What is the safest assumption to make when working with unknown chemical substances?

When working with unknown chemical substances, the safest assumption is to treat them as hazardous and to wear appropriate personal protective equipment (PPE). This is vital because unknown substances can contain toxic, corrosive, or reactive materials that can pose serious health risks. By assuming that they are hazardous, you take the necessary precautions to protect yourself and others in the lab.

Wearing appropriate PPE, such as gloves, goggles, and lab coats, minimizes the risk of exposure to potentially harmful chemicals, which may not show immediate effects. It is crucial to prioritize safety and be prepared for any potential risks tied to these substances, since the chemical's properties are unknown until properly analyzed.

Assuming that unknown chemicals are harmless or safe is dangerous and can lead to accidents. Such oversights might result in severe health issues, chemical burns, or reactions that could endanger lab personnel and compromise the laboratory environment. Therefore, the practice of wearing PPE as a fundamental safety measure is essential in any laboratory where unknown chemicals are handled.