Bonding and IPFs
How many lone pairs are on the central atom of BrF3?
What is 2 lone pairs
Explanation: this molecule has 28 valence electrons, Br has 7, with three single bonds, leaving 2 lone pairs
What is the electron configuration for a sodium ion in its ground state?
What is 1s2 2s2 2p6
Explanation: the ground state for the sodium ION, it has lost its s1 electron
What is the equilibrium expression for the reaction, NiO(s) + H2(g) == Ni(s) + H2O(g)?
What is Keq = [H2O]/[H2]
What is the [OH-] of a solution with a pH of 5?
What is 1 x 10-9
Explanation: pH + pOH = 14, pOH = 9, reverse of -log = 1 x 10-pOH
For the rate law, rate = k[A]2, how could you plot a straight line?
What is 1/[A]
Explanation: the rate law is second order, so a straight line could be graphed as 1/[A]
What is the hybridization for the oxygen atom in CH3OH?
What is sp3
Explanation: this oxygen atom in this molecule has four domains (two single bonds and two lone pairs)
Which of the following has the smallest ionic radius?:
O2-
F-
Na+
Mg2+
Al3+
What is Al3+
Explanation: Al has the most protons and the largest nuclear charge, forcing the electron cloud to shrink
2CO(g) + O2(g) == 2CO2(g)
Given the following data, what is the K for the reaction above?
C + 1/2O2 == CO K1 = 5
C + O2 == CO2 K2 = 1
What is 0.04
Explanation: 1/(5)2 x (1)2 = 1/25 = 0.04
Which species in H2PO4- + H2O -- H3O+ HPO42- behave as bases?
What is H2O and HPO42-
Explanation: bases always gain an H+ In the reaction
For the reaction 2NO2 + F2 -- 2NO2F, the following mechanism is given:
Step one: NO2 + F2 -- NO2F + F (Slow)
Step two: F + NO2 -- NO2F (Fast)
Which of the following are correct?
1. rate law = k[NO2]2[F2]
2. F is an intermediate
3. the reaction is first order with respect to F2
What is 2 and 3
Explanation: the rate law can be defined as the reactants of the slow step, and it is first order with respect to NO2 and F2. F is also product in one step and is used in the other making it an intermediate.
What is the molecular geometry of BrF5?
What is square pyramid
Explanation: six domains with one lone pair on the central atom
Which of the following sets contains species that are
isoelectronic?
1. Br, Kr, Rb
2. O2-, S2-, Se2-
3. Al3-, S2-, Ar
4. Cl+, Ar, K-
5. F-, Ne, Na+
What is 5. F-, Ne, Na+
Explanation: all of the species in 5 have 10 electrons, isoelectronic means they have the same number of electrons.
When the temperature of the equilibrium system, N2(g) + 3H2(g) ⇆ 2NH3(g) + 92 kJ, is increased at a constant volume, which of the following will be least affected?
1. mass
2. pressure
3. concentration of NH3(g)
4.concentration of N2(g)
5. average kinetic energy
What is 1. mass
Explanation: Increase in temperature will make the exothermic reaction shift left, however all of the atoms are still in the system, so, the mass will not change
Ka of HClO = 3.0 x 10-8 at 25.0oC. What is the pH of a 0.030 M solution of HClO?
What is 4.52
Explanation: x2 problem, 3.0 x 10-8 = x2/0.030M
131I has a half life of 3.5 days, assuming you start with an 8.0g sample, what mass will remain after 2 weeks?
What is 0.5g
Explanation: there are 4 half lives over the course of 2 weeks
Which of the following has the lowest boiling point?
H2O
H2S
H2Te
H2Se
What is H2S
Explanation: H2O has hydrogen bonding (strong IMF), H2Te and H2Se are bigger than H2S so they have stronger LDF's
which of the following is the correct ordering of atoms in progressively decreasing ionization energy
1. F > O > C > Li > Na
2. Na > Li > C > O > F
3. F > O > C > Na > Li
4. C > O > F > Li > Na
5. O > F > C > Na > Li
What is 1
Explanation: ionization is inversely proportional to size (N is an exception to this rule)
What is the solubility of lead(II) fluoride,
Ksp = 4.0 × 10−8, in a 0.0040 M lead(II) nitrate solution?
What is (1.0 x 10-5)1/2/2 M
Explanation: Ksp = (0.004)[2s]2 = 4.0 × 10-8
s = (1.0 x 10-5)1/2/2 M
What is the pH of the solution made by combining 100.0ml of 0.28 M HC2H3O2 and 50.0ml of 0.36 M NaOH? (Ka of HC2H3O2 = 1.8 x 10-5)
What is 5.0
Explanation: 28 mmol of WA, 18mmol of OH-
Ka = [H+][18]/10
2A(g) + B(g) -- C(g), at the beginning of one trial of this reaction [A] = 4.0, [B] = 1.0
If [B] is decreased to 0.4, what is the value of [A]?
What is 2.8
Explanation: [B] reacted 0.6 to get to 0.4, the stoichiometry of the reaction is 2:1 so [A] must have reacted 1.2, 4 - 1.2 = 2.8
The melting point of CaS > KCl. the explanation for this includes which os the following?
1. Ca2+ is more positively charged than K+
2. S2- is more negatively charged than Cl-
3. The S2- ion is smaller than the Cl- ion
4. The Ca2+ ion is smaller than the K+ ion
What is two and three
Explanation: the strength of ionic bonds is based off the magnitude of charges(Ca2+S2- >), and the + ions are isoelectronic, however Ca has 20 protons and K has 19
In which element below, would you expect the second electron removed to be extraordinarily high compared to the first ionization energy?
1. Ca
2. K
3. Ga
4. Ge
5. Se
What is 2
Explanation: K only has one valence electron, so there would be a large increase for the second electron.
Magnesium hydroxide, Mg(OH)2, has a Ksp = 6.3 ×
10-10. The solubility of Mg(OH)2 will be the lowest in
1.0 L of which of the following?
1. 0.10 M HCl
2. 0.10 M NaOH
3. 0.10 M MgCl2
4. pure H2O
What is 0.10 M NaOH
Explanation: must use the common ion effect.
Ksp = [Mg2+][OH-]2
6.3 x 10-10 = [s][0.1]2
s = 6.3 x 10-8
Mg(OH)2 has a Ksp = 6.3 x 10-10. The solubility of Mg(OH)2 will be the lowest in 1.0L of which of the following?
0.10 M HCL
0.10 M NaOH
0.10 M MgCl2
Pure H2O
What is 0.10 M NaOH
Explanation: the common ion effect, Ksp = [Mg2+][OH-]2. OH- will have a greater effect on decreasing solubility.
The rate for the reaction, N2O(g) + CO(g) → N2(g) + CO2(g), increases in the presence of Pd(s). Which best explains this observation?
(1) Pd increases the activation energy of the
reaction.
(2) Pd absorbs the heat produced in the reaction.
(3) One of the reactants binds on the surface of
Pd, which introduces an alternative reaction
pathway with a lower activation energy.
(4) One of the products binds on the surface of
Pd, which increases the reaction rate by
decreasing the concentration of products in
the mixture.
What is 3
Explanation: increase in rate means that there must be a lower activation energy