February 19, 2018 Useful Constants: R-0.082061-atr% , Multiple Choice: (30 Point
ID: 567515 • Letter: F
Question
February 19, 2018 Useful Constants: R-0.082061-atr% , Multiple Choice: (30 Points) mol ; k, (for H,0)--1.86mrC; kb (for H,O)-+0.5 12mTc Directions: Circle the letter corresponding to the most correct response 1. Which of the following processes (if any) is exothermic? a. Solid Gas b. Solid Liquid C. Liquid Gas d. Liquid Solid e. None of the above 2. Which of the following aqueous solutions is expected to have the highest boiling point (if any) a. 1m glucose (CsH120s b. 1m NacI c. 1m KNO e. They have the same boiling point 3. The liquids HO and CCl, are immiscible because a. The strong intermolecular forces which must be broken in H20 molecules b. The strong intermolecular forces which must be broken in CCl, molecules c. The strong polar bonds in the CCla molecule d. The weak dipole interactions in H20 e. The large difference in the molar masses of H20 and CCl 4. Which of the following would probably have the highest melting point? a. Clh b. NaCI c. MgCl2 d. CH4 e. CH3OH 5. What mass of Na CO, are contained in 0.400-L of a 0.250M Na CO, solution? a. 5.30-8 b. 10.6-g c. 15.3-g d. 20.8-g e. 24.2-gExplanation / Answer
1.The liquid converted to solid . The heat energy is released. so ti is exothermic reaction.
d. Liquid ---> solid
2. DTb = i*m*Kb
K2So4 ----------> 2K^+ (aq) + SO4^2-
i = 3
DTb = i*m*Kb
= 3*1*0.512
= 1.536C^0
The boiling point = 100+1.536 = 101.536C^0
3. H2O is polar lquid and CCL4 is non polar liquid
d. The weak dipole interations in H2O
4. NaCl is ionic compound. It has more lattivce enrgy . it is highest boiling point.
b. NaCl
5. no of moles of Na2Co3 = molarity * volume in L
= 0.25*0.4 = 0.1moles
mass of Na2Co3 = no of moles * gram molar mass
= 0.1*106 = 10.6g
b. 10.6g
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