Part 1: Multiple Choice (2 points each)Directions: Please circle the best answer for each of the following questions.Part 2: Short AnswerDirections: Answer each of the following questions. Be sure to use complete sentences where appropriate. For full credit be sure to show all of your work.Grossmont College Chemistry 141 Exam 4 Fall 2016Name: ___________________________________Date: ________Instructor: Diana VanceExam 4Part 1: Multiple Choice (2 points each) Directions: Please circle the best answer for each of the following questions. 1. In order for a solute to dissolve in a solvent, there must be:a. Ion-dipole forces between solvent molecules.b. Repulsion between solvent and solute molecules.c. Intermolecular attractions between solvent and solute molecules.d. Weak intermolecular forces between solute molecules. e. all of the above2. Fresh vegetables with high water content do not freeze well becausea. water expands when it freezes and damages the cell wall. b. water contracts when it freezes and damages the cell wall. c. water expands when it freezes and does not damage the cell wall.d. water contracts when it freezes and does not damage the cell wall. e. water does not change in size when it freezes. 3. Choose the substance with the lowest surface tension.a. CH3SeCH2CH3b. CH3CH2CH2CH3c. C6H6d. H2See. (CH3)2SO4. Which solute has the highest van’t Hoff factor?a. Nonelectrolyteb. KIc. MgSO4d. CaCl2e. AlCl35. Identify the element with the smallest band gap.a. Carbonb. Siliconc. Germaniumd. Leade. Oxygen6. Identify the type of interaction between atoms in a nonbonding atomic solid. a. Polar bondingb. Ionic bondingc. Covalent bondingd. Hydrogen bondinge. Weak dispersion forcesPage 1 of 7Grossmont College Chemistry 141 Exam 4 Fall 2016Name: ___________________________________Date: ________Instructor: Diana Vance7. Equilibrium for a chemical reaction is often called dynamic equilibrium because:a. a chemical reaction only truly stops when all reactants have been turned into products.b. a chemical reaction only seems to stop when it reaches equilibrium.c. reactants have changed into products, and dynamic means change. d. it is an important concept, and dynamic reminds us of this importance.e. the reactants and products are equal. Heating a metal carbonate leads to decompositionBaCO3 (s) ⇌ BaO (s) + 2 CO2 (g) Predict the effect on the equilibrium of the changes listed below. 8. adding BaCO3:a. no changeb. shifts leftc. shifts rightd. increases Te. none of the above9. decrease the volume of the flask containing the reaction:a. no changeb. shifts leftc. shifts rightd. increases Te. none of the above10. When using the safety shower for a large spill on yourself, you should:a. rinse for at least 15 minutes.b. avoid, it’s not that bad.c. keep contaminated clothes on.d. all of the abovee. none of the abovePage 2 of 7Grossmont College Chemistry 141 Exam 4 Fall 2016Name: ___________________________________Date: ________Instructor: Diana VancePart 2: Short Answer Directions: Answer each of the following questions. Be sure to use complete sentences where appropriate. Forfull credit be sure to show all of your work. 1. Explain what happens to a substance when it is heated in a closed container to its criticaltemperature (3 points). As the temperature rises, more liquid vaporizes and the pressure within the containerincreases. As more and more gas is forced into the same amount of space, the density of thegas becomes higher and higher. At the same time, the increasing temperature causes thedensity of the liquid to become lower and lower. At the critical temperature, the meniscusbetween the liquid and gas disappears and the gas and liquid phases commingle to form asupercritical fluid. 2. When a thin glass tube is put into water, the water rises 1.4 cm. When the same tube isput into hexane, the hexane rises only 0.4 cm. Explain (3 points). Water can general strong adhesive interactions with the glass (due to the dipoles at thesurface of the glass), but hexane is nonpolar and cannot interact strongly with the glasssurface. 3. Why isn’t pentanol (CH3CH2CH2CH2CH2OH) very soluble in water (4 points)?Even though the pentanol molecule contains a hydrogen bonding portion, the bulk of the bulkof the molecule is nonpolar and only exhibits dispersions forces. The majority of themolecules will not hydrogen bond to the water molecules, making it difficult to dissolve.4. A solution prepared from 1.25 g of oil of wintergreen (methyl salicylate, boiling point80.10 °C) in a 99.0 g of benzene (kb = 2.53 °C/m) has a boiling point of 80.31 °C. Determinethe molar mass of this compound (10 points). ∆ Tb=i kbm⇒ m=nsolutekgsolvent=∆ Tbikb=(80.31℃ −80.10℃ )(1)(2.53℃m)=(0.21 ℃ )(1)(2.53℃m)=0.083003953molkg solvent× 99.0 g solvent ×1 kg1000 g=0.008217391molMM=mn=1.25 g0.008217391 mol=152.1164021gmol≈ 150gmolPage 3 of 7Grossmont College Chemistry 141 Exam 4 Fall 2016Name: ___________________________________Date: ________Instructor: Diana Vance5. Silver crystallizes in a face-centered cubic unit cell. Each side of the unit cell has a lengthof 409 pm (6 points). a. What is the radius of a silver atom?l=2√2r ⇒r=l2√2=409 pm2√2=145 pm b. If the atomic radius of silver is 153 pm, what is the percent error? %error=observed value−true valuetrue value×100%error=145 pm−153 pm153 pm×100%error=−8 pm153 pm× 100=−5 %6. Suppose 651 g of ethylene glycol, HOCH2CH2OH, is dissolved in 1.50 kg of water. Whatis the vapor pressure of the water over the solution at 90 °C? The vapor pressure of purewater at 90 °C is 525.8 mm Hg. Assume ideal behavior for the solution (10 points). nwater=1.50 kg H2O×1000 g1 kg×1 mol H2O18.015 g H2O=83.3 mol H2Onglycol=651 g HOC H2C H2OH ×1 mol HOC H2C H2OH62.068 g HOC H2C H2OH=10.5 mol HOC H2C H2OHχwater=nsolventnsolution=nwaternwater+nglycolχwater=83.3 mol83.3 mol+10.5 mol=83.3 mol93.8 mol=0.888Psolution= χsolventPsolvent°Psolution=(0.888) (525.8 mmHg)=467 mm Hg∆ Pwater=Pwater°−Pwater=525.8 mm Hg−467 mm Hg=59 mm Hg7. Sketch the phase diagram of benzene. Make sure to label the axes and the differentphases of benzene. Use the physical data provided below (6 points).Melting point = 6 °CBoiling point = 80 °CTc = 289 °CPc = 36708 torrTriple Points = 38 torr, 6 °CStudents should show a graph of Pressure as a function of temperature. Label each phase assolid, liquid or