Why should a chemical not be used past its expiration date?

• A. Expired chemicals are guaranteed to produce more accurate experimental results.
• B. The color of the chemical will always change after the expiration date.
• C. Its chemical properties may have changed, leading to reduced effectiveness or increased hazards.
• D. Expired chemicals always become completely inert and harmless.

Answer: (C)

Verified step by step guidance

1. Understand that the expiration date on a chemical indicates the time period during which the manufacturer guarantees the chemical's purity, stability, and effectiveness.
2. Recognize that after the expiration date, the chemical may undergo decomposition or other chemical changes, which can alter its properties.
3. Consider that these changes can lead to reduced effectiveness in reactions or experiments, meaning the chemical may not behave as expected.
4. Acknowledge that some expired chemicals can become hazardous due to the formation of harmful byproducts or increased reactivity.
5. Therefore, using chemicals past their expiration date can compromise experimental accuracy and safety, which is why it is generally advised against.