Atom Economy

Question 1

what three other factors are taken into consideration by industries when calculating the sustainability of a reaction

Answer 1

• the scarcity of non-renewable raw materials
• the cost of raw materials
• the quantity of energy needed

Question 2

how many different processes are there to making phosphric acid

Answer 2

two

Question 3

what is the equation for the first process

Answer 3

• Ca3(PO4)2 + 3H2SO4 = 2H3PO4 + 3CaSO4

- calcium phosphate + sulfuric acid = phosphoric acid + calcium sulfate

Question 4

what is the equation for the second process

Answer 4

• P4 +5O2 + 6H20 = 4H3PO4

- phosporus + oxygen + water = phosphoric acid

Question 5

what is the main difference between the two processes in terms of atoms economy

Answer 5

• all of the atoms in process 2 end up composing the desired product
• whereas in process 1 only a fraction of all the atoms end up the desired product
• as the rest make the unwanted product (calcium sulfate)

Question 6

what is the definition of atom economy put simpy

Answer 6

the measure of the proportion of atoms from the reactants that end up in the desired product

Question 7

what is the actual definition of atom economy

Answer 7

• the molar mass of the desired product
• divided by the sum of the molar masses of all the products
• expressed as a percentage

Question 8

what is the equation for atom economy

Answer 8

atom economy = (molar mass of desired product) / (molar mass of all the products) x 100

Question 9

what would the atom economy of process 2 be

Answer 9

100%

Question 10

the equation for process 1 was Ca3(PO4)2 + 3H2SO4 = 2H3PO4 + 3CaSO4. what would its atom economy be if the molar mass of 3CaSO4 was 408

Answer 10

• Mr of 2H3PO4 = 196
• 196 + 408 = 604
• (196 / 604) x 100 = 32.4%

Question 11

if the percentage yield was 100%, for process 2 and 80% for process 1, what would their atom economies be

Answer 11

• for process 1 it would still be 100%

- for process 2 it would still be 32.4%

Question 12

why doesnt the atom economy change despite the yield changing

Answer 12

• the yield is calculated using the theoretical yield
• which already takes the fact that all atoms arent going to compose the desired product into account
• (assuming there is another product)
• however, the atom economy is calculating the percentage of atoms of products make the desired product, and this is fixed
• so no matter how close the actual yield is to the theoretical yield, the atom economy will always remain the same

Question 13

what is the usual atom economy of an addition reaction and why

Answer 13

• 100%
• because you should only come out with one product
• with it being an ADDITION reaction n all

Question 14

what is the atom economy of an elimination or substitution reaction going to generally be

Answer 14

low

Question 15

what is the atom economy of multistep reactions going to generally be

Answer 15

low