Brass Penny Lab

 

 

Introduction

 

In this lab you will be coating a copper penny with zinc metal and then heating the coated penny to allow the copper and zinc to mix together to form brass.� This lab involves heating a solution of sodium hydroxide (NaOH). �Be very careful not to let the sodium hydroxide solution come into contact with your skin.� WEAR YOUR GOGGLES AT ALL TIMES THROUGHOUT THIS LAB!

 

 

  1. Purpose:� The purpose of this lab is to create brass, which is an alloy (a homogeneous mixture) of copper and zinc.

 

  1. Procedure:

 

  1. Place 2 copper pennies (each with a different minting year) in a 1.0M HCl (hydrochloric acid) solution for 1-2 minutes.� Observe the chemical reaction that occurs as the oxidation is removed from the penny.
  2. Remove the pennies with crucible tongs and rinse with distilled water.� Dry with a paper towel.� Do not touch the pennies with your hands.
  3. Record the mass of each penny.
  4. In a clean evaporating dish, mix 1.0 g of granular zinc, your 2 pennies, and 25. ml of 3.0M NaOH.� Cover the evaporating dish with a watch glass.� Carefully heat the mixture until it begins to steam and boil gently.� Do not allow the solution to boil too strongly!
  5. Continue to heat the pennies in the Zn/NaOH mixture until the pennies are completely coated with zinc.� Move the Bunsen burner away from the evaporating dish.
  6. Remove the coated pennies from the Zn/NaOH mixture using the crucible tongs and dip the pennies into a beaker of distilled water.
  7. Using the crucible tongs, carefully and gently heat each coated penny in a Bunsen burner flame until the zinc coating has mixed with the copper to form a brass penny.� This only takes a few seconds!
  8. Dip each brass penny into a beaker of distilled water.� Dry the penny and record its mass.

 

III.               Data:�������� Create a data table showing your data (and possibly the data of others).

 

  1. Calculations:� Determine the percentage of zinc in the brass penny.