Solutions Worksheet - solvent, Lecture notes of Chemistry

Download Solutions Worksheet - solvent and more Lecture notes Chemistry in PDF only on Docsity! Solutions Worksheet - The Solution Process 1. Define the following: solution _____________________________ solvent _____________________________ solute _____________________________ Give an example of a common solution found in everyday life in each of the following phases. gas: _________________________ liquid: _______________________ solid: _______________________ 2. Although solutions can occur for any solvent and in any phase of matter, the most commonly encountered solutions are aqueous, i.e., in water. Therefore, we will consider the solution process more closely for aqueous solutions. a. In the beakers shown, use symbols to represent the appropriate compounds. i. pure water, □ ii. pure ethanol, ○ iii. a solution of ethanol in water, approximately 10% ethanol, 90% water 3. During this process, significant changes in the Intermolecular Forces of Attraction occur. List the IMF's present in each of the pure compounds. i. ___________________________________ ii. _________________________________ 4. In the solution, what IMF's are present. List what compounds are interacting and how. iii.__________________________________ ____________________________________ ____________________________________ 5. One way to view the changes in energy associated with formation of solutions is to break the solution process down into a series of steps. The various steps are listed below. For our example of ethanol in water, circle the appropriate enthalpy change. Base your answer on the IMF's present and how these will be affected. i. Separating some solvent molecules to make space available for the solute. ∆H1 is exothermic, endothermic or neither. Explain your answer. ________________________ ii. Separating all solute molecules from each other. ∆H2 is exothermic, endothermic or neither Explain your answer. ________________________ iii. Placing solute molecules in the available spaces in the solvent after step i. ∆H3 is exothermic, endothermic or neither Explain your answer. ________________________ The overall enthalpy change is the sum of the enthalpy changes for these three steps, ∆Hsoln = ∆H1 + ∆H2 + ∆H3 While each combination of solute and solvent will have a different value for ∆Hsoln, as a general trend, a solution will form if ∆Hsoln is exothermic and will not form is ∆Hsoln is highly endothermic. Since ∆H1 and ∆H2 are ALWAYS endothermic, the magnitude of ∆H3 is critical in determining solubility. If the IMF's formed between solute and solvent are of comparable magnitude to those broken, the solute will usually be soluble in that solvent. Exactly how much solute will dissolve before the solution becomes saturated is also determined by these relative strengths of IMF's. This type of analysis is often summarized in the common statement: "Like dissolves like." Based upon the ideas illustrated above, complete the following tables of solubilities. Solvent Solute soluble or insoluble compound polar or nonpolar? compound Ionic? Molecular? (if yes, polar or nonpolar)? water Polar KCl ionic soluble water NH4NO3 water glucose* water C10H8 hexane, C6H14 water hexane C10H8 gasoline sucrose (a sugar) * the structure of glucose is OH OH OH O OH OH