Chemistry · Grades 10–12
Polymer repeat-unit mass model
Multiply repeat-unit molar mass by the number of repeat units. This simplified model ignores end-group masses.
Rule and assumptions
Multiply repeat-unit molar mass by the number of repeat units. This simplified model ignores end-group masses.
M(chain) ≈ repeat count × M(repeat unit)
Worked examples
Ignoring end groups in a supplied model, a polymer chain has 229 repeat units, each contributing 100 g/mol to the chain molar mass. Estimate that mass. Round to 3 decimal places if needed. Answer in g/mol.
M(chain) ≈ repeat count × M(repeat unit) 229 × 100 = 22900
22900 g/mol
Ignoring end groups in a supplied model, a polymer chain has 343 repeat units, each contributing 28 g/mol to the chain molar mass. Estimate that mass. Round to 3 decimal places if needed. Answer in g/mol.
M(chain) ≈ repeat count × M(repeat unit) 343 × 28 = 9604
9604 g/mol
Try two questions
Ignoring end groups in a supplied model, a polymer chain has 268 repeat units, each contributing 54 g/mol to the chain molar mass. Estimate that mass. Round to 3 decimal places if needed. Answer in g/mol.
Ignoring end groups in a supplied model, a polymer chain has 342 repeat units, each contributing 56 g/mol to the chain molar mass. Estimate that mass. Round to 3 decimal places if needed. Answer in g/mol.
Answers and reasoning
Answers and marking notes
- 14472 g/mol
M(chain) ≈ repeat count × M(repeat unit) 268 × 54 = 14472
- 19152 g/mol
M(chain) ≈ repeat count × M(repeat unit) 342 × 56 = 19152
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · independent educational and translation review required. Suggested grades are not official curriculum alignment.