17C.1 Flashcards
What is a heterogeneous catalyst
a catalyst that is in a different phase from the reactants
why are transition heterogenous solid metal catalysts usually used as a fine powder
since the catalyst action takes place on the surface so with a divided form we get an increase in surface area
why do scientists usually use heterogeneous catalysts over the homogenous catalyst
because it’s easier to separate the reaction product from the catalyst if they are in different phases
what are examples of transition metal heterogeneous catalysts
- Manganese(IV) oxide - the decomposition of hydrogen peroxide solution to form oxygen
- Vadanuim (V) oxide - Contact process
what is the reaction that takes place in the contact process (to convert Sulfur dioxide to sulfur trioxide
2SO2 + O2 ⇌ 2SO3
what is the surface aDsorption theory steps
1, Adsorption: in which one or more reactants become attached to the surface of the catalyst
- reaction: reaction occurs following the weakening of the bonds in the absorbed reactants
- Desorption: in which teh reaction products become detached from the surface of the catalyst
what is aDsorption
the process that forms when reactant form weak bonds with a solid catalyst
what is desorption
the process that occurs when the products leave the surface of the catalyst
how is Vanadium (V) Oxide used in teh contact process
step 1: the sulfur dioxide is adsorped into the vanadium (V) oxide and a redx reaction occurs (V2O5 + SO2 –> V2O4 + SO3) in this reaction the oxidation number of Vanadium drops from 5+ to 4+ and the sulfur trioxide is desorbed from the Vanadium (V) oxide surface
step 2: oxygen reacts with the V2O4 intermediate on the surface of the catalyst and another redox reaction occurs (V2O4 + 0.5O2 —> V2O5) that increases the oxidation number of Vanadium from 4+ to 5+ and regenerates the original catalyst
what is teh current problem caused by cars
many cars have contributed to increase the amount of pollution from exhaust gas
what are the two most dangerous gases that are formed by cars and how are they formed
-Carbon monoxide is formed from incomplete combustion, and not only does it interfere with oxygen transport in the blood flow but it also contributes towards global warming
-Nitrogen monoxide forms from reactions of nitrogen and oxygen under high temp within the engine, it can be easily oxidized to form nitrogen dioxide which contributes to global warming and also it can act as a respiratory irritant, and contribute to the formation of acid rain
what is the solution to the pollution caused by cars
catalytic convertes
what transition metal are catalytic converters made from
Platinium, rhodium, and palladium
how does the catalytic converter get rid of carbon monoxide and nitrogen monoxide
the action that the catalytic converter follows is that of the surface adsorption theory where the carbon monoxide and the nitrogen monoxide are adsorbed into the surface of the catalyst then their bonds are weakened and they react with each other to form carbon dioxide and nitrogen gas and those products are then desorbed from the surface of the catalyst (2CO + 2NO —-> 2CO2 +N2)
What is teh diff between absorption and adsorption
absorption - substance is being distributed throughout another
adsorption - only happens on the surface of the substance
