Isolate the Product (cont.)

• Once the solution has cooled, scratch the bottom of the beaker with a glass stir rod to release small crystals attached to the glass and promote further crystal growth

• Allow crystals to form undisturbed in the ice-water bath for an additional 5 minutes

(Pro-tip: crystals tend to form when you’re not watching them!)

• If necessary: add a seed crystal if crystals do not form within a few minutes after scratching the beaker

• Set up the vacuum filtration apparatus while crystals continue to form and pre-weigh the filter paper

• Vacuum-filter the product using a Buchner funnel

• Let the solid dry on the filter paper with the vacuum on for 10 minutes

• Weigh the amount of product on the filter paper

mass of product = (mass of product + filter paper) – (mass of filter paper)

1. Calculate the experimental yield (mg):

   • (theoretical yield) – (sum of product losses)

2. Calculate the percent yield:

   • (experimental yield / theoretical yield) x 100