Chemical Industry 6: Manufacturing

Question 1

What 2 principal need to be considered to determine the most economical operating conditions

Answer 1

1. Equilibrium

2. Rate

Question 2

In terms of pressure and temperature suggest conditions which favour yield, rate & be economical ( forward reaction exo thermic)

What would you want ideally ( economical makes it slightly different to usual)

Answer 2

Normally would decease temp = increase yield
but decrease yield decreaese rate

So need to COMPROMISE with the temperature and increase it to increase efficiency ( i.e be more economical)

Similar for pressure ideally want to increase both pressure and temperature

Question 3

Define raw materials

Answer 3

Starting point of any chemical process

Question 4

What do raw materials make

Answer 4

Feedstocks

Question 5

Define feedstocks

Answer 5

Reactants that go into chemical equation

Question 6

Describe how feedstocks created from natural gas

Answer 6

Natural gas = raw material –> ( fractional distillation) –> methane, ethane, propane, butane –> ( steam cracking) –> ethene, propene

Question 7

Describe the batch process ( 3) and give example

Answer 7

1. Starting materials into vessel + react together
2. Reaction complete= product separated from reaction mixture
3. Process repeated until required amount of product made

Eg. Cooking pasta 1. = water + plaster into pot

2. = draining water from pasta
3. Cleaning pot and re measuring another set of ingredients

Question 8

Describe the continuous process ( 2) and give example

Answer 8

1. Starting materials fed in at one end + react together
2. Product removed from other end in continuous flow

Eg. Conveyer belt ( never stops)
Making electricity, production line of a car

Question 9

Define co-product

Answer 9

Produced in the same reaction as main product + often carries equal importance as main product

( In industry if a demand for Co-product fell could lead to whole reaction being uncompetitive

Question 10

Define by-product

Answer 10

Produced in a side reaction ( reaction other than desired reaction) + often regarded as waste

Question 11

In industry how do chemist’s and chemical engineers try to reduce by-products

Answer 11

By reducing the amount of side reactions occurring

Question 12

Equation for %yeild

Answer 12

%yeild = (actual/ theoretical) x100

Question 13

Define atom economy

Answer 13

Mass of product wanted as a % of all the products made

Question 14

Equation for atom economy

Answer 14

Atom economy = ( molecular mass, Mr or Ar of desired products / sum of molecular mass of all products) ×100 %

Question 15

What are the properties of raw materials

Answer 15

Scarcs & Expensive = must be carefully conserved

Question 16

What 4 things do chemical processes need to minimise

Answer 16

1. Waste
2. Cost
3. Energy use
4. Pollution

Question 17

How can chemical engineers maximise %yield

Answer 17

• by using the most efficient reaction conditions and apparatus
• to reduce energy use, cost, & conserve raw materials

Question 18

How can chemical engineers maximise atom economy

Answer 18

• by choosing the most efficient reaction to make the product
• to reduce waste & pollution

Question 19

How can energy in industry be saved in terms of heat

Answer 19

Heat energy from exothermic reactions can be used or saved to heat endothermic reactions

Question 20

Define of hazard

Answer 20

POTENTIAL that a hazardous substance has to cause harm

Question 21

Define risk

Answer 21

LIKELIHOOD the hazardous substance will cause harm