The shelf life of laboratory chemicals varies widely, with some lasting for years and others having very short lifespans

 The shelf life of laboratory chemicals varies widely, with some lasting for years and others having very short lifespans. Factors like the chemical's properties, storage conditions, and whether it's been opened all play a role. Some chemicals, like those that form peroxides (e.g., diethyl ether, tetrahydrofuran), require special handling and disposal due to the potential for dangerous reactions. 

Here's a general overview:

General Shelf Life Guidelines:

Acids and Bases:

Many acids and bases, like hydrochloric acid, sulfuric acid, and sodium hydroxide, have a shelf life of 1-2 years if stored properly, though some may last indefinitely. 

Solvents:

Solvents like ethanol and chloroform typically have a shelf life of 2 years. 

Peroxide-forming chemicals:

These require special attention. Diethyl ether and tetrahydrofuran, for example, should be discarded or disposed of within a year of opening, and potentially sooner if peroxides are suspected. 

Powders:

Many dry chemicals, like sodium chloride, are stable for long periods if stored dry and sealed. 

Solutions:

Solutions tend to have shorter shelf lives than their solid counterparts, especially if they are aqueous. 

Factors Affecting Shelf Life:

Storage Conditions: Light, temperature, and humidity can all affect a chemical's stability. 

Opened Containers: Once a container is opened, the shelf life is often reduced. 

Reactions with Air or Moisture: Some chemicals react with oxygen or water, leading to degradation. 

Peroxide Formation: Some chemicals can form explosive peroxides over time, especially upon evaporation or exposure to light. 

Important Considerations:

Manufacturer's Recommendations:

Always refer to the manufacturer's recommendations for specific chemicals, found on the product label, safety data sheet (SDS), or technical data sheet. 

Date Received and Opened:

Date all chemicals when received and again when opened to track their age. 

Visual Inspection:

Regularly inspect chemicals for signs of degradation, such as discoloration, crystal formation, or changes in consistency. 

Proper Disposal:

Dispose of chemicals according to your institution's procedures, especially those that have exceeded their shelf life or show signs of degradation. 

Specific Examples:

Acetic acid: 2 years.

Hydrochloric acid: 1-2 years (manufacturer's guarantee), but can last indefinitely if stored properly.

Hydrogen peroxide: 2-3 years, but should be checked for stability by oxidizing potassium iodide.

Sodium hydroxide: 2 years.

Ethanol: 2 years.

Diethyl ether: 2 years, but should be discarded or disposed of within a year of opening.

Tetrahydrofuran: 2 years, but should be discarded or disposed of within a year of opening.

Potassium dichromate: 2 years.