Final Exam CHEM 2 questions with
answers
1. The speed of a wave (c) is the product of its frequency (ν) and
wavelength (λ).: E = hv = h x c / λ
2. nm to
m or
m to nm: 1 m / 10^9 nm
or
10^9 nm / 1 m
3. What is the maximum number of electrons that can have the
quantum num- bers n = 3, ℓ = 2, mℓ = -2?: The Pauli exclusion principle states that
no two electrons in a given atom can share the same set of four quantum numbers (n, ℓ, mℓ, ms).
This set of quantum numbers contains three quantum numbers, with the only missing quantum
number being ms, which can take on the values +½ and -½. Therefore, this set of three quantum
numbers represents a single atomic orbital, which can contain two unique electrons: one with ms
= +½ and one with ms = -½.
4. An exothermic reaction causes the surroundings to: An exothermic
reaction transfers energy from the system to the surroundings. That tells us the surroundings
will get warmer.
5. A theory is another word for
a(n) .: A theory or model is a well established
explanation of a phenomenon based on a series of facts and a body of evidence.
6. What is the definition of a natural law?: A scientific law summarizes an observab
behavior.
7. The skeletal structure of a complex organic molecule is shown below.
Deter- mine the number of sigma (σ) and pi (π) bonds in the molecule.:
Remember a single bond = 1 σ; a double bond = 1 σ + 1 π; a triple bond = 1 σ + 2 π. This
molecule contains 6 double bonds, so there are 6σ and 6π. There are 28 single bonds, so there are 28 σ.
This is a total 34σ and 6π.
8. strontium phosphate: Sr₃(PO₄)₂
,9. Which of the following statements is true?: One driving force in the
vaporization of a liquid is an increase in disorder (entropy). Gas molecules are more disordered
than liquid molecules. Adding a non-volatile solute to a liquid also increases the disorder of the liquid
molecules, so the ditterence in disorder between the liquid and gas phases is not as great as with a
pure substance. Therefore the tendency to vaporize is not as great for the solution as it is for the pure
liquid, resulting in a lower vapor pressure for the solution.
10. Which of the following aqueous solutions would have the
highest boiling point?
A) 1.0 m NaNO3
, B) 1.0 m HF
C) 1.0 m C₆H₁₂O₆
D) 1.0 m CaCl2: The dissolved solute will raise the boiling point. The more "things" that are
dissolved (ions or molecules), the higher the boiling point will be. The CaCl₂ will break up into one Ca²⁺
ion and two Cl⁻ ions and there will be a concentration of 3.0 m of "things" in solution. The other choices
will have fewer "things" in solution and will raise the boiling point less.
11. Which one of the following aqueous solutions would have the
highest freez- ing point?
A) 1.0 m NaNO3
B) 2.0 m CH3OH
C) 1.0 m C₆H₁₂O₆
D) 1.0 m CaCl2: The dissolved solute will lower the freezing point. The more "things" that are
dissolved (ions or molecules), the lower the freezing point will be. Since C₆H₁₂O₆ is a molecule, it will
not break apart and there will only be a concentration of 1.0 m of molecules in solution. It will lower
the freezing point less than all the other choices. There will be fewer "things" in solution and this will
lower the freezing point less than the other choices.
12. isoelectronic ions: ions containing the same number of electrons
13. Which of the following bonds is the most polar?: Elements that are
located far away from each other on the periodic table have larger electronegativity ditterences and
therefore make more polar bonds. Of all the element pairs listed, Rb and Br are the farthest apart.
14. Three blocks of the same shape and size are placed in front of
you. Block A has a mass of 3.0 g, block B is 5.0 g, and block C is 10.0 g.
Which has the higher density?: Density is the ratio of mass to volume. Since the volume is
constant between all the blocks, then the block with the highest mass will have the highest density.
15. Density equation:
mass/volume dRT = PM
answers
1. The speed of a wave (c) is the product of its frequency (ν) and
wavelength (λ).: E = hv = h x c / λ
2. nm to
m or
m to nm: 1 m / 10^9 nm
or
10^9 nm / 1 m
3. What is the maximum number of electrons that can have the
quantum num- bers n = 3, ℓ = 2, mℓ = -2?: The Pauli exclusion principle states that
no two electrons in a given atom can share the same set of four quantum numbers (n, ℓ, mℓ, ms).
This set of quantum numbers contains three quantum numbers, with the only missing quantum
number being ms, which can take on the values +½ and -½. Therefore, this set of three quantum
numbers represents a single atomic orbital, which can contain two unique electrons: one with ms
= +½ and one with ms = -½.
4. An exothermic reaction causes the surroundings to: An exothermic
reaction transfers energy from the system to the surroundings. That tells us the surroundings
will get warmer.
5. A theory is another word for
a(n) .: A theory or model is a well established
explanation of a phenomenon based on a series of facts and a body of evidence.
6. What is the definition of a natural law?: A scientific law summarizes an observab
behavior.
7. The skeletal structure of a complex organic molecule is shown below.
Deter- mine the number of sigma (σ) and pi (π) bonds in the molecule.:
Remember a single bond = 1 σ; a double bond = 1 σ + 1 π; a triple bond = 1 σ + 2 π. This
molecule contains 6 double bonds, so there are 6σ and 6π. There are 28 single bonds, so there are 28 σ.
This is a total 34σ and 6π.
8. strontium phosphate: Sr₃(PO₄)₂
,9. Which of the following statements is true?: One driving force in the
vaporization of a liquid is an increase in disorder (entropy). Gas molecules are more disordered
than liquid molecules. Adding a non-volatile solute to a liquid also increases the disorder of the liquid
molecules, so the ditterence in disorder between the liquid and gas phases is not as great as with a
pure substance. Therefore the tendency to vaporize is not as great for the solution as it is for the pure
liquid, resulting in a lower vapor pressure for the solution.
10. Which of the following aqueous solutions would have the
highest boiling point?
A) 1.0 m NaNO3
, B) 1.0 m HF
C) 1.0 m C₆H₁₂O₆
D) 1.0 m CaCl2: The dissolved solute will raise the boiling point. The more "things" that are
dissolved (ions or molecules), the higher the boiling point will be. The CaCl₂ will break up into one Ca²⁺
ion and two Cl⁻ ions and there will be a concentration of 3.0 m of "things" in solution. The other choices
will have fewer "things" in solution and will raise the boiling point less.
11. Which one of the following aqueous solutions would have the
highest freez- ing point?
A) 1.0 m NaNO3
B) 2.0 m CH3OH
C) 1.0 m C₆H₁₂O₆
D) 1.0 m CaCl2: The dissolved solute will lower the freezing point. The more "things" that are
dissolved (ions or molecules), the lower the freezing point will be. Since C₆H₁₂O₆ is a molecule, it will
not break apart and there will only be a concentration of 1.0 m of molecules in solution. It will lower
the freezing point less than all the other choices. There will be fewer "things" in solution and this will
lower the freezing point less than the other choices.
12. isoelectronic ions: ions containing the same number of electrons
13. Which of the following bonds is the most polar?: Elements that are
located far away from each other on the periodic table have larger electronegativity ditterences and
therefore make more polar bonds. Of all the element pairs listed, Rb and Br are the farthest apart.
14. Three blocks of the same shape and size are placed in front of
you. Block A has a mass of 3.0 g, block B is 5.0 g, and block C is 10.0 g.
Which has the higher density?: Density is the ratio of mass to volume. Since the volume is
constant between all the blocks, then the block with the highest mass will have the highest density.
15. Density equation:
mass/volume dRT = PM
