General Chemistry

Question 1

How many protons, neutrons, and electrons are in the following?

1. ²⁴₁₂MG
2. ⁶³₂₉Cu²⁺
3. ³⁵₁₇Cl^-
4. What are Valence Electrons?

Answer 1

1. 12 P, 12 N, and 12 e-
2. 29 P, 34 N, and 27 e^-
3. 17 P, 18 N, and 18 e^-
4. The electrons farthest from the nucleus, as well as any electrons available for boding, are the valence electrons

Question 2

1. What is ionization energy (IE)?
2. What is the ionization energy trend within the periodic table?
3. Compare the values of the firs ionization and second ionization energy of an atom.
4. What is electron affinity?

Answer 2

1. Ionization energy is the energy required to completelt remove an electron from an atom.
2. IE increases as you move from left to right across a period and up a group
3. The second ionization energy is always higher than the first ionization energy of an atom
4. Electron affinity is the energy released when an atom accepts an electron

Question 3

1. What is the electron affinity trend within the periodic table?
2. (T/F) Group VIIIA elements have high electron affinities
3. What is electronegativity
4. What is the electronegative trend within the periodic table?

Answer 3

1. Electron affinity increases as you move from left to right across a period and up a group
2. False, Group VIIIA elements have a stable octet and have an electron affinity approaching zero
3. Electronegativity is a measure of the attraction an atom has for electrons in a chemical bond
4. Electronegativity increases as you move from left to right across a period and up a group

Question 4

Draw the Lewis structure for HCN

Answer 4

The Lewis structure for HCN is the following:

H-C_=_N:

Question 5

1. What is an elementary reaction?
2. (T/F) A complex reaction can be broken down into two or more elementary reactions
3. What is an intermediate?
4. What is the rate-determining step of a reaction?

Answer 5

1. An elementary reaction is a reaction that cannot be decomposed into other reactions
2. True
3. An intermediate is a complex that appears during the course of a reaction but does not appear in the net reaction, or as a final product
4. The rate determining step is the slowest step of a reaction

Question 6

1. If there is much more product than reactant at equilibrium, what can be said of Keq (as compared to 1)?
2. If Keq is very small comparedto 1, then what canbe said about the amount of reactants and products at equilibrium?
3. According to Le Chatelier’s Principle, in which direction will equilibrium shift if products are removed?

Answer 6

1. Keq would be greater than 1
2. If Keq is led than 1, there will be more reactants than products at equilibrium
3. If products are removed, equilibrium will shift to favor the forward reaction

Question 7

1. When does a system reach maximum entropy?
2. What is Gibb’s Free Energy equation? ΔG =
3. How does the value of ΔG correlate with the spontaneity of a reaction?

Answer 7

1. Maximum entropy occurs when a system is at equilibrium
2. ΔG = ΔH – T ΔS
3. ΔG is negative for a spontaneous reaction. ΔG is positive for a non-spontaneous reaction

Question 8

1. What are the two most common types of crystalline
2. (T/F) A unit cell is a repeating unit of crystals
3. What is condensation? Evaporation?

Answer 8

1. The two common types of crystalline solids are ionic and metallic
2. True
3. Condensation occurs when gas changes to liquid. Evaporation occurs when liquid changes to gas

Question 9

Fe(OH)³ (s) ⇔ Fe³⁺ (aq) + 3OH^- (aq)

1. What is the ion product (I.P.) for the above reaction?
2. What is the solubility product constant (K_sp) for the above reaction?
3. What is the difference between I.P. and K_sp?

Answer 9

1. I.P. = [Fe³⁺][OH^-]_sat³
   2 K_sp= [Fe³⁺]_sat[OH^-]_sat³
2. I.P. is defined with respect to initial concentrations. K_sp is defined with respect to the concentrations of saturated solution at equilibrium

Question 10

1. (True/False) When adding standard potentials, multiple by the number of moles oxidized or reduced first.
2. What is the formula for the standard free energy of an electrochemical cell? ΔG^o =
3. What is the relationship between EMF and K_eq?

Answer 10

1. False, never multiply by the number of moles when adding standard potentials.
2. ΔG^o = -(number of moles)(Faraday’s constant)(EMF)= -nFE
3. nFE = RT lnK_eq