YIELD AND ATOM ECONOMY

Question 1

Why may the mass of a reaction product may be less than the maximum possible?

Answer 1

• The reaction is reversible & so may not be complete
• There are side-reactions that lead to other products that are not wanted
• The product may need to be purified, which may result in loss of product.

Question 2

What is theoretical yield?

Answer 2

The maximum possible mass of a product, assuming complete reaction and no losses.

Question 3

How do you calculate the percentage yield?

Answer 3

actual yield/theoretical yield x 100

Question 4

What is the actual yield?

Answer 4

The actual mass obtained.

Question 5

How do you calculate theoretical yield?

Answer 5

Step 1: Calculate the amount of starting material
Step 2: Use the reaction ratio to calculate the amount of desired product.
Step 3: Calculate mass of desired product

Question 6

1kg = …g

Answer 6

1 x 10³

Question 7

What is the 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 other factors affect the suitability of an industrial process?

Answer 8

• Scarcity of non-renewable raw materials
• The cost of raw materials
• The quantity of energy needed.

Question 9

What is the expression used to calculate atom economy?

Answer 9

molar mass of the desired product/sum of the molar masses of all products x 100

Question 10

Addition reactions have…

Answer 10

100% atom economy.

Question 11

Elimination and substitution reactions have…

Answer 11

lower atom economies.