CHEM 1128Q Lecture Notes - Lecture 3: Boiling-Point Elevation, Freezing-Point Depression, Boiling Point

T. The solublity of ones fn re and decreasing pressuure (1) increasing pressure and increasing temperature (3) decreasing temperature and increasing pressure (2) ally decreases with increasing temperature and decreasing pressure (4) decreasing temperature and decreasing pressure. 8. When a nonvolatile solute s uch as ammonium sulfate is dissolved in a solvent like water, one of the (1) a decrease in the boiling point of the liquid (2) an increase in the vapor (4) a decrease in the observed effects is pressure of the solvent freezing point of the liquid (3) an increase in the vapor pressure of the solute . In which of the following solvents would you expect kBr to be most soluble? (1) CClu (carbon tetrachloride) 0. Calculate the mass percent of HOCH-CH2OH in a solution made by dissolving 6.4 g of HOCHCH20H in 11. During osmosis (1) pure solutes diffuse through a membrane but solvent does not (2) pure solvent (2) CHsCH2OH (ethanol) (3) CaHe (benzene (4) CoH14 (hexane) 48.2 g of water. (1)13.3% (2) 6.9% (3) 7.4% (4) 11.7% diffuses through a membrane but solutes do not (3) pure solvent and a solution both diffuse at the same time through a membrane (4) gases diffuse through a membrane into a solution and build up pressure 12. Which of the following gases is expected to have a highest solubility in water? (1) HCI (2) N2 (3) CH (4) O2 13. How many grams of water are needed to dissolve 27.8 g of ammonium nitrate NH NOs in order to prepare a (1)0.157 g (2) 769 g (3) 36.2 9 0.452 m solution? The molar mass of NH4NOs is 80.04 g/mol. (4) 57.0 g (1) enough solvent to make 14. To make a 3.0 m solution, one could take 3.00 moles of solute and add L of solution (2) enough solvent to make 1.00 kg of solution (3) 1.00 L of solvent (2) 1.00 kg of solvent 15. What volume of 2.00 M CHOH solution is needed to provide 0.500 mol of CHJOH? (1)3,.12 mL (2) 10.0 mL (3) 167 mL (4) 250 mL 16. Assuming 100% dissociation, which ofthe follow ng compounds is listed correctly with its van't Hoff factor? (4) Ala(SO4), i-5 (2) NH4N03, i#3 (3) Sucrose, i:0 (1) NaS0+/-2 17. Calculate the van't Hoff factor of NasPO in a 0.40 m solution whose freezing point is -2.6C. 15 pts]

Boiling point point Boiling of water of sol Temperature Freezing point Freezing point of water of solution Like vapor pressure lowering, bo Quantifing boiling concentration of solute: on is proportional to the Kbrn or ATI ATH 2. the solution and K is the molal boiling point ee Cona ybtract the lower solvent 7b from the higher solution AT Tbosolution) Tb solvent), use it relates to mole fraction and, thus, to particles of eted by temperature Celsius per molal unit (Cum) and is Ab units of degrees water is 0.512 m, so AT for solvent (Table 13.6). for of glucose lutions is small. For example, if you dissolve 1.00 mol Molal Boiling Point Elevation and Freezing Point Depression Table 13.6 Constants of Several Solvents Boiling Point (°C)* Kb(CIm) Melting Point (C) Ki(clm Solvent 16.6 3.07 Acetic acid Benzene 80.1 2.53 5.5 Carbon disulfide 46.2 2.34 Carbon tetrachloride 76.5 5.03 23 Chloroform 61.7 470 3.63 63.5 Diethyl ether 34.5 119 2.02 116.2 Ethanol 78.5 1.22 Water 100.0 0.512 At 1 atm. Freezing Point Depression A solution freezes at a lower temperature than l. and this property also results from vapor lowering solute Why a freezes at a lower ure solution s molecules are left T. Only solvent vaporizes from behind, Similorlu