Chemistry Midterm Review Part 2

Chemistry Midterm Review Part 2

Multiple Choice

[2.a-b]

When do substances with ionic bonds NOT conduct electricity?

• when solid

• when melted (molten)

• when dissolved in water

Multiple Choice

[2.a] Which of the following forces is the strongest, and which is the weakest?

London Dispersion

Dipole-dipole

Hydrogen bond

Covalent molecules

Ionic

Metallic

• Strongest: Metallic

  Weakest: London Dispersion

• Strongest: London Dispersion

  Weakest: Metallic

• Strongest: Hydrogen bond

  Weakest: Ionic bond

Multiple Choice

[2.a-b]

(1) NH₃ has a lower boiling point than BaI₂.

(2) NH₃ (nonmetal + nonmetal) is an ionic compound, and BaI₂ (metal + nonmental) is a covalent compound.

(3) Statement (2) is the REASON WHY statement (1) is true.

• (1) True

  (2) True

  (3) True

• (1) True

  (2) False

  (3) False

• (1) False

  (2) True

  (3) False

Multiple Choice

[2.a]

Which of the following is NOT able to form Hydrogen bonds?

• CH₃Br

• CH₃OH

• NH₃

• HF

Multiple Choice

[2.a-b]

Which of the following would have the highest boiling point?

Multiple Choice

[2.b]

The physical properties of an unknown compound were measured:

Melting Point = –96 ^oC

Boiling Point = 68 ^oC

The compound COULD be:

• Propane:

  MP = –188 ^oC

  BP = –43 ^oC

• Hexane:

  MP = –95.5 ^oC

  BP = 69 ^oC

• Octane:

  MP = –57 ^oC

  BP = 125 ^oC

Multiple Choice

[2.a-b]

Atoms of the noble gases (He, Ne, Ar, Xe, Kr, Rn) exist by themselves (monatomic), but you always see the diatomic form of H₂, N₂, O₂, F₂, Cl₂, Br₂ and I₂ because these elements are too reactive to exist by themselves.

• True

• False

Multiple Choice

[2.a-c]

The "Free Electron Theory of Metals" (= "sea of electrons" model) explains why metals

• conduct electricity and are malleable

• rust easily

• are soft and break apart

Multiple Choice

[2.c]

Three engineering materials are shown. Which of the following would be ideal to make the plastic bags for Walmart?

Multiple Choice

[3.a]

Which equation violates the Law of Conservation of Matter?

A) S (s) + 6 F₂ (g) ➝ SF₆ (g)

B) 2 Cs (s) + 2 H₂O (l) ➝ 2 CsOH (aq) + H₂ (g)

(Use scratch paper if necessary)

• A

• B

Multiple Choice

[3.a]

Which option has the equations matched correctly?

• Synthesis: A + B --> AB

  Decomposition: AB --> A + B

  Single Replacement: A + BC --> AC + B

  Double Replacement: AB + CD --> AD + BC

• Synthesis: AB --> A + B

  Decomposition: A + B --> AB

  Single Replacement: A + BC --> AC + B

  Double Replacement: AB + CD --> AD + BC

Multiple Choice

[3.a]

2HBr --> H₂ + Br₂

This equation models which type of reaction?

• Synthesis

  
  

  A + B --> AB

• Decomposition

  
  

  AB --> A + B

• Single Replacement

  
  

  A + BC --> AC + B

• Double Replacement

  
  

  AB + CD --> AD + CB

Multiple Choice

[3.b]

You plan to add manganese(IV) oxide, MnO₂, to hydrochloric acid, HCl and model your reaction with the equation

MnO₂(s) + 4 HCl(aq) --> MnCl₂(aq) + Cl₂(g) + 2 H₂O(l)

According to your equation, what do you expect to observe as EVIDENCE of a chemical change?

• color change

• precipitate formation

• gas production

Multiple Choice

[3.c]

On a Star Wars planet, there are different elements:

Cz (molar mass = 1 ^g/_mol)

Y (molar mass = 3 ^g/_mol)

Ox (molar mass = 4 ^g/_mol)

What is the molar mass of Cz₂(YOx₂)₃? Show your work!

• 19 ^g/_mol

• 29 ^g/_mol

• 35 ^g/_mol

Multiple Choice

[3.c]

What is the percent composition by mass of sulfur in sodium sulfide (Na₂S)?

(Hint: Molar mass of Na = 23 ^g/_mol AND Molar mass of S = 32 ^g/_mol)

Show your work!

• 33%

• 41%

• 58%