Before mixing two chemicals in a laboratory, which of the following is the most important safety step to take?

• A. Read the safety data sheets (SDS) for both chemicals.
• B. Estimate the final color of the mixture.
• C. Check the expiration date of your lab notebook.
• D. Ensure the chemicals are at room temperature.

Answer: (A)

Verified step by step guidance

1. Understand that safety in the laboratory is paramount before handling or mixing chemicals.
2. Recognize that the Safety Data Sheets (SDS) provide critical information about the properties, hazards, handling, and emergency measures related to each chemical.
3. Identify that reading the SDS for both chemicals helps you anticipate any dangerous reactions, toxicity, or necessary protective equipment.
4. Note that other options like estimating the final color, checking the lab notebook expiration, or ensuring room temperature are less critical for immediate safety.
5. Conclude that the most important safety step before mixing chemicals is to read the Safety Data Sheets (SDS) for both chemicals.