Composition of a Penny Lab 1 of 4

% 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, 25 ml of 6 M 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. 2. 3. 4. 5. 6. 7. 8. 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 6 M HCl into beaker. (50 for 2) Place both pennies in the acid & observe. Store overnight in cabinet.

Day 2 Procedures 1. 2. 3. 4. 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.