Unit 3
A list of intermolecular forces from weakest to strongest.
What are LDF, dipole-dipole, H bonding, ion-dipole?
The coefficient of H3PO4:
Ca3(PO4)2(s) + H3PO4(l) -> Ca(H2PO4)2(s)
What is 4?
K = 2.0 x 105 for the reaction. This is the value of K for the reverse reaction.
H2 + Br2 <---> 2 HBr
What is 5.0 x 10-6?
At this point on a weak acid-strong base titration curve, the concentration of the weak acid and its conjugate base are approximately equal.
What is the half-equivalence point?
This compound has a mass ratio of Cr to O closest to 1.62 to 1.00.
CrO3, CrO2, Cr2O, Cr2O3
What is CrO2?
List the IMF in methylamine, CH3NH2.
What are LDF, dipole-dipole, H bonding?
Name the type of reaction is shown, and justify your answer.
H2Se(g) + 4 O2F2(g) -> SeF6(g) + 2 HF(g) + 4 O2(g)
What is redox?
The oxidation number of Se changes from -2 to +6 (or oxygen changes from +1 to 0).
Write the K expression for the reaction
Ag+(aq) + 2NH3(aq) ---> [Ag(NH3)2]+(aq)
K = [[Ag(NH3)2]+] / [Ag+] / [NH3]2
H3PO4 Ka = 7 x 10-3
H2PO4- Ka = 8 x 10-8
HPO42- Ka = 5 x 10-13
What two substances (at least one from the list above) would best make a buffer with a pH=9?
What is H2PO4- + HPO42-?
This is the geometry & hybridization of the SO3 molecule.
What is trigonal planar and sp2?
When 70. milliliters of 3.0 M Na2CO3 is added to 30. milliliters of 1.0 M NaHCO3 the resulting concentration of Na+ is...
What is 4.5 M?
Write the net ionic equation when a 5.0 g sample of Mg is placed in hydrochloric acid. Include states of matter.
What is Mg(s) + 2H+(aq) -> Mg2+(aq) + H2(g)?
2 SO3(g) <---> 2 SO2(g) + O2(g)
After reaching equilibrium, some pure O2(g) is injected into the vessel at constant temperature. After equilibrium is reestablished, this is lower compared to its value at the original equilibrium.
What is the amount of SO2(g)?
This is the pH of a solution prepared by the addition of 10. mL of 0.002 M KOH(aq) to 10. mL to distilled water.
What is 11?
This number of moles of O2 is needed to produce 14.2 g of P4O10 from P.
MM of P4O10 = 284
What is 0.250 mole?
A 2 L container will hold about 4 g of one of the following gases at 0oC and 1 atm: SO2, N2, CO2, NH3. Identify the gas.
What is CO2?
# of electrons transferred in the reaction:
2MnO4-(aq) + 10Br-(aq) + 16H+(aq) -> 2Mn2+(aq) + 5Br2(aq) + 8H2O(l)
What is 10?
2MnO4- -> 2Mn2+
2MnO4- -> 2Mn2+ + 8H2O
16H+ + 2MnO4- -> 2Mn2+ + 8H2O
10e- + 16H+ + 2MnO4- -> 2Mn2+ + 8H2O
Equal volumes of 0.1 M AgNO3(aq) and 0.4 M NH3(aq) are mixed and reach equilibrium. List the equilibrium concentrations of the reactants & products below in order from least to greatest.
Ag+(aq) + 2NH3(aq) ---> [Ag(NH3)2]+(aq); K = 1 x 107
What is [Ag+] < [[Ag(NH3)2]+] < [NH3] ?
*Make an ICE table & solve for x (0.100).
This is the pH of a 0.010 M solution of HCN? (Ka = 4.0 x 10-10).
What is 5.20?
Pi bonding occurs in all but this one species:
CO2, CN-, C6H6, CH4
What is CH4?
FRQ: Use principles of atomic structure and/or chemical bonding to explain each of the following. In each part, your answers must include references to both substances.
a) The atomic radius of Li is larger than that of Be.
b) The C-C bond energy in C2H4 is greater than it is in C2H6.
c) The BP of Cl2 is lower than Br2.
a) Li has fewer protons than Be, causing a less Fattract for e-.
b) C2H4 has a C=C & C2H6 has a C-C. Double bonds require more energy to break because it is a stronger bond.
c) Both have LDF, but Br2 has a larger, more polarizable electron cloud, causing it to have greater LDF & therefore higher BP than Cl2.
A 1.2359 g sample of a compound containing C, H, N, & O is burned in excess oxygen. 2.241 g of CO2 is formed. The combustion analysis showed that the sample contained 0.0648 g of H. The mass percent of N is found to be 28.84%. Determine the empirical formula of the compound.
What is C4H5N2O?
Ag2C2O4(s) is slightly soluble in water (Ksp=5.40 x 10-12).
a) Write the expression for the Ksp for Ag2C2O4.
b) Calculate the molar solubility of Ag2C2O4 in neutral distilled water.
c) The molar solubility of Ag2C2O4 increases when it is dissolved in 0.5 M HClO4(aq) instead of neutral distilled water. Write a balanced, net-ionic equation for the process that account for this.
a) Ksp = [Ag+]2[C2O42-]
b) S = 1.11 x 10-4 M
Use an ICE table to get K = (2S)2(S) ; 5.40 x 10-12 = 4S3
c) C2O42- + H+ ---> HC2O4- OR
C2O42- + H3O+ ---> HC2O4- + H2O(l)
A student titrates 45.00 mL of the stock solution with 1.25 M HCl. Ka = 1.7 x 10-5.
a) Write the net ionic equation for the reaction.
b) 29.95 mL of 1.25 M HCl is required to reach the equivalence point. Calculate [KC6H7O2] in the stock solution.
c) The pH at the equivalence point is 2.54. Calculate the pH at the half-equivalence point.
a) H+ + C6H7O2- <---> HC6H7O2
b) 0.832 M
n=0.0374 mol HCl = MV
c) pH = pKa = -log(1.7 x 10-5) = 4.77
This property generally decreases across the periodic table from sodium to chlorine.
What is atomic radius?