What must be done before using a round-bottom flask in a laboratory setting?

Before using a round-bottom flask in a laboratory setting, it is essential to set a proper support in place. Round-bottom flasks are designed to provide even heating and are commonly used in processes like distillation and synthesis. However, they need to be supported adequately because their curved shape makes them vulnerable to tipping over and breaking if not securely held.

A round-bottom flask is typically precarious when filled with liquid, and without proper support such as a ring stand or clamps, it can easily fall and cause both personal injury and material loss. Proper support ensures stability during experiments and allows for safe handling of heat sources or other equipment that may be used in conjunction with the flask.

While cleaning the flask before use is important for avoiding contamination and ensuring accurate results, it does not directly relate to the safety concerns associated with using the flask itself. Filling the flask to the brim is ill-advised due to the risk of spills and hazards associated with vigorous reactions, while using the flask without any support would create an unsafe environment, risking accidents. Thus, ensuring that the flask is properly supported is crucial for safety in the laboratory.