Q:Pls help me define a catalyst.?

catalyst is a substance which increases or decreases the rate of recation without being involve in the reaction

Q:in acid-catalyzed reaction,there are some books show the acid catalyst as H+ and there are some show it as H3O+ .Are they the same?

Sort of. If the reaction is under aqueous conditions (any water is included in the reaction), then yes, H+ = H3O+. This is because free protons present (H+) will be coordinated generally to molecules of water [thus H2O + H+ =H3O+ ]. But there are reaction conditions where water is not present, but an acid catalyst is still possible. In these cases, the acid catalyst may frequently be indicated as simply H+. Either way, the function in most of your reaction mechanisms is basically the same, whether indicated as H+ or H3O+ -- and that's to protonate molecules (Lewis or Bronsted bases) with H+. Concentrated sulfuric acid would be an example of a mostly-anhydrous (no water) strong proton/acid source (H+). Hydrochloric acid (HCl) frequently is available as an aqueous solution, even concentrated HCl is an aqueous solution of HCl. HCl itself is a gas under ambient conditions... but it has solubility in water and thus is conveniently sold frequently as an aqueous solution (which could be represented as H3O+)

Q:What is the chemical vinyl chloride and benzene plus catalyst?

Looks like no ethyl benzene, it is vinyl benzene

Q:Can manganese dioxide do any catalyst for chemical reactions?

The catalyst is involved in the reaction during the reaction and is reduced to the original composition after the reaction is completed. For example: heating decomposition of potassium permanganate when adding potassium permanganate. Potassium permanganate decomposition process, potassium permanganate is involved in the reaction, the specific way is not clear. And finally appeared with potassium permanganate. Reaction before and after the catalyst morphology changes, particles become powder, powder particles and so on.

Q:what is a catalyst?

A catalyst helps make a reaction go forward faster or slower but a catalyst is not consumed by the reaction itself. The catalyst may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive catalysts. Catalysts that slow down the reaction are called negative catalysts or inhibitors. Substances that increase the activity of catalysts are called promoters and substances that deactivate catalysts are called catalytic poisons. For instance, in the reduction of ethyne to ethene, the catalyst is palladium (Pd) partly poisoned with lead(II) acetate (Pb(CH3COO)2). Without the deactivation of the catalyst, the ethene produced will be further reduced to ethane

Q:The future direction of employment how, in what kind of units to do what work, how the closure rate? The

Generally in the chemical plant to do engineering design engineers, the past few years, science and engineering graduates generally do not worry about work.

Q:Is the chemical reaction rate constant related to the amount of catalyst used?

The decomposition of hydrogen peroxide, manganese dioxide in addition to the catalyst, but also in which it can be considered a carrier (from the surface of manganese dioxide to emit small bubbles, you should be able to see), so the amount of more than certainly can speed up the reaction.

Q:What are the methods of catalyst characterization?

Chemical means, according to the different detection methods, methods are different, but is to explain the chemical properties, chemical structure characteristics.

Q:Chemistry teaching and learning a bit difficult, thank you

2NO + 2CO = 2CO2 + N2