-
Anonymous users2024-02-06Color reaction: The color of a chemical is changed by a change in the chemical (new substances are generated). Nitric acid reacts with proteins and can make them yellow.
This is called the color reaction of the protein, which is often used to identify some proteins and is one of the characteristic reactions of the protein. Protein color reaction 1, biuret reaction biurea NH2 CO NH2 CO NH2 is a condensation product of 2 molecules of urea, (NH2 CO NH2) after losing 1 molecule of ammonia. The polypeptide molecule contains many peptide bonds CO NH that are structurally similar to biuret.
Therefore, the addition of alkali and a small amount of copper sulfate to the protein solution results in a complex of purplish-red copper. Any protein or proteolytic intermediate product has a biuret reaction. This property shows that there is a certain relationship with the number of peptide bonds contained in the protein molecule.
The higher the number of peptide bonds, the darker the color. It can be shown to be due to the formation of a +2 valence copper complex. 2. Protein yellow reaction Some proteins are yellow when they interact with concentrated nitric acid, and they turn orange if they are treated with ammonia.
Protein molecules that have this reaction are generally present in the benzene ring. 3. Protein reacts with ninhydrin Proteins, like amino acids, can also react with ninhydrin hydrate reagent in purple color, which can identify proteins.
-
Anonymous users2024-02-05Let's put it this way: 1. There are metals, iron, and copper reactions in ionic reactions (precipitation is counted, and it is the point).
2 Heating There are copper and there are also (cu cuo) different.
3 Flame color reflection.
I don't know if you are talking about the color before and after the reaction, or the color during the reaction, such as combustion, read the textbook before and after, and say it.
-
Anonymous users2024-02-04There are many substances that are commonly colored in high school chemistry, such as:
Yellow: silver iodide, silver phosphate, yellow phosphorus.
Light yellow: sulfur, sodium peroxide, silver bromide, concentrated nitric acid mixed with nitrogen dioxide, concentrated hydrochloric acid mixed with trivalent iron ions, nitrobenzene dissolved with nitrogen dioxide.
Grayish-yellow: magnesium nitride.
Brownish-yellow: ferric chloride solution, iodine.
Black: copper sulfide, silver sulfide, cuprous sulfide, lead sulfide, ferrous sulfide, ferrous oxide, ferric oxide, manganese dioxide, copper oxide, silver oxide, carbon.
Green: copper chloride solution, basic copper carbonate.
Red: copper oxide, copper, iron thiocyanide ions.
Brown: solid hand body chloride is transported iron, solid copper chloride.
Purple: potassium permanganate solution, iodine element in carbon tetrachloride solution.
Gray: arsenic, tin, iron carbide.
Brown: iodine, iron hydroxide.
Blue: copper sulfate pentahydrate, copper hydroxide, starch meets iodine, purple litmus test solution in an alkaline environment.
-
Anonymous users2024-02-03Color: Color-related iron, copper, potassium permanganate, dichromatic acid, bromine water, color: metallic elements (elemental, compounds) burning on the flame, flame color, sodium, brass, green, violet.
-
Anonymous users2024-02-02Different states have different colors. In high school, copper, iron and some gases are more common.
-
Anonymous users2024-02-01Flame color reaction, acid and alkali change the color of the test paper, the generation and precipitation of colored ions, and the oxidation of metal substances.
-
Anonymous users2024-01-311.The protein turns yellow when it encounters nitric acid (if it is splashed on ** by a liquid during an experiment, ** turns yellow).
2.Phenols appear purple when Fe3+.
In the case of SCN - appears blood-red.
light green or gray-green) when encountering a stronger oxidant becomes Fe3+ (yellow).
white), in the air or in solution, it will quickly change to gray-green precipitate, and finally to Fe(OH)3 reddish-brown precipitate.
6.White anhydrous copper sulfate turns blue when dissolved in water.
7.The starch turns blue when exposed to iodine.
8.Oxidative bleaching: Hypochlorous acid HCO (chlorine gas passes through the moist colored cloth strips, causing the colored cloth strips to fade, which is actually chlorine gas and water generation.
Hypochlorite HCL, and hypochlorite HCO has strong oxidizing properties to fade the cloth strip), ozone O3, hydrogen peroxide H2O2, etc. can make potassium permanganate solution fade.
9.Sulfur dioxide is passed into the magenta solution, the magenta solution fades, but non-oxidative bleaching, reheat the magenta solution, and the color is restored.
10.Unsaturated hydrocarbons (such as olefins, alkynes, etc.) can discolor bromine water or potassium permanganate solutions (addition reaction with bromine to reduce potassium permanganate).
11.Phenol (solid) is exposed in the air and oxidized by oxygen to turn pink.
Colorless) O2 = 2NO2 (reddish-brown).
Reddish-brown) = N2O4 (colorless).
Due to the limited technology, the equal sign here should be the reversible sign (the positive reaction condition seems to be pressurized, and the reverse reaction condition is reversed).
14.Black copper oxide CuO reacts with reducing substances (such as hydrogen H2, carbon monoxide CO, carbon C, etc.) to form red copper Cu.
15.The aldehyde group reacts with the silver ammonia solution to form a bright silver mirror.
The reaction is to be carried out in a water bath).
16.The aldehyde group reacts with the new copper hydroxide suspension, and the reaction phenomenon is blue flocculent precipitation (Cu(OH)2) to brick red precipitation (Cu2O).
17.Inorganic reactions (precipitation or colored ions).
ch3coo with.
PB2 BA2 and SO42
BA2 and SO32
SN2 vs. SO42
Ag vs. Cl
hg＋(hg2cl2)
With Cl and so on are to generate a white precipitate.
With the base to generate Cu(OH)2 blue precipitate.
Fe(OH)2 is formed with alkali, but it is easily oxidized, so there is no white precipitate as we expect in the experimental phenomenon, but gray-green precipitate, and finally Fe(OH)3 reddish-brown precipitate is formed after a period of time.
With alkali to form Fe(OH)3 reddish-brown flocculent precipitate.
-
Anonymous users2024-01-30Purple reaction in Fe3+:
Phenols meet SCN- and appear blood-red: Fe3
Fe2 (light green. Gray-green) turns into Fe3+ (yellow) Fe(OH)2 (white) when the oxidant is encountered, quickly turns gray-green in the air (in solution), and finally turns Fe(OH)3 reddish-brown.
Soluble in water turns blue: white anhydrous copper sulfate powder.
Iodine turns blue: starch oxidation bleaching: hypochlorous acid (chlorine gas passes through moist colored cloth strips) ozone hydrogen peroxide ....
Sulfur dioxide passes into magenta.
Bromine potassium permanganate fading: unsaturated hydrocarbons (with bromine addition. Reduced potassium permanganate) phenol is exposed in the air and oxidized by oxygen to turn pink.
2NO (colorless) O2====2NO2 (red-brown) NO2 (red-brown) ====N2O4 (colorless).
Heating) Cuo (black) CO (or H2) ====Cu (red) CO2 (or H2O).
The aldehyde group reacts with a silver ammonia solution: colorless to shiny silver mirror.
Aldehyde group reacts with the new copper hydroxide suspension: blue precipitate to brick red precipitate inorganic reaction (precipitate or colored ions).
ch3coo with.
PB2 BA2 vs. SO42 SO32
SN2 vs. SO42
AG or HG (HG2Cl2).
With cl and so on are raised to white precipitates.
Cu2 precipitates with alkaline blue. Fe2 precipitates with alkaline white. Fe3 with alkali reddish-brown flocculent sweat. It's just too much.
In this reaction, there is only the electron gain and loss of nitrogen element, the valency has risen and decreased, so C is wrong, the increase of nitrogen in metadimethylhydrazine is oxidized, it is a reducing agent, so a is wrong, the reaction is the recombination of atoms, so there is an endothermic and exothermic process, C is wrong, D is left, of course, there are eight electrons transferred from two N2O4 to N2 D is correct.
Organic substitution can also be understood as replacement.
The equation in your book must be like this: 2h2(g) +o2(g) = 2h2o(l), right? >>>More
It doesn't seem to be a contradiction. The structure of the electron layer is the same, which means that it is the same three-layer and the same four-layer ......For example, Na and Cl, the radius of Cl is much smaller. >>>More
There are two main factors that affect the radius: one is the number of electrons outside the nucleus (generally speaking, the more electrons there are, the farther away from the nucleus, the larger the radius). >>>More