The solubility of caffeine in water at 0 degrees celsius is 0.022 g/mL. This mea
ID: 987773 • Letter: T
Question
The solubility of caffeine in water at 0 degrees celsius is 0.022 g/mL. This means that for every mL of water, 0.022g of caffeine will dissolve. A student wanted to separate a heterogenous mixture containing 2.0g of NaCl and 4.0 g of caffeine. She added 100 mL of water to dissolve all of the salt and cooled the mixture to 0 degrees celsius. Answer the following questions:
a) How much caffeine also dissolved in the water?
b) Assuming no additional losses, calculate the maximum % recovery for caffeine. (Hint: The student would recover none of the caffeine dissolved in the water.)
c) Whar could the student do next time to maximize her % recovery for caffeine?
Explanation / Answer
a.solubility of caffeine 0.022g/ml means every 1ml of water 0.022g of caffeine dissolve
1ml of water dissolve 0.022gm caffeine
100ml of water dissolve = 0.022*100/1 =2.2 gm
out of 4gm of caffeine 2.2gm of caffeine dissolve in 100ml of water.
The recovery of caffeine = 4-2.2 = 1.8gm
Maximum %recovery = 1.8*100/4 = 45% recovery