I I Name Date Class _ APPLYING SCIENTIFIC METHODS IN CHEMISTRY SOLUBILITY .• To investigate how solubility changes as solvent temperature changes, Lisa first put 100 g of water, at O°C, in a beaker. While keeping the temperature of the water constant, she slowly added the compound and stirred vigorously. Once she had added 180 g of the compound, undissolved crystals remained on the bottom of the beaker. Lisa filtered the mixture to reclaim the undissolved crystals, which she dried and found to have a mass of 2 g. Lisa then heated the solution to 10°C. While stirring the solution, she added more of the compound. After adding 10.5 g of the compound, she found that crystals remained undissolved. Temperature (OC) Solubility (per 100g ~O) 0 178 10 187 20 209 30 222 40 236 50 261 60 290 Following the same procedure as before, she reclaimed 1.5 g of crystals. Thus, 187 g of crystals had dissolved.. Lisa repeated the procedure while heating the solution in increments of 10°C. Her data table is shown here. 320 300 6' 280 I Ol 260 0 0 ..- Qj 240 -S (5 (f) .9 220 ~ .s 200 ::J (5 rn 180 160 0 10 20 30 40 50 60 70 Temperature (0C) 1. Construct a best-fit solubility curve for the compound Lisa tested by plotting her data on the graph grid provided. 2. Based on the data, what can you conclude about the relationship between the temperature of the solvent and the solubility of the unknown compound? 3. Looking at the shape of the curve in your graph, describe how the amount of compound that is soluble changes as the temperature increases. 4. Based on your graph, predict the solubility of the compound in water at 70°C. _ 5. What kind of solution formed each time the maximum amount of compound was dissolved at a given temperature? 6. As a result of heating in each case, what kind of solution then was formed? _ 7. a. What kind of solution would be formed if Lisa allowed the solution to cool from 60°C to 50°C? b. Would the solution be stable? _ :>- c .• a. E ° u C> c ~ ,!! :c " a. '0 ° .c c (f) I ~ 5 ~ ~ 'e u .• :;; '0 c ° ';;; 's i5 " ° c c .• c; " -5 ~ Q 1: ,g> ~ ° u 40 APPLYING SCIENTIFIC METHODS IN CHEMISTRY Chapter 20