More Paper Clip Chemistry

Heather Haley
Product Developer
September 2015
Background
As discussed in our previous Carolina Tips® article “Paper Clip Chemistry,” paper clips are a great tool to explore a variety of chemistry concepts, including measurement, matter, atomic structure, chemical reactions, and gases.
If a wide variety of paper clips are available, you can use them to help students understand empirical formulas and relative masses. Suggested paper clips include:
Materials
- Mini Paper Clips (no. 3, box of 100)
- Small Paper Clips (no. 1, box of 100, item #971720)
- Large Paper Clips (jumbo, box of 100, item #971708)
- Owl Clips (also called regal clips, no. 3, box of 100)
- Butterfly Clips (also called ideal clamps, no. 1, 2 boxes of 50)
- Balances
Preparation
- Without counting, prepare samples of 2 clip types for each group. Suggested clip combinations include:
- Lg and Sm
- Lg and Mi
- Lg and Ow
- Bu and Lg
- Ow and Sm
- Bu and Sm
- Sm and Mi
- Bu and Mi
- Ow and Mi
- Bu and Ow
- Assign each group of students a set of 3 chemical equations to study. Each equation uses 2 types of paper clips abbreviated using a 2-letter symbol (analogous to a chemical element). Each equation set has the form:
Equation 1: Lg + Sm → LgSm
Equation 2: 2Lg + 2Sm → Lg2Sm2
Equation 3: 3Lg + 3Sm → Lg3Sm3
- Provide each group with a set of blank data tables to record their results and provide a framework for relevant calculations. Sample data tables follow each part of the procedure below.
- Determine your desired procedure for sharing class data with all students.
Procedure
Part 1: Paper clip data
Equation 1
- Use a balance to find the mass of each type of clip and record it.
- Connect 1 of each type of clip according to Equation 1. Continue connecting clips until 1 type of clip is used up.
- Find the mass of combined clip products and record it.
- Find the mass of any remaining clips in excess and record it.
Note: The total mass of clips before combining is the same as the total mass of combined paper clips and remaining paper clips, illustrating the law of conservation of mass.
- Unhook all combined clips.
Equation 2
- Use a balance to find the mass of each type of clip and record it.
- Connect 2 of each type of clip according to Equation 2. Continue connecting clips until 1 type of clip is used up.
- Find the mass of combined clips and record it.
- Find the mass of any remaining clips and record it.
- Unhook all combined clips.
Equation 3
- Use a balance to find the mass of each type of clip and record it.
- Connect 3 of each type of clip according to Equation 3. Continue connecting clips until 1 type of clip is used up.
- Find the mass of combined clips and record it.
- Find the mass of any remaining clips and record it.
- Unhook all combined clips.
Part 2: Conservation of mass and mass percent calculations
- Use the data in Table 1 to calculate the total mass of reactants and the total mass of products and excess reactants.
- Do the values you obtained support the law of conservation of mass?
- Use the data in Table 1 to calculate the mass of the first reactant used and the second reactant used.
- Copy the mass of product from Table 1.
- Do the values you obtained support the law of conservation of mass?
- Calculate the mass percent of each reactant using values in Table 2.
- What do you notice about the mass percent for each product in Table 2? What does this imply about the empirical formulas of each product?
Part 3: Class paper clip mass percent and mass ratios
- Locate the data you recorded for Equation 1 in Table 2.
- Locate the formula for your group’s Equation 1 product. Record this on the first row in Table 3.
- Copy the data for mass of first reactant used, mass of second reactant used, and mass of product from Table 2 to Table 3.
- Repeat steps 1–3 for data recorded for Equation 1 by other groups.
- Calculate the mass percent of each reactant using values in Table 3.
- Calculate the mass ratio for each reactant using values in Table 3.
Part 4: Class paper clip relative masses
- Identify the reactant with the smallest mass percent in Table 3.
- Set the mass of this reactant equal to 1.000 clip mass units (cmu).
- Use mass percent data from Table 3 to set up proportions and calculate the relative masses of each clip as follows:
Extension activity
- Assign each type of clip to represent an element (e.g., carbon = Ow, hydrogen = Sm, oxygen = Lg), and write the key in a location visible to students.
- Write down the chemical formulas for simple chemical compounds in a location visible to students. For example:
- CH2O, formaldehyde
- CH3OH, methanol
- C2H5OH, ethanol
- C6H12O6, glucose
- C3H7OH, isopropanol
- H2CO3, carbonic acid
- C2H4O2, acetic acid
- (CH3)2CO, acetone
- HCOOH, formic acid
- C4H10O, ethyl ether
- Ask groups to build 2–5 molecules of the compound of their choice, then disassemble the clips and place them in a plastic bag.
- Trade plastic bags between groups.
- Have each group determine the empirical formula of the compound in the bag using the relative mass of each clip from Table 4.
- If possible, have each group attempt to identify the chemical compound the first group used to place clips in the plastic bag.
Related items
- Inquiries in Science®: Reconstructing Atomic Theory Kit (item #251219)
- Inquiries in Science®: Determining Chemical Formulas Kit (item #251206)
- Carolina Investigations® for AP® Chemistry: Gravimetric Analysis of a Carbonate Kit (item #840570)
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