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Movie Size - 1.8 MB Movie Duration - 63 Seconds File - CCA6/MOVIES/volumetric/DISH3_4.MOV

Discussion

Students should watch this movie carefully to observe all of the subtle manipulations used to insure the solid is quantitatively transferred from the dish to the volumetric flask.

A metal paper clip should not be used if the solution or the solvent is corrosive. An alternative is required.

Narrative

Now we do something a bit odd. We open a paper clip and hang it on the neck of the flask and then we add our funnel. The paper clip creates an air gap between the funnel stem and the flask allowing for better solution flow.

The solid is now quantitatively transferred to the funnel. The weighing dish is never moved from above the funnel during the solid transfer. We use large amounts of deionized water to rinse any solid remaining in the dish down into the funnel.

By now we have a solution of the solid in the weighing dish. We want to transfer all of it to the flask.

A solution droplet may have worked its way behind the dish delivery lip. We rinse there just in case.

We now assume that all of the solid has been transferred from the dish to the funnel.