Science - Chemistry - Quantitative Chemistry - Atom Economy And Yield - C3c Flashcards
what is the atom economy of a reaction ?
the atom economy of a reaction tells you what percentage of the mass of the reactants ends up as useful products when manufacturing a chemical
what does 100 % atom economy mean ?
all the atoms in the reactants have been turned into useful products
how do you calculate atom economy ?
relative formula mass of desired products / relative formula mass of all reactants X100
how do you calculate the percentage of ‘wasted’ product in atom economy ?
subtract the atom economy from 100
what is ‘wasted’ product ?
anything that isn’t in a desired product during a reaction
what is the atom economy of reactions that only have one product ?
100 %
why is the atom economy of reactions with one product always 100 % ?
all the reactants end up in the useful product
what are the economic advantages of having a high atom economy ?
- reactions with low atom economies are less profitable
- produces less waste
- more of the materials going into the reaction are being used well
what are the environmental advantages of having a high atom economy ?
- fewer raw materials are used
- produce less waste
- more sustainable
what is a theoretical yield ?
the amount you would get if all the reactants formed the desired products, and none of the products are lost
what is a yield ?
the amount of product you actually get in the product
what is the percentage yield ?
a comparison between the theoretical yield and the yield you actually get
what does a 100 % percentage yield mean ?
you got all the product you expected to get
what does a 0 % percentage yield mean ?
no reactants were converted into product, no product at all was made
how do you calculate the percentage yield ?
mass of product actually made (g) / maximum theoretical mass of product (g) X100
why are percentage yields never 100% ?
because some product or reactant always gets lost along the way
what are the 3 main problems when losing product in an experiment ?
- the reaction is reversible
- product is lost when it’s separated from the reactants
- unexpected reactants may be happening
how can the reaction be reversed ?
if a reaction is reversible, reactants will never be fully converted to products as the reaction goes both ways as some of the products are always reacting together to change back to the original reactants
what is a reversible reaction ?
where the products of the reaction can themselves react to produce the original reactants
what are the factors you need to consider when choosing which reaction use to make a substance on an industrial scale ?
- atom economy
- yield
- rate of reaction
- equilibrium position
- usefulness of by - products
what is the equilibrium position ?
the point at which the rates of the forward and backward reactions in a reversible reaction are the same, so the amounts of reactants and products in the reaction container don’t change
