Molecular mass of polymers

35 questions on Molecular mass of polymers from the Polymers chapter: 5 NEET level, 16 JEE Main, 14 JEE Advanced. Each one opens with its answer and solution.

• Nylon 6,6 has the repeat unit -[NH-(CH2)6-NH-CO-(CH2)4-CO]-, molecular formula C12H22N2O2. Taking C = 12, H = 1, N = 14, O = 16, calculate the number-average de... JEE Main level
• A sample of polymer has M_n = 5.0x10^4 g mol^-1 and M_w = 8.0x10^4 g mol^-1. Its polydispersity index M_w/M_n is JEE Main level
• Which statements about the degree of polymerisation are correct? (C = 12, H = 1, N = 14, O = 16) JEE Advanced level
• The degree of polymerisation of a polymer chain is NEET level
• A sample of 1 mol chains of 100000 g mol^-1 is mixed with 1 mol of short chains of 1000 g mol^-1. Compared with the original sample, which are correct? JEE Advanced level
• A sample has 2 mol of chains of molar mass 20000 g mol^-1 and 1 mol of chains of molar mass 50000 g mol^-1. Using M_n=sum N_iM_i/sum N_i, M_w=sum N_iM_i^2/sum N... JEE Advanced level
• A blend contains 6.0 g of one species of chain of 20000 g mol^-1 and 6.0 g of another species of 60000 g mol^-1. Which are correct? JEE Advanced level
• A blend contains 10 g of polymer of molar mass 10000 g mol^-1 (one species) and 10 g of polymer of molar mass 40000 g mol^-1 (one species). Use M_n=sum N_i M_i/... JEE Main level
• A sample of polystyrene (repeat unit -[CH2-CH(C6H5)]-, taken as 104 g mol^-1) has M_n = 1.04x10^5 g mol^-1. The number-average degree of polymerisation is JEE Main level
• A sample of poly(vinyl chloride), repeat unit -[CH2-CHCl]- (C = 12, H = 1, Cl = 35.5), consists of 120 chains of molar mass 15000 g mol^-1, 200 chains of 35000 ... JEE Advanced level
• A polymer sample in which every chain has exactly the same molar mass has a polydispersity index M_w/M_n equal to NEET level
• Which statements about molar mass averages of polymers are correct? JEE Advanced level
• Which sample is expected to have a polydispersity index closest to 1? JEE Main level
• A sample contains 2 mol of chains of molar mass 15000 g mol^-1 and 1 mol of chains of molar mass 45000 g mol^-1. Use M_w = sum N_i M_i^2 / sum N_i M_i. The weig... JEE Main level
• For any polymer sample, which statement about M_w and M_n (as defined by M_n=sum N_iM_i/sum N_i and M_w=sum N_iM_i^2/sum N_iM_i) is correct? JEE Main level
• A sample has 1 mol of chains of 10000 g mol^-1 and 1 mol of chains of 30000 g mol^-1. Which are correct? JEE Advanced level
• Osmometry (a colligative method) and light scattering are used to measure molar mass of polymers. They give, respectively, JEE Main level
• The polydispersity index (PDI) of a polymer sample is defined as NEET level
• The degree of polymerisation of a homopolymer is NEET level
• Membrane osmometry, a colligative-property method, directly gives the NEET level
• A sample has equal numbers of chains of molar mass 10000 g mol^-1 and 30000 g mol^-1. Using M_w = sum N_iM_i^2/sum N_iM_i, its weight-average molar mass in g mo... JEE Main level
• Which technique gives the weight-average molar mass M_w of a polymer? JEE Main level
• Which sample would be expected to have a polydispersity index very close to 1? JEE Main level
• A polymer has M_w = 1.00x10^5 g mol^-1 and PDI =2.00. Its M_n in g mol^-1 is JEE Main level
• Nylon 6,6 has the repeat unit -[NH(CH2)6NHCO(CH2)4CO]- (formula C12H22N2O2, C 12, H 1, N 14, O 16). A chain of molar mass 22600 g mol^-1 (end groups ignored) co... JEE Main level
• Equal masses (50 g each) of two monodisperse fractions of molar mass 10000 and 40000 g mol^-1 are mixed. The number-average molar mass in g mol^-1 is JEE Main level
• Select all the correct statements. JEE Main level
• Poly(methyl methacrylate) has the repeat unit -[CH2-C(CH3)(COOCH3)]- (formula C5H8O2; C 12, H 1, O 16). A sample has a molar mass of 183700 g mol^-1. Ignoring e... JEE Main level
• A linear polyester has a carboxyl group at each end of every chain. A 2.0 g sample needs 4.0 mL of 0.100 M NaOH for complete neutralisation of the carboxyl grou... JEE Advanced level
• A sample consists of two monodisperse fractions: 30% by mass has M=20000 and 70% by mass has M=80000 g mol^-1. Using M_n=sum N_iM_i/sum N_i, M_w=sum N_iM_i^2/su... JEE Advanced level
• A nylon 6 chain has a molar mass of 56500 g mol^-1 (end groups ignored). The repeat unit is -[NH(CH2)5CO]- (formula C6H11NO; C 12, H 1, N 14, O 16), formed by r... JEE Advanced level
• Equal moles of chains of M=1.0x10^5 and of M=1.0x10^3 g mol^-1 are mixed (instead of the pure 1.0x10^5 sample). Compared with the pure sample, the mixture shows JEE Advanced level
• A sample has 2.00 mol of chains of M=1.0x10^4 and 1.00 mol of chains of M=4.0x10^4 g mol^-1. Using M_n=sum N_iM_i/sum N_i, M_w=sum N_iM_i^2/sum N_iM_i and PDI =... JEE Advanced level
• Select all the correct statements about determination of molar mass of polymers. JEE Advanced level
• A polymer sample contains 400 chains of molar mass 2.0x10^4, 400 chains of 5.0x10^4 and 200 chains of 1.0x10^5 g mol^-1. Use M_n=sum N_iM_i/sum N_i, M_w=sum N_i... JEE Advanced level