P1: Trim: 8.375in × 10.875in

LWBK575-20-Stud-Ans LWW-Sinko-educational March 16, 2010 11:2

A N S W E R S T O P R A C T I C E P R O B L E M SF O R S T U D E N T U S E

CHAPTER 20: PHARMACEUTICAL POLYMERS

20–1 (b)

20–2 (c)

20–3 (b)

20–4 (d)

20–5 (d)

20–6 (b)

20–7 (b)

20–8 (c)

20–9 (e)

20–10 (a)

20–11 (a)

20–12 (d)

20–13 (b)

20–14 (d)

20–15 (d)

20–16 50,000 (49,500 has three significant figures, which ismore than the M values of the input).

20–17 Mz = 401,000; Mw = 162,000; Mn = 43,500;and Mw/Mn = 3.73.

20–18 The intrinsic viscosity of polyethylene oxide willdecrease, as higher temperature favors polymer–polymer interactions and reduces the polymer–waterinteraction. Higher temperature results in partialto incomplete insolubility of polyethylene oxide inwater.

20–19 Decreasing trend of the melting point is associatedwith decreased intermolecular interactions as the sizeof the pending group increases.

20–20 (b)

20–21 (a)

20–22 (d)

20–23 (b)

20–24 (e)

1