Question 7.C-L.2: Refer to Figure 7.3. Saturated solutions of potassium nitrat...
Refer to Figure 7.3. Saturated solutions of potassium nitrate (KNO_3) and sodium bromide (NaBr) are made at 80°C. Which solution contains more solute per 100 g of H_2O ? The solutions are cooled to 50°C, and excess solute crystallizes out of each solution. Which solution at 50°C contains more solute per 100 g of H_2O ? Are the solutions saturated at 50°C?
At 80°C, a saturated solution of KNO_3 contains about 181 g of solute/100 g of H_2O, and a saturated solution of NaBr contains about 118 g of solute per 100 g H_2O. At 50°C both solutions are still saturated, but the KNO_3 solution contains only about 102 g of solute per 100 g H_2O, while the NaBr solution contains about 117 g of solute per 100 g H_2O. Thus, the solubility of KNO_3 is seen to be much more temperature dependent than the solubility of NaBr .