In a polymer sample, 30% of molecules have a molecular mass of 20,000, 40% have 30,000 and the rest 60,000. What is the weight average molecular mass of the polymer ?

Question

In a polymer sample, 30% of molecules have a molecular mass of 20,000, 40% have 30,000 and the rest 60,000. What is the weight average molecular mass of the polymer ? (A) 40300 (B) 30600 (C) 43333 (D) 50400

Tardigrade Admin · Accepted Answer

barMw = (30(20000)2 + 40 (30000)2 + 30(60000)2/30 × 2000) + (40 + 30000)+(30 × 60000)) = 43.333

Q. In a polymer sample, 30% of molecules have a molecular mass of 20,000, 40% have 30,000 and the rest 60,000. What is the weight average molecular mass of the polymer ?

40300

30600

43333

50400

$\overset{ˉ}{M}_{w} = \frac{30 ( 20000 ) ^{2} + 40 ( 30000 ) ^{2} + 30 ( 60000 ) ^{2}}{30 \times 2000 ) + ( 40 + 30000 ) + ( 30 \times 60000 )} = 43.333$

Q. In a polymer sample, 30% of molecules have a molecular mass of 20,000, 40% have 30,000 and the rest 60,000. What is the weight average molecular mass of the polymer ?

40300

30600

43333

50400

Mˉw​=30×2000)+(40+30000)+(30×60000)30(20000)2+40(30000)2+30(60000)2​=43.333

$\overset{ˉ}{M}_{w} = \frac{30 ( 20000 ) ^{2} + 40 ( 30000 ) ^{2} + 30 ( 60000 ) ^{2}}{30 \times 2000 ) + ( 40 + 30000 ) + ( 30 \times 60000 )} = 43.333$