Caffeine

1) heavier; having the extracting solvent as the bottom layer in a separatory funnel minimizes the number of transfers.

8) 90% Amount extracted = 0.90w0 = w0 - w0 (v1 / ((K (v2/n) +v1))n

0.10w0 = w0 (v1 / ((K (v2/n) +v1))n

Since v1 = v2/n and K = 0.5; assign v1 = 1 unit volume

0.10 w0 = w0 (1 / ((0.5 (1) +1))n = w0 (0.666)n

thus,

0.10 w0 = w0 (0.666)n

0.10 = (0.666)n

n = 5.6

6 extractions is needed.

9) Carbon dioxide gas is given off which will result in a pressure buildup in the separatory funnel. Frequent venting of the separatory funnel will prevent an excess pressure buildup. If not vented this pressure buildup can become explosive.

10) Given: V2 = 0.5 V1 and K = 2

thus,

amounted extracted into phase two = w0 - w0 (v1 / ((K (v2/n) +v1))n

substituting V1 into V2 we get,

= w0 - w0 (v1 / ((K (v2/n) +v1))n

= w0 - w0 (0.5)n

if n = 1,

= w0 - w0 (0.5)1 = 0.50 w0 or 50%

if n = 2,

= w0 - w0 (0.5)2 = 0.70 w0 or 75%

if n = 3,

= w0 - w0 (0.5)2 = 0.875 w0 or 87.5%

if n = 4,

= w0 - w0 (0.5)2 = 0.9375 w0 or 94%

11) Add NaCl (salting out).