The concentration of concentrated sulfuric acid is of course higher, resulting in strong oxidation, dehydration and water absorption that dilute sulfuric acid does not have.
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For example, if you put a drop of concentrated sulfuric acid on the toilet paper, the toilet paper will turn black (dehydration carbonization); If a bottle of concentrated sulfuric acid is placed in the air, its weight will gradually increase and the concentration will become smaller (water absorption); Concentrated sulfuric acid can REDOX with copper, does not produce hydrogen, but produces sulfur dioxide, and contact with iron will passivate iron, which is the reason why concentrated sulfuric acid can be transported in metal tanks (strong oxidation).
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Dilute sulfuric acid is strongly acidic and can react with active metals to form hydrogen and corresponding sulfates. But dilute sulfuric acid does not have the ability to absorb water and dehydrate.
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From a physical point of view, concentrated sulfuric acid is dense, viscous, and looks like a transparent viscous liquid (actually, when I look at it, I think it is not so viscous); Dilute sulfuric acid is less dense, less viscous, and closer to water.
Sulfuric acid is sulfur trioxide dissolved in water, so when heating, sulfuric acid will decompose, decomposition of sulfur dioxide is very normal, many times in the absence of nitric acid, heating concentrated sulfuric acid can dissolve a lot of metal and metal sulfide, while producing a large number of harsh sulfur dioxide. This is the oxidation of concentrated sulfuric acid
If there is no catalyst, it takes more than 900-1000 degrees to decompose a large amount of sulfur dioxide. In fact, concentrated sulfuric acid first breaks down into sulfur trioxide. Concentrated sulfuric acid is a mass fraction greater than or equal to 70% of sulfuric acid aqueous solution, commonly known as bad water. Concentrated sulfuric acid is highly corrosive: at atmospheric pressure, boiling concentrated sulfuric acid can corrode all metals except iridium and ruthenium, which can corrode the number of metal elements even exceeds aqua regia.
Sulfuric acid has strong oxidation at high concentrations, which is one of the biggest differences between it and dilute sulfuric acid. At the same time, it also has dewater, volatile, acid, water absorption and so on. Similar to nitric acid, the reduction product may be sulfur dioxide, elemental sulfur, or sulfide, depending on the type and amount of reducing agent.
Concentrated sulfuric acid is relatively difficult to decompose at room temperature, and it needs to be heated to more than 900 degrees Celsius to decompose and release sulfur dioxide. However, in the case of adding some heavy metals as catalysts, the reaction will produce sulfur dioxide. The chemical equation for the reaction of zinc and concentrated sulfuric acid is: Zn 2H? SO? (concentrated)=ZnSO? SO? ↑ 2H? O.
At the beginning of the reaction, concentrated sulfuric acid shows strong oxidation, and the reduction product is SO? ; As the reaction proceeds, sulfuric acid is continuously consumed and water is continuously generated, resulting in concentrated sulfuric acid to dilute sulfuric acid, which will undergo a replacement reaction with zinc and generate hydrogen.
Concentrated sulfuric acid is oxidizing, ethylene is reducing, during the reaction, the ethylene π bond breaks, breaking an electron, reducing the S atom, forming sulfur dioxide.
Concentrated sulfuric acid has dehydration, ethanol dehydration to produce carbon, carbon and concentrated sulfuric acid reaction will produce sulfur dioxide and carbon dioxide. If there is no catalyst, it takes more than 900-1000 degrees to decompose a large amount of sulfur dioxide.