Semester 2 AP Chem
6
...P4O10 + ...Ca(OH)2 = ...Ca3(PO4)2 + ...H2O when the chemical equation above is balanced, in terms of lowest whole-number coefficients, the coefficient for H2O is
Mg3X2
1s^2 2s^2 2p^6 3s^2 3p^3 Atoms of an element, X, have the electron configuration shown above. The compound most likely formed w/ magnesium, Mg, is
-46 kJ/mol
2NH3 = 3H2 + N2 (H298 = 92 kJ/mol) According to the info above, what is the standard enthalpy of formation, H, for NH3 at 298 K?
.015 mole
3Ag(s) + 4HNO3 = 3AgNO3 + NO(g) + 2H2O the reaction of silver metal and dilute nitric acid proceeds according to the equation above. if .10 mole of powdered silver is added to 10. mL of 6.0-molar nitric acid, the number of moles of No gas that can be formed is
1 x 10^-7
A .10M solution of a weak monoprotic acid has a pH equal to 4.0. The ionization constant of, Ka, of the acid is
1.0 M
A .20 mol sample of MgCl2 and a .10 mol sample of KCl are dissolved in water and diluted to 500 mL. What is the concentration of Cl in the solution?
3 atm
A 2L sample of N2 and a 1 L sample of Ar, each originally at 1 atm and 0C, are combined in a 1L tank. If the temp is held constant, what is the total pressure of the gases in the tank?
CuSO4 (aq)
A white precipitate forms when BaCl2(aq) is added to an unknown blue solution. What could be the identity of the blue solution?
Ba
Atoms of Mg combine w/ atoms of F to form a compound. What atoms combine w/ atoms of F in the same ratio?
I, II, and III
C2H4 + H2 = C2H6 C2H4 is reduced by H2 in the presence of a solid platinum catalyst, as represented by the equation above. Factors that could affect the rate of the reaction include which of the following? I. Changes in the partial pressure of H2. II. Changes in the particle size of the platinum catalyst. III. Changes in the temp of the reaction system
2.00 mol
C3H8 + 5O2 = 3CO2 + 4H2O In the reaction represented above, what is the total number of moles of reactants consumed when 1.00 mole of CO2 is produced?
-75.8 kJ mol-1
CH4(g) + 2O2(g) = CO2(g) + 2H2O(l) Hrxn= -889.1kJmol-1 Hf H2O(l) = -285.8 kJ mol-1 Hf CO2(g) = -393.3 kJ mol-1 What is the standard heat of formation of methane as calculated from the data above?
decreasing the temperature
CuO(s) + H2(g) = Cu(s) + H2O (g) H<0 The substances in the equation above are at equilibrium at pressure and temperature. The equilibrium can be shifted to favor the products by
F2 < HCl < HF
F2, HCl, and HF is order of increasing boiling point
100 mL volumetric flask
For an experiment, a student needs 100.0mL of a .4220M NaCl. If the student starts w/ NaCl and distilled water, which of the following pieces of lab glassware should the student use to prepare the solution w/ the greatest accuracy?
A
Gases generated in a chemical reaction are sometimes collected by the displacement of water. Which of the following gases can be quantitatively collected by this method? A) H2 B) CO2 C) HCl D) SO2 E) NH3
20 g
H2 + F2 = 2HF In the reaction represented above, what mass of HF is produced by the reaction of 3.0 x 10^23 molecules of H2 w/ excess F2?
CO3 2- (aq)
HSO4 + CO3 = SO4 + HCO3 The reaction represented above is observed to proceed spontaneously to the right in aqueous solution. In this system the strongest base is
B
In which flask do the molecules have the greatest average speed? A) T= 30C; P= 1atm B) T= 50C; P= 0.5atm C) T= 40C; P= 2atm D) T= 50C; P= 1atm E) T= 40C; P= 0.5atm
SiCl4(l)
London (dispersion) forces are the only type of intermolecular forces in what pure liquid?
the rate of reaction increases
Rate= k[H3AsO4] [I-] [H3O+] According to the rate law for the reaction, an increase in the concentration of the hydronium ion has what effect on the reaction at 25C?
1
The experimental rate law for the reaction at 25C is Rate= k[H3AsO4] [I-] [H3O+] What is the order of the reaction w/ respect to I-?
B
The reaction between a Bronsted-Lowry acid and a Bronsted-Lowry base A) 2C6H6 + 15O2 = 12 CO2 + 6H2O B) C2H3O2 + H3O = HC2H3O2 + H2O C) 4H + 4CO + O2 + 24NH3 = 4CO(NH3)6 + 2H2O D) CaCO3 = CaO + CO2 E) 2H2O2 = O2 + 2H2O
E
The reaction in which a single species is both oxidized and reduced A) 2C6H6 + 15O2 = 12 CO2 + 6H2O B) C2H3O2 + H3O = HC2H3O2 + H2O C) 4H + 4CO + O2 + 24NH3 = 4CO(NH3)6 + 2H2O D) CaCO3 = CaO + CO2 E) 2H2O2 = O2 + 2H2O
C
Which flask contains the sample w/ the greatest density? A) T= 30C; P= 1atm B) T= 50C; P= 0.5atm C) T= 40C; P= 2atm D) T= 50C; P= 1atm E) T= 40C; P= 0.5atm
B
Which flask contains the smallest number of moles of gas? A) T= 30C; P= 1atm B) T= 50C; P= 0.5atm C) T= 40C; P= 2atm D) T= 50C; P= 1atm E) T= 40C; P= 0.5atm
N
Which of the following elements has the largest first ionization energy? A) Li B) Be C) B D) C E) N
true
X(g) + Y(g) = Z(g) true/false for the chemical system represented above when the system has reached a state of equilibrium at constant temperature and pressure: the forward and reverse reactions occur at the same rate.
Y < Z < X
X: CH3CHOHCH2OH Y: CH3CH2Ch2CH3 Z: CH3CH2CHOHCH3 Considering the structures of the three compounds, X, Y, and Z, shown above, the ranking of their solubility in water from least to greatest is what?
NaNO3
a 0.1-molar aqueous solution of what is neutral?
.160 M
a 20.0-mL sample of .200 M K2CO3 solution is added to 30.0 mL of .400 M Ba(NO3)2 solution. Barium carbonate precipitates. the concentration of barium ion, Ba^+2, in solution after reaction is
C4H6
a 27.0 gram sample of an unknown hydrocarbon was burned in excess oxygen to form 88.0 grams of carbon dioxide and 27.0 grams of water. what is a possible molecular formula of the hydrocarbon?
HCO3- and CO3^-2
a Bronsted-Lowry acid-base pair
vapor pressure of the water
a compound is heated to produce a gas whose molar mass is to be determined. the gas is collected by displacing water in a water-filled flask inverted in a trough of water. what is necessary to calculate the molar mass of the gas but does not need to be measured during the experiment?
2.0 atm
a sample of gas has a volume of 1.0L at 300 K and 2.0 atm. if the volume and the absolute temperature are both doubles, what is the final pressure of the sample?
NH4+
a solution containing what ions will give off a pungent odor when added dropwise to warm NaOH(aq)
42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2 L
a student wishes to prepare 2.00 liters of .100 M KIO3. the proper procedure is to weigh out
vapor pressure
as intermolecular forces become stronger for pure liquids, what tends to decrease?
0.77
at 20C, the vapor pressure of toluene is 22 mm Hg and that of benzene is 75 mm Hg. an ideal solution, equimolar in toluene and benzene, is prepared. at 20C, what is the mole fraction of benzene in the vapor in equilibrium w/ this solution?
D
based on periodic trends, which of the following atoms has the largest atomic radius? A) K B) Ga C) Br D) Cs E) Te
NH4+
cannot act as both a Bronsted-Lowry acid and a Bronsted-Lowry base
H2O2 < O3 < O2
compounds listed correctly in order of increasing strength of their oxygen-to-oxygen bonds
Cu2O
contains an element in a +1 oxidation state
HNO3 < NaNO3 < Na2CO3 < NaOH
correctly ranked substances in order of increasing pH of the solution they produce
false
each of three flexible vessels contains a gas at the same temperature and pressure. the first contains 2.0 g of H2(g), the second contains 32.0 g of O2(g), and the third contains 44.0 g of CO2(g). true/false: the average speed of the molecules in each of the vessels is the same.
P H2 < P N2 < P Ar
equal numbers of moles of H2(g), Ar(g), and N2(g) are placed in a glass vessel at room temperature. if the vessel has a pinhole-sized leak, what is true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused?
BH3
has a central atom w/ less than an octet of electrons
NH3
has a trigonal-pyramidal molecular geometry
CO3^-2
has polar bonds but a zero dipole moment
H2O
has two lone pairs of electrons
1.0 x 10^-4
if a 1.0M solution of HA, a weak acid, has a pH of 2.0, then the value of Ka, the acid-dissociation constant, for HA is closest to
4%
if the acid dissociation constant, Ka, for an acid HA is 8 x 10^-4 at 25C, what percent of the acid is dissociated in a .50M solution of HA at 25C?
AlF3
in the formation of 1.0 mole of crystalline solids from gaseous ions, the most energy is released by
BH3
is predicted to have the largest bond angle
I2
longest bond length
catalyst
lowers the activation energy by changing the mechanism of the reaction
critical temperature
lowest temperature above which a substance cannot be liquefied at any applied pressure
CCl4
molecule that contains polar covalent bonds but is a nonpolar molecule
collisions of the gas molecules w/ the walls of the container
most directly responsible for the pressure of a gas in a sealed container
D
on the basis of trends in the periodic table, an atom of which of the following elements is predicted to have the lowest first ionization energy? A) Ar B) Cl C) K D) Rb E) I
Br
one atom of an element w/ the smallest radius
B - F
one of the most polar single covalent bonds
S
oxides of what element is responsible for acid rain?
2NO2 = N2O4
reaction mixture at equilibrium that would reduce the volume of the container at constant temp and cause the equilibrium to shift toward the products
a network solid w/ covalent bonding
solid silicon dioxide, SiO2, is
I-
species that cannot function as an oxidizing agent?
46.0 g/mol
the density of an unknown gas is 4.20 grams per liter at 3.00 atm and 127C. What is the molar mass of this gas?
trigonal planar
the geometry of the SO3 molecule is best described as
density of the solution
the molality of the glucose in a 1.0M glucose solution can be obtained by using what?
+4
the oxidation number of silicon in the compound Na2Mg2Si6O15 is
11
the pH of .1M ammonia is approximately
HF molecules tend to form hydrogen bonds
the relatively high boiling point of HF can be correctly explained by what?
true
true/false: the halide ions are larger than their respective halogen atoms.
.10 M potassium sulfate, K2SO4
what aqueous solutions has the highest boiling point?
NH3
what compound is amphoteric?
Zn
what element is most likely to be in the +2 oxidation state in its compounds?
K
what element is never found pure in Earth's crust?
xenon
what gas deviates more from ideal gas behavior because of attractive forces between atoms
the positive charge of an atom is concentrated in a small region
what is a correct interpretation of the results of Rutherford's experiments in which gold atoms were bombarded w/ alpha particles?
SO2
what is involved in the environmental problem known as acid rain?
+6
what is the oxidation number of Cr in CrO4^-2
.250 mole
what number of moles of O2 is needed to produce 14.2 grams of P4O10 from P?
Br2
what pure substance is a reddish-brown liquid at 298K and 1atm?
H2O + HSO4- = H2SO4 + OH-
what reaction doesn't proceed significantly to the right in aqueous solutions
H3O+ ions
what species are in the greatest concentration in a .100 M solution of H2SO4 in water?
n=6 to n=4
what transition of an electron in a hydrogen atom will emit a photon that has the highest frequency?
4.5 M
when 70 mL of 3.0 M Na2CO3 is added to 30 mL of 1.0 M NaHCO3, the resulting concentration of Na+ is
E
which of the following indicators is most appropriate for determining the equivalence point in the titration of a weak acid w/ a strong base? A) Thymol blue 1.2-2.8 B) Methyl orange 3.1-4.4 C) Methyl red 4.4-6.2 D) Bromcresol purple 5.2-6.8 E) m-cresol purple 7.6-9.2
2
...LiHCO3 (aq) + ...H2SO4(aq) = ...Li2SO4(aq) + ...H2O(l) + ...CO2(aq) When the equation above is balenced and the coefficients are reduced to lowest whole-number terms, what is the coefficient of H2O(l)?
2
...MnO4-(aq) + ...NO2-(aq) + ...H2O(l) = ...MnO2 + ...NO3-(aq) + ...OH-(aq) when the redox equation shown above is balanced by using coefficients reduced to lowest whole numbers, the coefficient for MnO4- is