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CHEM |! 151 |! Exam |! 4 |! with |! verified |!
detailed |! solutions
Ionic |! compound |! - |! Correct |! answer |! ✔composed |! of |! positive |! and |! negative |! ions |! that |! are |! combined |! so |! that |! the |! numbers |! of |! positive |! and |! negative |! charges |! are |! equal What |! types |! of |! ions |! (anions |! = |! - |! or |! cations |! = |! +) |! do |! metals |! form? |! Justify |! your |! reasoning. |! - |! Correct |! answer |! ✔Metals |! have |! low |! electronegativities. |! Because |! of |! this, |! metals |! are |! more |! likely |! to |! give |! up |! (or |! lose) |! their |! electrons |! to |! become |! + |! ions |! (cations) Another |! way |! to |! justify |! this |! would |! be |! to |! use |! their |! electron |! configurations. |! Na |! = |! 1s22s22p63s1 |! so |! the |! most |! likely |! ion |! to |! form |! would |! be |! one |! with |! a |! noble |! gas |! electron |! configuration |! or |! one |! with |! a |! filled |! valence |! shell. |! The |! easiest |! way |! to |! do |! that |! is |! to |! lose |! that |! one |! electron |! in |! the |! 3s. |! Losing |! electrons |! make |! the |! ion |! positive |! (cation). What |! types |! of |! ions |! (anions |! = |! - |! or |! cations |! = |! +) |! do |! nonmetals |! form? |! Justify |! your |! reasoning. |! - |! Correct |! answer |! ✔Nonmetals |! have |! high |! electronegativities. |! Because |! of |! this, |! nonmetals |! are |! more |! likely |! to |! gain |! electrons |! to |! become |! - |! ions |! (anions). Another |! way |! to |! justify |! this |! would |! be |! to |! use |! their |! electron |! configurations. |! F |! = |! 1s |! 2 |! 2s22p5 |! so |! the |! most |! likely |! ion |! to |! form |! would |! have |! a |! filled |! valence |! shell, |! which |! means |! F |! would |! add |! (acquire) |! one |! electron, |! making |! it |! F |! - |!.
How |! are |! ionic |! compounds |! different |! from |! covalent |! compounds? |! - |! Correct |! answer |! ✔Ionic |! compounds: metal |! with |! a |! nonmetal electrons |! are |! not |! shared |! in |! bonds the |! metal |! will |! have |! a |! + |! charge |! and |! the |! nonmetal |! will |! have |! a |! - |! charge Covalent |! compounds: nonmetals |! with |! nonmetals electrons |! are |! shared |! in |! bonds there |! may |! be |! partial |! charges |! from |! polar |! bonds What |! would |! be |! the |! formula |! of |! calcium |! fluoride? |! - |! Correct |! answer |! ✔CaF Explanation: Ca |! has |! a |! +2 |! charge. |! F |! has |! a |! -1 |! charge. |! So |! there |! must |! be |! 2 |! F |! per |! 1 |! Ca. In |! ionic |! compounds |! we |! always |! put |! the |! _______ |! first |! - |! Correct |! answer |! ✔Metal What |! do |! you |! think |! influences |! different |! properties |! of |! ionic |! compounds? |! What |! would |! change |! the |! melting |! temperature? |! What |! would |! impact |! the |! solubility? |! - |! Correct |! answer |! ✔Ion |! charge |! should |! be |! an |! obvious |! one. |! What |! would |! be |! another? |! Have |! you |! ever |! heard |! of |! Coulomb's |! law? What |! would |! be |! the |! formula |! of |! aluminum |! sulfide? |! - |! Correct |! answer |! ✔Al2S Explanation:
You |! treat |! the |! polyatomic |! ion |! like |! a |! "package". |! You |! don't |! separate |! it. |! If |! there |! are |! two |! of |! them, |! you |! put |! parentheses |! around |! the |! "package" |! and |! a |! subscript |! to |! balance |! charges. What |! would |! be |! the |! formula |! of |! sodium |! phosphate? |! - |! Correct |! answer |! ✔Na |! 3 |! PO |! 4 What |! would |! be |! the |! formula |! of |! sodium |! sulfate? |! - |! Correct |! answer |! ✔Na |! 2 |! SO |! 4 What |! would |! be |! the |! formula |! of |! ammonium |! chloride? |! - |! Correct |! answer |! ✔NH4Cl Conductivity |! (for |! ionic |! compounds) |! - |! Correct |! answer |! ✔movement |! of |! electrons |! (electrons |! and |! ions) In |! a |! solid |! state |! they |! cant |! move In |! a |! liquid |! state |! they |! can |! move |! and |! can |! then |! conduct _________(______) |! are |! localized |! on |! the |! ion |! and |! cannot |! flow |! - |! Correct |! answer |! ✔Charges |! (electrons) In |! a |! ______ |! _______, |! the |! ions |! can |! move |! freely |! and |! establish |! an |! electric |! current |! - |! Correct |! answer |! ✔Molten |! state Coulumb's |! Law |! - |! Correct |! answer |! ✔F=(qcation |! x |! qanion) |! /r^ q= |! charges
f= |! force |! of |! attraction r= |! size Losing |! electrons |! for |! ions |! it |! essentially |! looses |! a |! ______ |! so |! it |! substantially |! _________ |! - |! Correct |! answer |! ✔Shell, |! smaller The |! r |! (the |! size) |! variable |! increases |! how |! on |! the |! periodic |! table? |! - |! Correct |! answer |! ✔Increases |! left |! to |! right, |! and |! up |! to |! down Ionic |! compounds |! tend |! to |! have |! ____ |! melting |! points |! and |! _____ |! boiling |! points |! because |! _____ |! - |! Correct |! answer |! ✔Tend |! to |! have |! high |! melting |! and |! boiling |! points Stronger |! than |! bonds |! and |! IMFs Order |! ionic |! compounds |! in |! increasing |! melting |! point: NaCl, |! NaBr, |! NaF CaO, |! NaCl, |! MgO |! - |! Correct |! answer |! ✔NaBr, |! NaCl, |! NaF NaCl, |! CaO, |! MgO As |! you |! increase |! _ |! or |! decrease |! ______= |! increasing |! intermolecular |! forces |! and |! increase |! melting |! point |! - |! Correct |! answer |! ✔q, |! size
In |! particular, |! ionic |! compounds |! are |! made |! up |! of |! ions |! arranged |! into |! ____________ |! networks |! and |! not |! by |! atoms |! covalently |! bonded |! as |! independent |! molecules. |! - |! Correct |! answer |! ✔Crystalline MgO |! is |! wat |! type |! of |! cation |! an |! anion |! - |! Correct |! answer |! ✔It |! is |! an |! monoatomic |! cations |! and |! anions The |! electronegativities |! of |! metallic |! elements |! tend |! to |! be |! ___, |! while |! nonmetallic |! elements |! have |! the |! _______ |! electronegativities |! in |! the |! periodic |! table |! - |! Correct |! answer |! ✔Low, |! higher How |! the |! valence |! electrons |! actually |! redistribute |! between |! the |! two |! interacting |! particles |! depends |! on |! the |! value |! of |! both |! the |! _________ |! in |! electronegativities |! △χ=χA−χB |! and |! the |! ____________ |! electronegativity |! χAv=(χA+χB)/2 |! of |! the |! atoms |! involved. |! - |! Correct |! answer |! ✔Difference, |! average In |! which |! types |! of |! atoms, |! magnesium |! or |! oxygen, |! do |! valence |! electrons |! occupy |! lower |! potential |! energy |! states? |! - |! Correct |! answer |! ✔Oxygen What |! charge |! are |! oxygen |! (O) |! atoms |! likely |! to |! acquire |! when |! interacting |! with |! magnesium |! (Mg) |! atoms? |! - |! Correct |! answer |! ✔- We |! can |! expect |! atoms |! of |! ________________ |! elements |! to |! acquire |! a |! negative |! charge |! equal |! in |! magnitude |! to |! the |! number |! of |! electrons |! they |! can |! accept |! in |! the |! unoccupied |! orbitals |! in |! their |! valence |! shell. |! - |! Correct |! answer |! ✔Nonmetallic
Accepting |! more |! electrons |! into |! higher |! energy |! states |! would |! have |! too |! high |! an |! energy |! cost. |! The |! resulting |! anions |! will |! then |! have |! an |! electron |! configuration |! similar |! to |! that |! of |! the |! nearest |! ____ |! ___ |! element |! in |! the |! same |! period |! in |! the |! periodic |! table |! - |! Correct |! answer |! ✔Noble |! gas ______ |! electrons |! are |! not |! transferred |! during |! these |! interactions |! as |! they |! occupy |! rather |! low |! energy |! states |! in |! atoms |! of |! metallic |! elements. |! - |! Correct |! answer |! ✔Core Metallic |! elements |! in |! Group |! 13 |! of |! the |! periodic |! table |! (e.g., |! Al, |! Ga, |! In) |! tend |! to |! form |! stable |! cations |! with |! one |! of |! two |! possible |! positive |! charges |! when |! reacting |! with |! nonmetallic |! elements. |! What |! are |! the |! two |! electric |! charges |! that |! these |! types |! of |! ions |! are |! likely |! to |! acquire? |! - |! Correct |! answer |! ✔+ No |! matter |! what |! ions |! are |! formed |! during |! the |! reaction |! of |! metallic |! and |! nonmetallic |! elements, |! the |! ionic |! network |! that |! is |! formed |! has |! __ |! net |! charge |! - |! Correct |! answer |! ✔No Predict |! the |! formula |! unit |! of |! the |! ionic |! compounds |! that |! result |! from |! the |! combination |! of |! the |! following |! elemental |! substances: |! Na(s) |! + |! O2(g) |! (Hint: |! During |! the |! reaction, |! each |! substance |! will |! generate |! stable |! monoatomic |! ions |! with |! a |! charge |! that |! can |! be |! predicted |! by |! analyzing |! the |! number |! of |! valence |! electrons |! present |! in |! the |! neutral |! atoms.) |! - |! Correct |! answer |! ✔Na2O Predict |! the |! formula |! unit |! of |! the |! ionic |! compounds |! that |! result |! from |! the |! combination |! of |! the |! following |! elemental |! substances: |! K(s) |! + |! F2(g) |! (Hint: |! During |! the |! reaction, |! each |! substance |! will |! generate |! stable |! monoatomic |! ions |! with |! a |!
Many |! physical |! properties |! of |! ionic |! compounds |! are |! determined |! by |! the |! _______ |! and |! the |! ____ |! of |! the |! ions |! in |! the |! network |! - |! Correct |! answer |! ✔Charge, |! size ______ |! and |! _______ |! factors |! influence |! the |! magnitude |! of |! the |! repulsive |! and |! attractive |! electrostatic |! forces |! between |! particles |! in |! the |! system |! - |! Correct |! answer |! ✔Charge, |! size Attractive |! interactions |! between |! anions |! and |! cations |! tend |! to |! be |! pretty |! _________; |! separating |! these |! charged |! particles |! typically |! requires |! energy |! investments |! between |! 400 |! and |! 4000 |! kJ/mol |! - |! Correct |! answer |! ✔Strong Repulsion |! between |! ions |! of |! the |! same |! charge |! are |! ________ |! - |! Correct |! answer |! ✔Strong The |! presence |! of |! impurities |! in |! the |! crystal |! lattice |! of |! an |! ionic |! compound |! or |! the |! application |! of |! a |! force |! that |! deforms |! the |! crystalline |! network |! may |! force |! equally |! charged |! ions |! close |! together, |! ____________ |! the |! solid |! structure |! - |! Correct |! answer |! ✔Destabilizing Coulomb's |! Law |! - |! Correct |! answer |! ✔F=K |! q₁*q₂/r², |! magnitude |! of |! force |! between |! two |! charges Coulomb's |! constant |! K |! is |! equal |! to |! - |! Correct |! answer |! ✔8.988 |! x |! 10^9 |! Nm^2/C^2 |! when |! expressed |! in |! SI |! units
According |! to |! this |! relationship, |! the |! higher |! the |! ion |! charges |! and |! the |! ______ |! the |! ion |! sizes, |! the |! _______ |! the |! electrostatic |! force |! between |! particles |! - |! Correct |! answer |! ✔Smaller, |! larger ________; |! losing |! valence |! electrons |! results |! in |! positive |! ions |! with |! a |! ______ |! radius |! as |! the |! lost |! electrons |! are |! taken |! from |! the |! most |! external |! orbitals. |! Additionally, |! the |! net |! repulsion |! force |! on |! the |! remaining |! electrons |! _______, |! facilitating |! their |! getting |! closer |! to |! the |! atomic |! nucleus. |! - |! Correct |! answer |! ✔Cations, |! smaller, |! decreases ______; |! on |! the |! other |! hand, |! gaining |! electrons |! results |! in |! negatively |! charged |! ions |! with |! a |! _______ |! radius; |! the |! additional |! electrons |! are |! located |! in |! outer |! orbitals |! and |! the |! net |! repulsion |! between |! electrons |! in |! the |! system |! ___________. |! - |! Correct |! answer |! ✔Anions, |! larger, |! increases For |! particles |! with |! electric |! charges |! of |! the |! same |! type, |! either |! positive |! or |! negative, |! ion |! size |! increases |! as |! we |! move |! from |! ____ |! __ |! _____ |! within |! a |! period |! and |! from |! ___ |! __ |! _______ |! within |! a |! group |! in |! the |! periodic |! table |! - |! Correct |! answer |! ✔Right |! to |! left, |! top |! to |! bottom Based |! on |! a |! comparative |! analysis |! of |! the |! charge |! and |! size |! of |! the |! ions |! that |! make |! up |! the |! ionic |! compounds |! in |! each |! of |! the |! following |! sets |! of |! substances, |! arrange |! then |! from |! higher |! (top) |! to |! lower |! (bottom) |! melting |! points: |! NaCl, |! NaF, |! NaBr |! - |! Correct |! answer |! ✔NaF, |! NaCl, |! NaBr Based |! on |! a |! comparative |! analysis |! of |! the |! charge |! and |! size |! of |! the |! ions |! that |! make |! up |! the |! ionic |! compounds |! in |! each |! of |! the |! following |! sets |! of |! substances, |! arrange |!
If |! ions |! interact |! ______ |! with |! each |! other |! and |! more |! strongly |! with |! water |! molecules |! they |! may |! separate. |! - |! Correct |! answer |! ✔Weakly Strong |! interactions |! between |! ions |! and |! water |! molecules |! may |! ________ |! the |! number |! of |! configurations |! that |! such |! molecules |! can |! adopt, |! reducing |! the |! likelihood |! that |! _________ |! ________ |! will |! lead |! to |! the |! dissolution |! of |! the |! ionic |! solid |! - |! Correct |! answer |! ✔Reduce, |! random |! motion What |! should |! happen |! to |! the |! solubility |! of |! ionic |! compound |! when |! the |! ion |! charge |! increases? |! - |! Correct |! answer |! ✔Decrease For |! an |! ionic |! compound |! to |! be |! soluble |! in |! water, |! at |! least |! one |! of |! the |! following |! conditions |! needs |! to |! be |! met: |! - |! Correct |! answer |! ✔1) |! The |! net |! interactions |! between |! ions |! and |! water |! molecules |! should |! be |! stronger |! than |! the |! net |! interactions |! between |! the |! ions |! themselves. |! Thus, |! the |! dissolution |! process |! results |! in |! a |! state |! with |! a |! lower |! potential |! energy.
- |! The |! number |! of |! configurations |! that |! the |! ions |! and |! the |! water |! molecules |! can |! adopt |! when |! mixed |! is |! larger |! than |! the |! total |! number |! of |! configurations |! that |! they |! can |! have |! if |! they |! do |! not |! mix. |! Under |! these |! conditions, |! random |! particle |! motions |! are |! likely |! to |! result |! in |! dissolution. For |! solubility |! of |! ionic |! compounds |! in |! water |! if |! both |! of |! these |! conditions |! are |! satisfied, |! the |! ionic |! compound |! is |! likely |! to |! be |! soluble |! at |! ___ |! temperatures. |! If |! only |! one |! of |! these |! conditions |! is |! met, |! the |! outcome |! will |! depend |! on |! which |! competing |! factors |! (i.e., |! strength |! of |! interactions |! versus |! number |! of |! configurations) |! is |! dominant. |! In |! these |! cases, |! the |! solubility |! of |! the |! ionic |!
compound |! is |! likely |! to |! ____ |! significantly |! with |! temperature. |! - |! Correct |! answer |! ✔All, |! vary For |! solubility |! of |! ionic |! compounds |! in |! water |! finally, |! if |! none |! of |! these |! conditions |! are |! satisfied, |! the |! ionic |! compound |! will |! be |! rather |! ________. |! - |! Correct |! answer |! ✔Insoluble In |! general, |! conditions |! that |! favor |! the |! solubility |! of |! ionic |! compounds |! tend |! to |! be |! dominant |! when |! these |! substances |! are |! made |! up |! of |! ions |! with |! _________ |! electric |! charges. |! This |! is |! mostly |! because |! ions |! with |! ______ |! charges |! do |! not |! strongly |! __________ |! the |! configurations |! that |! surrounding |! water |! molecules |! can |! adopt, |! facilitating |! the |! dissolution |! process |! - |! Correct |! answer |! ✔Small, |! small, |! constrain The |! larger |! the |! charge |! of |! the |! ions, |! the |! larger |! the |! ___-_______ |! interactions, |! and |! the |! larger |! the |! probability |! that |! molecular |! movements |! will |! be |! ____________ |! in |! the |! vicinity |! of |! those |! ions. |! The |! lower |! the |! number |! of |! configurations |! that |! water |! molecules |! can |! adopt, |! the |! lower |! the |! likelihood |! that |! _______ |! _________ |! will |! lead |! to |! the |! formation |! of |! such |! a |! state. |! - |! Correct |! answer |! ✔Ion-dipole, |! constrained, |! random |! motions Based |! on |! the |! examples |! provided, |! predict |! whether |! the |! following |! ionic |! compounds |! will |! be |! soluble |! in |! water: KCl: CaS: |! MgCl2: AlN: |! - |! Correct |! answer |! ✔Soluble Insoluble
KCl, |! MgCl2, |! MgS CaCl2, |! KCl, |! NaCl |! - |! Correct |! answer |! ✔ __: |! Shows |! the |! relative |! strength |! of |! ion-ion |! (UD) |! and |! ion-water |! (D) |! interactions |! - |! Correct |! answer |! ✔PE __: |! shows |! the |! amount |! of |! ordering |! the |! ions |! have |! ion |! water |! (ion-water |! interactions |! are |! strong) |! - |! Correct |! answer |! ✔#C Assumptions:
|! - |! Correct |! answer |! ✔1. |! Chemical |! reactions |! require |! a |! rearrangement |! of |! atoms |! to |! form |! something |! new |! and |! different.
|! Reactions |! either |! produce |! energy |! (exo, |! ∆H= |! −) |! or |! require |! energy |! (endo, |! ∆H |! = |! +).
|! For |! a |! reaction |! to |! happen, |! particles |! must |! collide.
|! Particles |! must |! collide |! with |! proper |! orientation.
|! Particles |! must |! collide |! with |! some |! threshold |! energy |! (activation |! energy, |! Ea).
|! Both |! forward |! and |! reverse |! reactions |! are |! occurring |! when |! a |! reaction |! reaches |! equilibrium |! (appears |! to |! "stop").
Balance |! the |! following |! chemical |! reactions: Fe(s) |! + |! O2(g)Fe2O3(s) Fe2O3(s) |! + |! C(s)Fe(s) |! + |! CO2(g) C2H6O(l) |! + |! O2(g)H2O(g) |! + |! CO2(g) H2(g) |! + |! NO(g)N2(g) |! + |! H2O(g) |! - |! Correct |! answer |! ✔ For |! a |! reaction |! to |! happen, |! particles |! must |! __________. |! - |! Correct |! answer |! ✔Collide Anything |! that |! increases |! the |! # |! of |! __________, |! will |! increase |! the |! rate |! (↑T |! ↑P |! ↑concentration |! ↓volume) |! - |! Correct |! answer |! ✔Collisions Particles |! must |! collide |! with |! proper |! ___________. |! - |! Correct |! answer |! ✔Orientation Collision |! efficiency |! improves |! with |! __________(s |! and |! fewer |! particles, |! and |! simpler |! particles) |! - |! Correct |! answer |! ✔Proximity Particles |! must |! collide |! with |! some |! threshold |! __________ |! (activation |! energy, Ea). |! ↓Ea |! ↑rate |! - |! Correct |! answer |! ✔Energy Catalysts: |! - |! Correct |! answer |! ✔Substance |! that |! increases |! the |! rate |! of |! the |! reaction |! by |! decreasing |! Ea, |! but |! does |! not |! change |! the |! PE |! of |! R |! or |! P
- |! reverse |! reaction |! (formation |! of |! reactants) |! is |! favored |! by |! both |! CE |! and |! Ea 1 |! and |! 2 |! are |! Always |! R-favored |! or |! P-favored
- |! forward |! reaction |! is |! favored |! by |! CE |! and |! reverse |! is |! favored |! by |! Ea
- |! reverse |! reaction |! is |! favored |! by |! CE |! and |! forward |! reaction |! is |! favored |! by |! Ea |! 3 |! and |! 4 |! are |! favorability |! will |! be |! temperature |! dependent
