Free Master of Chemistry: Industrial Chemistry Questions and Answers

Question 1

Which way of operation is not appropriate for a chemical or biochemical plant?

Accepted Answer

Discontinuous

Answer

Chemical and biochemical plants typically operate in well-defined modes such as batch-wise, semi-continuous, or continuous, each suited for different production scales and product types. While batch-wise operation is a type of discontinuous process, the term 'discontinuous' on its own might imply an unstructured or inefficient stop-and-start operation that lacks the controlled nature of a batch process. Such an unorganized 'discontinuous' operation would generally not be appropriate for efficient plant functioning.

Question 2

When is a separation step in a manufacturing process not necessary?

Accepted Answer

When there is a complete conversion

Answer

A separation step in a manufacturing process is typically necessary to isolate the desired product from unreacted starting materials, catalysts, and byproducts. However, if a reaction achieves complete conversion of reactants to the desired product with no significant byproducts, then the product stream would be essentially pure, and a dedicated separation step might not be required. This ideal scenario eliminates the need for purification.

Question 3

Why is there a need for separation if just 5% of ethylene is transformed to ethylene glycol?

Accepted Answer

To recover the unreacted Ethylene Glycol

Answer

If only 5% of ethylene is transformed into ethylene glycol, it means 95% of the initial ethylene remains unreacted. For the process to be economically viable and environmentally responsible, this large quantity of unreacted ethylene must be separated from the product (ethylene glycol) and subsequently recovered. The recovered unreacted ethylene can then be recycled back into the reactor, significantly improving the overall process efficiency and reducing raw material costs.

Question 4

Will the aforementioned reaction call for a separation procedure?

Accepted Answer

No

Answer

Based on the premise from the previous question (Q24), where only 5% of ethylene is converted to ethylene glycol, a separation procedure is indeed necessary. The unreacted 95% of ethylene must be separated from the 5% product (ethylene glycol) for product purification and reactant recycling. Therefore, the statement that a separation procedure is not called for is inconsistent with standard chemical engineering principles for low-conversion reactions.

Question 5

How is the diethyl ether removed from ethylene during the production of ethanol?

Accepted Answer

Light-ends tower

Answer

In industrial ethanol production, especially via the hydration of ethylene, diethyl ether is a common byproduct. A light-ends tower, which is a type of distillation column, is specifically used to separate more volatile components like diethyl ether from the desired ethanol product. This separation leverages differences in boiling points to ensure the purity of the final ethanol stream.

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Practice Test

Free Master of Chemistry: Industrial Chemistry Questions and Answers