Glucose can be prepared in the laboratory by a chemical process known as hydrolysis. This process uses sucrose, commonly known as table sugar, as the starting material. Here's a breakdown of how it's done:
Laboratory Preparation of Glucose
The preparation of glucose involves a reaction with sucrose using dilute acids and alcohol.
Materials Needed:
- Sucrose (Cane Sugar)
- Dilute Hydrochloric Acid (HCl) or Dilute Sulphuric Acid (H2SO4)
- Alcohol
Procedure:
- Hydrolysis of Sucrose: Sucrose is mixed with either dilute hydrochloric acid or dilute sulfuric acid.
- Boiling: The mixture is then boiled for approximately two hours. This boiling process, in the presence of the acid, breaks down the sucrose molecule through a process called hydrolysis.
- Hydrolysis is the chemical reaction in which a molecule is broken down by the addition of water.
- In this case, the sucrose (C12H22O11) is broken down into one molecule of glucose (C6H12O6) and one molecule of fructose (C6H12O6).
- Reaction: C12H22O11 + H2O → C6H12O6 (glucose) + C6H12O6 (fructose)
- Separation: Once the hydrolysis is complete, the mixture contains both glucose and fructose. To separate the glucose from the fructose, alcohol is added to the solution while it is being cooled. This process allows for a better separation of the two sugars.
Key Points:
- Hydrolysis: The core chemical reaction, which breaks down complex sugars into simple sugars.
- Acid Catalyst: The dilute acid acts as a catalyst, speeding up the hydrolysis process.
- Separation Technique: The addition of alcohol is crucial for separating glucose from fructose, based on differences in solubility.
- Time: The reaction typically requires about two hours of boiling to complete.
Simplified Explanation
| Step | Description | Purpose |
|---|---|---|
| 1 | Mix sucrose with dilute acid. | Start the hydrolysis. |
| 2 | Boil for two hours. | Complete the hydrolysis, breaking down sucrose to glucose and fructose. |
| 3 | Cool the mixture and add alcohol. | To separate glucose from fructose. |
This process demonstrates how glucose, a vital sugar, can be extracted in the lab using a common sugar like sucrose with acids, heat and alcohol.
