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WorksheetsMost Challenging AP Chem
Total questions: 71
Worksheet time: 18hrs 45mins
Which set of atoms/ions could all have the following electron configuration? 1s2 2s2 2p6 3s2 3p6
Na, Na+1, Ne
Ne, Ar, Kr
Ca, Ar, Cl
Ar, K+1, S-2
What are the values of x and y in the formula Alx(CO3)y
x=2 y=3
x=1 y=2
x=1 y=3
x=1 y=1
In which polyatomic ion does the sulfur atom have an oxidation number of +4
hydrogen sulfate
sulfite
sulfate
thiosulfate
In the combustion of methanol, CH3OH, the oxidation number of carbon changes from _________
0 to +2
+2 to 0
changes from -2 to +4
does not change, this is not a redox reaction
In the combustion of methanol, CH3OH, _____________
oxygen is oxidized
oxygen is reduced
carbon is reduced
no elements are oxidized or reduced, this is not a redox reaction
Which net ionic equation represents the chemical reaction between sodium hydroxide and magnesium nitrate in which a precipitate forms?
Na+1(aq) + (NO3)-(aq) --> Na(NO3)(s)
Mg+2(aq) + (OH)-(aq) --> Mg(OH)2(s)
Mg+2(aq) + (NO3)-(aq) --> Mg(NO3)2(aq)
Na+1(aq) + Mg-2(aq) --> Na2Mg(s)
Which chemical formula below is a empirical formula for the molecular formula C6H12O6
CH2O
C2H4O2
C2H4O
C2H3O2
In which polyatomic ion does nitrogen have the highest oxidation number?
ammonium
hydroxide
nitrite
nitrate
In the double replacement reaction between calcium chloride and silver nitrate solutions, a precipitate forms. What compound will be the precipitate?
calcium chloride
calcium nitrate
silver chloride
silver nitrate
What are the coefficicents that correctly balance the chemical equation: C2H6 + O2 --> H2O +CO2
1:3:3:2
4:6:8:1
2:3:4:2
2:7:6:4
What is the formula for the compound dinitrogen tetroxide
N2O4
N4O2
N2O2
N8O4
If a compound has an empirical formula of CH2O and an approximate molar mass of 90 g/mol, what is the correct molecular formula for the compound?
C3 H6 O3
C6 H12 O6
C12 H24 O12
C30 H60 O30
The synthesis of water is represented by the chemical equation below. If 6 moles of hydrogen react with 4 moles of oxygen, which reactant is teh limiting reactant? 2H2 + O2 --> 2H2O
hydrogen
oxygen
neither limits
both limit
A student has a 0.750M silver nitrate solution to use for a reaction. They want the reaction to provide at least 1.50 moles of silver. What is the minimum volume of the silver nitrate solution that should be used?
2.00 * 103mL
2.00mL
1.125mL
1.125L
In the synthesis reaction of calcium oxide from its elements, calcium
is neither oxidized or reduced
is oxidized
is reduced
is solidified
In double replacement reactions where a precipitate is formed, which ion of the choices below will most likely be part of a precipitate?
ammonium ion
lithium cation
iron(iii) cation
nitrate anion
How many electrons does a chromium (iii) ion have?
impossible to determine
21
23
25
Which choice below contains the correct chemical formula: name match?
Cr(PO4)3: CHromium (ii) phosphate
Cr(PO4): chromium phosphate
Cr(PO4): chromium (ii) phosphate
Cr3(PO4)2: chromium (ii) phosphate
Which substance below will likely have a pH lower than 7?
sodium bicarboante
bleach
tap water
lemon juice
Which electron configuration below represents an element with the lowest first ionization energy?
1s2 2s2 2p1
1s2 2s2 2p6 3s2 3p5
1s2 2s2 2p6 3s1
1s2 2s1
According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the
increasing number of electron domains around the central atom
decreasing size of the central atom
decreasing repulsion between hydrogen atoms
increasing number of unshared pairs of electrons around the central atom
Based on Lewis Structures, which molecule below will contain one sigma and two pi bonds?
N2
O2
F2
CO2
Which list below lists the substances in order of increasing intermolecular attraction?
Xe<H2<O2<N2<F2
H2<N2<O2<F2<Xe
H2<Xe<N2<O2<F2
Xe<F2<O2<N2<H2
Which molecule(s) will have bond angles of approximsately 109.5 degrees
i) CH3F ii) H2O iii)SO2 iV) CO2
i
ii
i and ii
i, ii, and iii
Which m/olecule(s) will have bond angles greater than 109.5 degrees?
i) SCl2 ii)CF4 iii) CH2O iv) NH3
i
ii and iv
i, ii, and iv
iii
WHich molecule will demonstrate sp2 hybridization around its central atom?
i)SCl2 ii)CF4 iii) CH2O iv) NH3
i
iii
iv
iii and iv
for which of the following molecules are resonance structures necessary to describe the bonding satisfactorily?
SO2
CO2
H2S
OF2
At 298K and 1 atm, Br2 is a liquid with a high vapor pressure, and Cl2 is a gas. Those observations provide evidence that under the given conditions, the _________
forces between Br2 molecules are stronger than those between Cl2 molecules
forces between Cl2 molecules are stronger than the Cl-Cl bond
Br-Br bond is stronger than the Cl-Cl bond
Cl-Cl bond is stronger than the Br-Br bond
Which molecule represents a hypervalent molecule?
Bf3
SF4
PF3
CF4
Which statement below about the polarity of NF3 and BF3 is correct?
only NF3 has a net dipole (is polar)
only BF3 has a net dipole (is polar)
both NF3 and BF3 have a net dipole (are polar)
both NF3 and BF3 are nonpolar
WHich of the following statements accounts for the statement above about the polarity of the two molecules, NF3 and BF3?
In NF3 each F is joined to N with multiple bonds, whereas in BF3, each F is joined to B with single bonds
N-F bonds are polar, whereas B_F bonds are nonpolar
NF3 is an ionic compound, whereas BF3 is a molecular compound
Unlike BF3, NF3 has a nonplanar geometry due to an unshared pair of electrons on the N atom
Which of the following is the correct net ionic equation for the reaction that occurs when solutions of lead (iv) nitrate and sodium hydroxide are mixed when a precipitate forms
Pb(NO3)2(aq) + 2NAOH(aq) --> 2NaNO3(aq) +Pb(OH)2(s)
Na+(aq) + (OH)-(aq) --> Na(OH)(s)
Pb4+(aq) + 4(OH)-(aq) --> Pb(OH)4(s)
Pb4+(aq) + 4(NO3)-(aq) --> Pb(OH)4(s)
Which instrument of those listed below would not be needed to make 500.0mL of 0.750M calcium nitrate solution starting with solid calcium nitrate and distilled water.
balance
10.0mL pipet
volumetric flask
plastic weighing tray
What mass of calcium nitrate is needed to make 500.0mL of 0.750M solution?
0.3750g
61.53g
82.01g
109.4g
What volume of 0.750M calcium nitrate solution would be needed to make 1.00L of 0.500M calcium nitrate solution?
37.5mL
66.7mL
750.0mL
1.50mL
What type of reaction is the following description of chemical change classified as? A piece of solid magnesium is placed in a solution of hydrochloric acid and a gas is produced.
metathesis: acid-base neutralization
metathesis: gas forming
redox: combustion
redox: single replacement
When a piece of solid magnesium reacts with a solution of hydrochloric acid, what products are produced?
Mg(s) + HCl (aq)
H2(g) + MgCl2(aq)
Cl2(g) + MgH2(aq)
H2(g) + Cl2(g) + Mg(s)
Which element is oxidized?
14H +(aq) + CrO2 2- (aq) + 6Cl-(aq) --> 2Cr +3(aq) + 7H2O(l) + 3Cl2 (g)
chlorine
chromium
oxygen
hydrogen
Which element is reduced?
14H +(aq) + CrO2 2- (aq) + 6Cl-(aq) --> 2Cr +3(aq) + 7H2O(l) + 3Cl2 (g)
chlorine
chromium
oxygen
hydrogen
How many electrons are transferred during the chemical reaction?
14H +(aq) + CrO2 2- (aq) + 6Cl-(aq) --> 2Cr +3(aq) + 7H2O(l) + 3Cl2 (g)
2 electrons are transferred from the dichromate ion to the chromium (iii) cation
2 electrons are transferred from the dichromate ion to the chloride ions
6 electrons are transferred from the chloride ions to the dichromate ion
6 electrons are transferred from the chloride ions to the chlorine molecules
Which statement about the redox reaction best describes the conditions in which it occurred?
14H +(aq) + CrO2 2- (aq) + 6Cl-(aq) --> 2Cr +3(aq) + 7H2O(l) + 3Cl2 (g)
the reaction takes place in acidic solution
the reaction takes place in basic solution
the reaction takes place in a neutral aqueous solution
all reactants and products are either solids, liquids, or gases so no solution exists
WHich of the following statements best describes what is happening in a container when 5.00g of sodium hydroxide (40g/mole) in solution reacts with 5.00g of lead(IV) nitrate (441 g/mol) in solution and visible precipitate forms?
lead (iv) hydroxide precipitates and sodium hydroxide is the limiting reactant
lead (iv) hydroxide precipitates and lead(iv) nitrate is the limiting reactant
sodiu nitrate precipitates and sodium hydroxide is the limiting reactant
the spectator ions are Pb +4 and Na +1
When the reaction between solid magnesium and hydrochloric acid solution occurs, which statement below best describes the movement of electrons during the chemical change?
electrons leave the hydrogen ion in hydrochloric acid and are transferred to solid Mg
electrons leave magnesium ions in solution and are transferred to the chloride ion
electrons leave magnesium atoms as they are transferred to the hydrogen ions in solution
no electrons are transferred in this reaction because the reaction is not a redox reaction.
Which is a redox?
2Al(s) + 3H2SO4(aq) --> Al2(SO)4(aq) + 3H2(g)
2KBr(aq) + Pb(NO3)2(aq) --> 2KNO3(aq) + PbBr2(s)
CaBr2(aq) + H2SO4(aq) --> CaSO4(s) + 2HBr(g)
H+(q) + OH-(aq) --> H2O(l)
The driving force behind a metathesis acid-base neutralization reaction is___________________.
the formation of the molecular compound water
the formation of a slat from the cation of the base and the anion of the acid
the movement of electrons from one element to another
the formation of a precipitate from 2 compounds in solution
Which of the following compounds is a weak electrolyte?
CH3COOH
HBr
CH3OH
NaCl
Which of the following is a non-electrolyte?
NaNO3
HNO3
CH3OH
NH4Cl
When analyzing a hydrocarbon consisting of hydrogen, carbon, and oxygen by combustion it is safe to assume all the oxygen from the hydrocarbon can be found in the carbon dioxide produced
true; oxygen is only found in the hydrocarbon and carbon dioxide
false; oxygen is also found in water and comes from the air
false; oxygen is not found in carbon dioxide
true; oxygen from the air is not involved in a combustion reaction
Determine the enthalpy change for the following reaction at 298K.
4NH3(g) + 3O2(g) --> 2N2(g) + 6H2O(g)
-290 kJ/mol rxn
-580 kJ/mol rxn
-1270 kJ/mol rxn
-1640 kJ/mol rxn
A system is defined as a solid piece of ice at -1.0 degrees celsius. The piece of ice melts to a puddle of water at 1.0 degrees celsius with the same mass as the ice while sitting on a counter. WHat has happened to the total internal energy of the sytem and the total entropy of the system?
ΔE increases, ΔS increases
ΔE decreases, ΔS decreases
ΔE increases, ΔS decreases
ΔE decreases, ΔS increases
The sign of ΔH for the process H2O(g) --> H2O (l) is
positive and the process is endothermic
negative and the process is endothermic
positive and the process is exothermic
negative and the process is exothermic
Which of the following mistakes would lead to an enthalpy calculation in kJ/mol for the reaction that is too high?
NaOh(aq) + HCl(aq) --> NaCl9aq) + H2O(l)
students assume their coffee cup calorimeter absorbs no heat
students use 1.00 M solutions instead of 2.00M solutions
students determine the temperature of the reaction by waiting 180 seconds and then putting the thermometer in he reaction mixture
students base their calculations on 50mL of eachs olution but use 100mL by accident
If a process is endothermic and taking place in solution, what evidence would indicate this?
the solution would maintain constant volume
the solution would increase in temperature
the solution would decrease in temperature
the temperature of the solution would remain constant
Choose the statement about the bonds in the products and reactants that is most correct.
CH3OH(g) --> CO(g) + 2H2(g)
ΔH = 91kJ/mol rxn
the sum of the bond enthalpies in the bonds of the reactant is greater than the sum of the bond enthalpies in the bonds of the products.
the sum of the bond enthalpies in the bonds of the reactant is less than the sum of the bond enthalpies in the bonds of the products
the sum of the bond enthalpies in the bonds of the reactant is equal to the sum of the bond enthalpies in the bonds of the products
the entropy of the system decreases so enthalpy change also has to be positive
Which molecule below should have the lowest gas phase absolute entropy at 25 degrees celsius?
H2
CH4
C2H4
C2H6
In living systems, the conversion of ADP to ATP
is a spontaneous process and fuels other nonspontaneaous reactions
is nonspontaneous and uses free energy from the oxidation of glucose to occur
is a nonspontaneous process and uses free energyf rom transport of oxygen
is coupled with the conversion of ATP to ADP as a source of free energy
Which response includes all the processes that are accompanied by an increase in entropy?
1.H2O(l) --> H2O(s)
2.Br2(l) --> Br2(g)
3.2SO2(g) + O2(g) --> 2SO3(g)
4.H2O2(l) --> H2O (l) + (1/2)O2(g)
1, 3, 4
2, 4
2, 3, 4
1, 3
How much energy is required to melt 64 g of water at 273 K?
0.59kJ
33kJ
21.4kJ
1643kJ
Which of the following best explains why more energy is required for the process occurring at 273 K for water than for the process occurring at 90 K for methane?
intermolecular attractions are completely overcome during vaporization
intermolecular attractions in the solid phaseare stronger than in the liquid phase
intermolecular attractions between methane molecules are weaker than between water molecules
vaporization involves a large increase in temperature
A vessel contains Ar(g) at a very high pressure. Which of the following statements best helps to explain why the measured pressure is significantly greater than the pressure calculated using the ideal gas law?
the molar mass of argon is fairly large
a significant number of Ar2 molecules form
the attractive forces among Ar atoms cause them to collide with the walls of the container with less force
the combined volume of Ar atoms is too large to be negligible compared with the total volume of the container
two moles of chlorine gas at 20.0 degrees celsius are heated to 350 degrees celsius while the volume is kept constant. The density of the gas
increases
decreases
remains the same
Two balloons are at the same temperature and pressure. One contains 35.5g of chlorine gas and the other contains 39.95 g of argon. Pick the false statement:
the density of the chlorine sample is greater than the density of the argon sample
the average speed of the chlorine molecules is greater than the average speed of the argon atoms
the volume of the chlorine balloon is smaller than the volume of the argon balloon
equal numbers of moles of the gases He, Ar, and Ne are placed in a glass vessel at room temp. If the vessel has a pinhole-sized leak, which of the following will be true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused?
He<Ne<Ar
He<Ar<Ne
Ne<Ar<He
Ar<He<Ne
A sample of 5.2 grams of an ideal gas at 121 degrees celsius and 1.0 atm pressure has a volume of 1.5 liters. What value is closest to the molar mass of the gas?
20.0 g/mol
65 g/mol
112 g/mol
145 g/mol
Which gas would be expected to have a density smaller than that of argon under the same conditions?
i: carbon dioxide
ii: methane (CH4)
iii: chlorine
i only
ii only
iii only
ii and iii
Which gas and set of conditions will show the largest deviation from ideal gas behavior?
chlorine gas at 200 atm and 500 K
argon gas at 350 atm and 100 K
chlorine gas at 350 atm and 100 K
argon gas at 350 atm and 100 K
If equal masses of O2(g) and Br(g) are in separate containers of equal volume and temperature, which one of the following statements is true?
the pressure in the O2 container is greater than that in the HBr container
there are more HBr molecules than O2 molecules
the pressures of both gases are the same
the avg velocity of the O2 molecules is less than that of the HBr molecules
Which gas has particles with the greatest average speed at 25 degrees celsius?
CH4
Kr
N2
Ar
Which substance below is most likely to be a gas at room temperature?
H2O
NH3
CaCO3
Cu
Two sealed containers with equal volume contain two gases at the same temperature and presssure. One container contains 12.60 g of gas and the other container contains 48.2 g of gas. Which container has a gas with a lower molar mass?
the container w/ 12.60 grams of gas
the container w/ 48.2 g of gas
both containers contain a different number of moles
the average speed of the particles in both containers is the same
A 2.0L container will hold about 4.0g of which of the following gases at 0 degrees celsius if the gas exerts a pressure of 1.0atm
SO2
N2
CO2
NH3
