# Sample problems polymers with solutions

Question 1: How many moles of styrene (C₈H₈) would be needed to produce 1 mole of polystyrene, (C₈H₈)n?

Solution: To produce 1 mole of polystyrene, you would need n moles of styrene, as each styrene molecule becomes a repeating unit in the polymer. The exact value of n depends on the degree of polymerization.

Question 2: If the degree of polymerization of a given sample of polyethylene (C₂H₄)n is 5000, how many moles of ethylene (C₂H₄) were used to produce it?

Solution: If the degree of polymerization is 5000, then 5000 moles of ethylene were used to produce 1 mole of this sample of polyethylene.

Question 3: If you start with 0.05 moles of propene (C₃H₆) and obtain 0.01 moles of polypropene (C₃H₆)n, what is the degree of polymerization?

Solution: The degree of polymerization is the number of monomer units per polymer molecule, which would be (0.05 moles/0.01 moles) = 5.

Question 4: A polymer has a degree of polymerization of 2500 and the molar mass of the monomer is 28 g/mol. What is the molar mass of the polymer?

Solution: The molar mass of the polymer would be the degree of polymerization x molar mass of the monomer, which is (2500 x 28 g/mol) = 70,000 g/mol.

Question 5: How many grams of styrene (C₈H₈, molar mass = 104 g/mol) would you need to make 1 g of polystyrene, assuming complete conversion and a degree of polymerization of 1000?

Solution: If the degree of polymerization is 1000, then 1000 moles of styrene will form 1 mole of polystyrene. Therefore, to make 1 g of polystyrene, you would need (1000 x 104 g/mol) = 104,000 g of styrene.

Question 6: Given a sample of polypropene (C₃H₆)n with a mass of 42 g and a degree of polymerization of 1400, what is the molar mass of the sample?

Solution: The molar mass of the polypropene would be the degree of polymerization x molar mass of propene, which is (1400 x 42 g/mol) = 58,800 g/mol.

Question 7: A sample of polystyrene has a degree of polymerization of 3500 and a molar mass of 364,000 g/mol. What is the molar mass of the monomer?

Solution: The molar mass of the monomer is the molar mass of the polymer divided by the degree of polymerization, which is (364,000 g/mol ÷ 3500) = 104 g/mol.

Question 8: If you have 1 kg of ethylene (C₂H₄, molar mass = 28 g/mol), how many kg of polyethylene (C₂H₄)n could you theoretically produce, assuming 100% conversion?

Solution: Theoretically, 1 kg of ethylene could produce 1 kg of polyethylene, because the reaction doesn’t involve the loss or addition of any atoms.

Question 9: A copolymer is made from styrene (C₈H₈, molar mass = 104 g/mol) and acrylonitrile (C₃H₃N, molar mass = 53 g/mol). If the molar ratio of styrene to acrylonitrile is 2:1, what is the molar mass of the repeating unit?

Solution: The molar mass of the repeating unit is the sum of the molar masses of styrene and acrylonitrile, which is (2 x 104 g/mol + 53 g/mol) = 261 g/mol.

Question 10: Given a sample of polybutadiene (C₄H₆)n with a mass of 54 g and a degree of polymerization of 2200, what is the molar mass of the sample?

Solution: The molar mass of the polybutadiene would be the degree of polymerization x molar mass of butadiene, which is (2200 x 54 g/mol) = 118,800 g/mol.

Question 11: A 1 g sample of a polystyrene (C₈H₈)n has a degree of polymerization of 600. What is the mass of one monomer unit?

Solution: The mass of one monomer unit is the mass of the polymer divided by the degree of polymerization, which is (1 g ÷ 600) = 0.00167 g.

Question 12: If the degree of polymerization of polyvinyl chloride (C₂H₃Cl)n is 1100, how many moles of vinyl chloride (C₂H₃Cl) were used to produce it?

Solution: If the degree of polymerization is 1100, then 1100 moles of vinyl chloride were used to produce 1 mole of this sample of polyvinyl chloride.

Question 13: How many moles of ethene (C₂H₄) would be needed to produce 1 mole of polyethene, (C₂H₄)n?

Solution: To produce 1 mole of polyethene, you would need n moles of ethene, as each ethene molecule becomes a repeating unit in the polymer. The exact value of n depends on the degree of polymerization.

Question 14: A sample of polybutene (C₄H₈)n with a mass of 56 g has a degree of polymerization of 1500. What is the molar mass of the sample?

Solution: The molar mass of the polybutene would be the degree of polymerization x molar mass of butene, which is (1500 x 56 g/mol) = 84,000 g/mol.

Question 15: A polymer has a degree of polymerization of 3000 and the molar mass of the monomer is 30 g/mol. What is the molar mass of the polymer?

Solution: The molar mass of the polymer would be the degree of polymerization x molar mass of the monomer, which is (3000 x 30 g/mol) = 90,000 g/mol.

Question 16: How many grams of propene (C₃H₆, molar mass = 42 g/mol) would you need to make 2 g of polypropene, assuming complete conversion and a degree of polymerization of 2000?

Solution: If the degree of polymerization is 2000, then 2000 moles of propene will form 1 mole of polypropene. Therefore, to make 2 g of polypropene, you would need (2000 x 42 g/mol x 2) = 168,000 g of propene.

Question 17: Given a sample of polyvinyl chloride (C₂H₃Cl)n with a mass of 62 g and a degree of polymerization of 1300, what is the molar mass of the sample?

Solution: The molar mass of the polyvinyl chloride would be the degree of polymerization x molar mass of vinyl chloride, which is (1300 x 62 g/mol) = 80,600 g/mol.

Question 18: A sample of polypropene has a degree of polymerization of 2200 and a molar mass of 92,400 g/mol. What is the molar mass of the monomer?

Solution: The molar mass of the monomer is the molar mass of the polymer divided by the degree of polymerization, which is (92,400 g/mol ÷ 2200) = 42 g/mol.

Question 19: If you have 2 kg of propene (C₃H₆, molar mass = 42 g/mol), how many kg of polypropene (C₃H₆)n could you theoretically produce, assuming 100% conversion?

Solution: Theoretically, 2 kg of propene could produce 2 kg of polypropene, because the reaction doesn’t involve the loss or addition of any atoms.

Question 20: A copolymer is made from ethene (C₂H₄, molar mass = 28 g/mol) and propene (C₃H₆, molar mass = 42 g/mol). If the molar ratio of ethene to propene is 3:2, what is the molar mass of the repeating unit?

Solution: The molar mass of the repeating unit is the sum of the molar masses of ethene and propene, which is (3 x 28 g/mol + 2 x 42 g/mol) = 168 g/mol.

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