The Gold Penny Lab

In this lab, you will be converting a regular penny into a “gold” penny. In doing so, you are following a tradition that goes back to the earliest days of chemistry.

The modern practice of chemistry started with the study of alchemy in medieval Europe and the Middle East. Alchemists believed that by doing certain chemical reactions, you could turn cheap metals into gold. Some of them did, anyway- the others would convince people that they could do this and sell them the secret. By the time anybody realized that the “Secret” didn’t work, they’d be long gone with the money.

In this lab, you’ll be doing a reaction in which copper appears to turn into gold. You’ll also test to see if you always get those results.

Safety:

In this lab, it is very important that you wear your goggles at all times and work with the chemicals carefully. The chemicals that we are working with are extremely dangerous and can cause serious injury.

Experiment:

  1. If your pennies appear dirty, scrub them with a test tube brush or steel wool. You need a shiny penny for the next steps.
  1. Record the initial appearance of the penny.
  1. Mass out 0.5 g of granular zinc. Put this amount of zinc into an evaporating dish.
  1. Measure 15 mL of NaOH solution. Pour this into the evaporating dish to cover the zinc.
  1. Heat the dish and its contents so that the solution is gently simmering.
  1. Carefully add the penny to the solution and allow to simmer for 1 minute.
  1. After 1 minute, turn the penny over and allow it to simmer for another minute, or until you observe a uniform color.
  1. Remove the penny form the dish and drop the penny into a beaker of water.
  2. Dry the penny with a paper towel.
  1. Record the appearance of the penny.
  1. Using the tongs, hold the penny heads up in the flame of the Bunsen burner for 3 seconds. Remove from heat, flip the penny and re-heat tails side up for another 3 seconds. Repeat carefully until you see a color change. WARNING: Pennies will melt if left in the fire too long! The zinc core of a penny melts easily!
  1. Set the penny on the bench top to cool. Rinse the penny a second time.
  1. Record the appearance of the finished penny.

Repeat the experiment:

Do the experiment over again, except this time change something about the way you did it. Change only one thing!!

Background Information:

Do some research on alloys…are they elements, compounds, or mixtures?

What are some common ones?

What alloy was involved in this lab and how was it created?

Are chemical reactions the same as nuclear reactions?

Conclusion:

Write a conclusion paragraph, paying attention to the features of a good conclusion:

  • State your results. Discuss if you met your objective.
  • Analyze your results. Were they accurate? Precise?
  • State and Analyze your errors. What ere the errors and how did they change your results?

To help you, you can also consider some of these questions (but write them into a paragraph!!!):

  • Were you able to change a penny into gold? Why?
  • How gold did it look?
  • What might have happened to pennies that didn’t look very gold?
  • Did the changed procedure yield the same results as before? Why?
  • Why do you think you got a different result the second time you did the experiment?