Catalysts
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catalyst
substance that: • speeds up rate of reaction • does not alter the products • chemically and in mass unchanged
Describe 3 common catalysts
iron: -catalyses process of making ammonia (Haber process) vanadium oxide: -stage in making sulfuric acid (contact process) manganese dioxide: -decomposition of hydrogen peroxide (produces water and oxygen)
What type of substance are catalysts normally made from?
transition metals or compounds of transition metals
reaction pathway
The sequence of reactions needed to produce a desired product from a particular set of raw materials.
how do catalysts work
they provide an alternative reaction pathway with a lower activation energy does not change frequency of collisions increases frequency of successful collisions due to a greater proportion of collisions meeting the lower activation energy
reaction profile
Chart showing how the energy of reactants and products changes during a reaction
how is the effect of a catalyst on the activation energy shown
chart called a reaction profile shows the energy of reactants and products with and without a catalyst
enzymes and catalysts
an enzyme is a biological catalyst rather than chemical control reactions in cells and industry - reactions can happen at a lower temperature and pressure
give an example of a type of biological catalyst
yeast (a fungus) contains enzymes used to produce alcoholic drinks by fermentation of sugars
Describe three features of a catalyst Explain how a catalyst works
• substances that speed up rate of reaction • without altering the products • unchanged chemically and in mass at the end of the reaction catalysts provide an alternative reaction pathway with a lower activation energy
Describe how a student could show that the mass of a catalyst is unchanged during a reaction
measure and record the mass at the start filter out the catalyst at the end, dry it off, and measure it again