Which item spins very quickly within a solution to stir and accelerate the dissolving process?

• A. Laboratory Balance
• B. Pipetting Bulb
• C. Magnetic Stir Bar
• D. Safety Glasses

Answer: (C)

Stirring speeds up how quickly a solid dissolves by continuously bringing fresh solvent into contact with the solute. A magnetic stir bar placed inside the solution is designed for this purpose. When used with a stir plate, magnets beneath the plate spin the bar rapidly, creating a swirling motion that increases mixing, reduces the boundary layer around the solute particles, and accelerates dissolution. The other items have different functions in the lab: a laboratory balance measures mass, a pipetting bulb helps draw liquid into a pipette, and safety glasses protect the eyes.