FC22: % Yield & Atom Economy

Question 1

What is the formula for calculating percentage yield

Answer 1

actual moles of product made
/
theoretical maximum number of moles of product
x 100

Question 2

State 5 reasons why we don’t always get 100% yield

Answer 2

1- side reactions - produce byproducts
2- if reaction is reversible - all reactants might not convert products
3- if there is a limiting factor as one of the reactants
4- products may be lost through purification steps (filtering, transferring between containers etc)
5- if reaction is very slow, it may not have completed

Question 3

what is the formula for calculating atom economy

Answer 3

Mr of desired product
/
sum of Mr of all products (or reactants)

x 100

Question 4

Why are reactions with high atom economy chosen in industry

Answer 4

reduces amount of limited resources needed, reduces proportion of waste that may or may not be hazardous which would require additional cost to remove or store

Question 5

what are other factors you need to consider other than atom economy when choosing what reactions to use in industry

Answer 5

percentage yield, environmental factors (pollution), fixed and variable costs for each process