fried dough sticks have inhibitory effect on gastric acid and have certain curative effect on some stomach diseases.

Common sense (3) Discrimination of real gold With the continuous improvement of people's living standards, more and more people wear gold ornaments. When buying, people always want to buy pure gold, which is called pure gold.

Real gold is glittering and heavy, with a specific gravity of 19.3 (g/cm 3). It is not afraid of corrosion, and its color remains unchanged after thousands of years.

Although real gold can shine, it is not necessarily real gold, such as fool's gold and artificial imitation gold (such as titanium nitride). )

Fool's gold refers to pyrite (FeS2) or chalcopyrite (CuFeS2) that can emit golden luster. They often fool people who lack mineral knowledge with their charming beauty and get their nicknames.

Fool's gold, imitation gold and real gold are the same color, and it is difficult to distinguish between true and false. But as soon as they touched the touchstone, their "true colors" were exposed. Looks like the touchstone is mysterious. In fact, it is just a very common stone in nature, gray-black, goose-shaped, and has weathered into the shape of a goose egg. When testing, as long as the test object is scratched on the touchstone, its true colors will be revealed: the stripes drawn by pyrite are black, and the stripes drawn by chalcopyrite are dark green; And what about real gold? The scratches left on the touchstone turned golden again.

"Gold is not enough." Natural gold is still not absolutely pure, what's more, gold is rare and expensive. So many gold ornaments add some copper and silver to gold to make alloys. When people buy gold, they are faced with the problem of how to identify the uniform purity of gold and determine its color (gold content). With the "golden eye" of the touchstone, we can not only distinguish the authenticity of gold; You can also see through the pros and cons of gold (in terms of "K", 24K … 100% is the best; 18k … 75% is the second; 12K...50% is bad) This is because the colors of gold ornaments with different colors are slightly different. People extract standard gold bars with different gold contents in proportion in advance, draw color marks with known content one by one on the touchstone, then cut the gold ornaments to be tested on the same touchstone, compare the two, and finally judge the color by experienced experts. This method is simple and feasible, but there are some errors. We must find a more accurate method and choose an instrument with sharper eyes.

With the development of science and technology, laser gold detector was invented abroad. The laser beam irradiates gold, alloy or imitation gold, and turns them into vapor respectively, showing different spectral lines and their intensities, so that it can be correctly identified, and the operation is simple without worrying about the loss of gold. During inspection, the knife made by laser is smaller than the needle tip, and the sample loss is less than one billionth of a gram. It is really very small and is very popular with customers and jewelers. This instrument for uncovering all kinds of gold ornaments on Lushan Mountain is worthy of the name.