hw2 - calvert (lmc2923) – Homework 2 – clinger –...

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Unformatted text preview: calvert (lmc2923) – Homework 2 – clinger – (20682) 1 This print-out should have 24 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Which of the following solutes is likely to be most soluble in water? 1. ethanol (CH 3 CH 2 OH) correct 2. Br 2 3. carbon tetrachloride (CCl 4 ) 4. CS 2 Explanation: 002 10.0 points Which is the best representation of the solva- tion of a sodium cation in water? hydrogen oxygen Na + ion 1. correct 2. 3. 4. Explanation: Since the water molecule has a partial neg- ative charge on the O atom, it will orient itself to the O atom closest to the positively charged cation. calvert (lmc2923) – Homework 2 – clinger – (20682) 2 003 10.0 points An aqueous solution is analyzed and found to contain potassium ions and sulfite ions. Write the equation for the dissolution of the salt that produced this solution. If the solution contains 0.700 mol of potassium ions, how many moles of sulfite ions are present? Correct answer: 0 . 35 ol. Explanation: ions produced are K + and SO 2 − 3 n K + = 0 . 7 mol solvent is H 2 O salt that produced the solution = ? n SO 2- 3 = ? mol K 2 SO 3 (s) H 2 O----→ 2 K + (aq) + SO 2 − 3 (aq) where K 2 SO 3 is the salt. (0 . 7 molK + ) parenleftBigg 1 mol SO 2 − 3 2 mol K + parenrightBigg = 0 . 35 ol SO 2+ 3 004 10.0 points Which of the following substances would you expect to be most soluble in water? 1. CH 3 OH (methyl alcohol) correct 2. CH 4 3. CH 3 OCH 3 (dimethyl ether) 4. CH 3 CH 3 (ethane) 5. All are equally soluble Explanation: Like dissolves like, so molecules with inter- molecular forces most like those for water are most likely to dissolve be soluble) in water. Molecule Intermolecular Forces (in order of increasing strength) H 2 O O b b b b H H dispersion, dipole-dipole, H-bonding CH 4 C H H H H dispersion CH 3 CH 3 C H H H C H H H dispersion CH 3 OCH 3 C O H H H C H H H b b b b dispersion, dipole-dipole CH 3 OH C O H H H H b b b b dispersion, dipole-dipole, H-bonding The molecule with intermolecular forces most like water is CH 3 OH, so CH 3 OH is most soluble in water (of those listed). 005 10.0 points The process by which solvent molecules sur- round and interact with ions or molecules is called 1. hydration. 2. None of these 3. condensation. 4. solvation. correct Explanation: Hydration is solvation in which the solvent is water. Condensation is the physical change of a substance from gaseous to liquid state. 006 10.0 points Calculate the number of moles of oxygen that will dissolve in 45 L of water at 20 ◦ C if the par- tial pressure of oxygen is 0.21 atm. Henry’s calvert (lmc2923) – Homework 2 – clinger – (20682) 3 constant for oxygen is 0.0013 mol L · atm ....
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hw2 - calvert (lmc2923) – Homework 2 – clinger –...

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