In household and industrial chemistry, synthetic detergents are mainly prepared from which type of starting material?

Introduction / Context:
This question contrasts traditional soaps with modern synthetic detergents, an important topic in applied chemistry. Soaps are typically sodium or potassium salts of higher fatty acids derived from natural fats and oils, whereas synthetic detergents are produced from petrochemical sources. Understanding that synthetic detergents come from petroleum hydrocarbons rather than directly from animal or vegetable fats helps explain their different properties, such as performance in hard water and their widespread use in cleaning products.

Given Data / Assumptions:
- The focus is on synthetic detergents used for cleaning in homes and industries.
- You are asked which starting material is used to prepare these synthetic detergents.
- Options include potassium salts of higher fatty acids, sodium salts of higher fatty acids, hydrocarbons of petroleum, and glycerides.
- It is assumed that you can distinguish between soaps and synthetic detergents based on their raw materials.

Concept / Approach:
The key concept is that soaps and synthetic detergents differ in both composition and source. Soaps are produced by saponification of fats and oils, creating sodium or potassium salts of long chain carboxylic acids. Synthetic detergents, however, are usually made from petrochemical hydrocarbons that are sulfonated or otherwise modified to create molecules with hydrophobic and hydrophilic parts. These detergent molecules are designed to work effectively in a range of water conditions, including hard water. Therefore, the correct starting material for synthetic detergents is hydrocarbons of petroleum, not the fatty acid salts or glycerides associated with traditional soap making.

Step-by-Step Solution:
Step 1: Recall that soaps are sodium or potassium salts of higher fatty acids obtained from natural fats and oils. Step 2: Remember that synthetic detergents are called synthetic because they are produced from artificially processed petrochemical feedstocks rather than directly from natural fats. Step 3: Identify hydrocarbons of petroleum as the key raw chemicals processed in the petrochemical industry to create detergent molecules. Step 4: Recognize that potassium and sodium salts of higher fatty acids and glycerides are closely related to soap formation, not to the main synthetic detergent routes. Step 5: Conclude that synthetic detergents are primarily prepared from hydrocarbons of petroleum, so that option is correct.

Verification / Alternative check:
You can verify this by reading any standard discussion of soaps and detergents in school chemistry textbooks. These chapters typically highlight that synthetic detergents, such as linear alkylbenzene sulfonates, are manufactured from petroleum based hydrocarbons. The text contrasts them with soaps derived from natural triglycerides in animal fats and vegetable oils. Industry information about surfactants also lists petrochemical hydrocarbons as starting materials. This consistent description confirms that hydrocarbons of petroleum are the correct answer.

Why Other Options Are Wrong:
Potassium salts of higher fatty acids and sodium salts of higher fatty acids are the basic chemical nature of soaps, not synthetic detergents. They are produced by reacting fats or oils with strong bases like sodium hydroxide or potassium hydroxide. Glycerides are esters of glycerol and fatty acids found in natural fats and oils and are also used in the production of soaps, not in the primary synthetic detergent routes. These substances are therefore associated with soap manufacture, not with the petrochemical synthesis of detergents.

Common Pitfalls:
Students sometimes confuse soaps and detergents and may select sodium salts of higher fatty acids because they recall that soap cleans. Others may not appreciate the difference between natural and synthetic sources. Another error is to choose glycerides due to their connection to fats without noting that the question specifically refers to synthetic detergents. To avoid these mistakes, remember that soaps are based on fatty acid salts from natural fats, while synthetic detergents are made from petroleum derived hydrocarbons processed in chemical plants.

Final Answer:
Synthetic detergents are mainly prepared from Hydrocarbons of petroleum.