How to Tell if Lead Is Pure

In order to find out if something is pure, you need a base from which to work. Lead, luckily, is an element, and elements have physical properties that can be used to determine if they are pure. Lead is a dull-colored, malleable metal. To figure out if lead is pure, you will use a method that was most famously used by Archimedes in Ancient Greece: You will figure out the density of your substance by using water displacement and a balance. The density of lead is 11.34 grams per milliliter (mL), so your sample must have this density or it is not pure.

Things You'll Need

• Analytical balance
• Graduated cylinder
• Calculator

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Instructions

1. • 1

     Remove a sample of your substance that is small enough to fit in your graduated cylinder.

   • 2

     Zero your balance, then place the sample on it. Record this number (in grams) as the mass of your sample.

   • 3

     Fill the graduated cylinder to a level that will completely cover your sample. Record the volume (in mL) at the meniscus (the dip in the center of the water). This is the original volume.

   • 4

     Drop the sample into the graduated cylinder carefully. Record the final volume at the meniscus.

   • 5

     Subtract the final volume from the original volume using your calculator. Record this number. This is the volume of your sample.

   • 6

     Divide the mass of the sample by the volume of the sample. This number is the density of your sample. If it is pure lead, it must be 11.34 g/mL.