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Name: KG[ CIRCLE your INSTRUCTOR/LECTURE TIME: McMills 8:35 am CIRCLE the alphabet segment of your last name: AE FL M-R Chemistry 1520 Exam IB Part I. (36 pts) Short Answer.
- (12 pts) Choose the correct answer for each of the following:
PID:
Paris 9:40 am Sz a. Ofthe IMF (intermolecular forces) listed, which is the WEAKEST? Circle one: dipole-dipole tondon dispersion force H-bonding dipole-induced dipole b. Which IMF Is associated with enthalpy of hydration (AHmya)? Circle one: dipole-dipole London dispersion forces H-bonding dipole-induced dipole
. Which IMF is responsible for O being partly soluble in H0? Circle one: dipole-dipole London dispersion forces H-bonding dipole-induced dipole d. For the compound sulfur hexafluoride, which is the STRONGEST IMF present? Circle one: dipole-dipole London dispersion forces H-bonding dipole-induced dipole February 14, 2025 100 points ion-dipole ion-dipole lon-dipole
. (12 pts) The cubic lattice of a particular ionic compound has the following features: There is ONE CATION {A) at each CORNER of the unit cell, There is ONE CATION (A) in each FACE of the unit cell. There are FOUR ANIONS {X) within the BODY of the unit cell. . The number of cations {A) per unit cell Is:
Grdeon: 12 3 (@) s & 7
. The number of anions (X) per unit cell is: Circle one: (^12 3) @ H (^678) The empirical formula of the compound is: Circle one: @ AXy (^) AX3 AXs
AaX AsX AsXz
. What unit cell do the cations adopt? Circle one: sc bee @
(14 pts) The element tantalum (Ta} adopts a bec unit cell. Glven that the density of Ta is 16.2 g/cm?, what is the radius of a single Ta atom, In cm? Report your answer to 3 significant figures. lue.^ x 2:“"”' (^) * (^) ‘—:‘u"ou( x (^) 8.9 (^) Radlus: o & (^) o "M.I (^) fere————p et 149 xio-Y ., x 3 lew? (^). 359%xlo (^) em? ~ Vs fl.‘ Py a‘J 3.5%94xl0 P03. 3.8gixtle om
- 4r r=al3 | 3.0 %l fum I3. I.‘flx‘°-9¢~h g (^4) [ ] (15 pts) A solution is prepared by dissolving 0.175 g of NaCl (MM = 58.44 g/mol) in 4.18 g of HCONH; {formamide). The boiling point of the NaCl/formamide solution is 215.5°C. Formamide has a molal boiling point constant, K of 3.85 *C/m. Calculate the bolling point of pure formamide in °C. Assume the solvent is nonvolatile and the sofution is ideal. Report your answer to one decimal place. Nactl L= Boiling point: o.l'-l:_, Nacl ¥ el Nacl 2 0.0029946 mel Nact 2io.0% £9.44%4 Nacd M1 0.0029948 mel Nael g et 4.18xl0 =? kj calv AT = 385°C^ ,^ o^ Hebmx^2 =^ 582° = _
AT = rhol'.---rbs.lv = $.82%¢
Toaeln (^) - (^) S.62°c = (^) Toal pubasia 2.18.$°c ~^ 6.%2°C^ a^ lfl.lo.o'c
Part Ill. Multiple Choice. Write answer on the line provided. (21 pts; 7 @ 3 pts each) A 1. Which of the following lons should have the smallest {least negative) enthalpy of hydration,
AHyya?
a. Cs* b. Rb* ¢, Ba® d. Sr** C 2. Which of the foliowing pairs is arranged with the particles of higher polarizability (^) listed first?
a i b. Mg, Mg c. Se?", 5% d.Br,
. Which of the following is expected to have the lowest vapor pressure at 350 K?
- 1.25 m K;S04 b. 1.00 m KsPO4 €. 1.50 m KNO3 d.1.25 mKCi D 4. Which is expected to have the lowest bolling point? a. 0.500 m NasPO, b. 1.25 m NaCl. 1.00 m Na2CO3 d. pure water C S. Carbonated drinks bubble when the bottie is opened because the temperature of the soda increases. exposure to atmospheric pressure squeezes the CO; from solution. the partial pressure of CO; above the solution is reduced. anocwatmospheric nitrogen molecules displace CO; molecules. 5_ 6. Which of the following palrs of liquids will be miscible (form a solution)? a. CClyand CH;0H €. H0 and CgHs b. CsHis and CeHig d. CaHis and H, :D 7. Asolution of sugar in water is in equilibrium with solid sugar. If additional solid sugar is added and the solution is stirred at constant temperature a supersaturated solution will form. the concentration of the solution will increase. the concentration of the solution will decrease. ap the concentration of the solution will remain the same. o
