% Composition of a Penny Lab
(1 of 4)
• DMA: Observe the reactions of hydrochloric
acid, HCl, with both copper & zinc. What is
the difference?
• A penny is composed of copper around zinc.
Estimate the % of copper & zinc in a penny.
• Re-estimate at the end of class.
% Composition of a Penny Lab
(2 of 4)
• Materials: digital scale, metal file, penny, 25ml of 6M
HCl/penny, 100 ml beaker
• Given the materials above, write procedures that
would allow you to determine the % of copper and
zinc in a penny.
Day 1 – Procedures (3 of 4)
1.
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Make data table as directed.
Observe penny’s year & condition.
Weigh penny on digital scale.
File copper off side of penny at 4 spots to expose
zinc.
Label beaker w/ initials & period.
Pour 25 ml of 6M HCl into beaker. (50 for 2)
Place both pennies in the acid & observe.
Store overnight in cabinet.
Day 2 Procedures
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Observe the condition of the pennies repeatedly.
Decant the liquid into the hazardous waste.
Rinse out penny with water & pour down the sink
Dab dry the penny with a paper towel & on the hot
plate for several minutes.
5. Remass the pennies.
6. Tape the hollow penny into your lab notebook as
proof of completion.
7. Show your lab notes & hollow penny to the
instructor for a grade.
% Composition of Penny Lab Report (1
of 2)
Include:
Title
Prelab Observations (DMA)
Purpose
Hypothesis
Materials
Step by Step Procedures
Data Table with Item/Measurements/Observations
% Composition of Penny Lab Report (1
of 2)
Calculations – Item / Formula / Work / Answer
for each.
Sources of Error – Real ones /not maybes or
could haves.
Conclusions – Restate hypothesis, evaluate
hypothesis, use #s to justify your evaluation,
relate lab to real life beyond pennies.