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Discussion

Manual mixing is a quick method to prepare a homogeneous mixture. Manual mixing is often used for solutions in which little or no reaction is taking place (a solution that will be stored for later reaction). Manual mixing is also convenient for mixing small volumes or for mixing reactions that go to completion quickly. Some examples of manual mixing techniques are included below.

Gently Striking the Side of the Container:
Small volumes in a test tube can be mixed by gently striking the side of the test tube with a finger or short length of rubber tubing. When the mixture will not react with a stopper, the test tube can be stoppered and shaken to mix the contents. NEVER use your finger as a stopper.

Shaking the Container:
A closed container can be shaken only if no gas will be formed as a result of the mixing (the increased pressure is a safety hazard). Shake the container and its contents until a homogeneous mixture is achieved. NEVER use your finger or hand to seal a container that will be shaken.

Swirling the Container:
To swirl the container, lift the container and move the base of the container in small circles. With some practice a small vortex will form. Generally, it is not a good practice to swirl solutions in wide-mouthed container such as a beaker, since splashing might occur. Instead, use an Erlenmeyer flask. An Erlenmeyer flask is designed to allow swirling with a minimal risk of splashing.

Narrative

To mix gently, strike the lower portion of the test tube a little off center while holding the top of the tube.