Chem Final
Elements arranged by ________________
# of protons and atomic #
A compound that is very unstable and decomposes explosively could have a heat of formation of Responses -5 kJ/mol -250 kJ/mol +250 kJ/mol +5 kJ/mol
+250 kJ/mol
Which equation correctly represents the first ionization of aluminum (without the energy term)? Responses Al(g) → Al-1(g) + e- Al(g) + e- → Al-1(g) Al-1(g) → Al(g) + e- Al(g) → Al+1(g) + e- Al+1(g) + e- → Al(g)
Al(g) → Al+1(g) + e-
Which statement(s) about N2 is/are true? Responses It is a gas at room temperature. It has 1 sigma and 2 pi bonds between the 2 atoms. It has 2 sets of lone electron pairs. All of the above are TRUE.
All of the above are TRUE.
Which of the following statements is/are correct? Responses In an acidic solution, [H+] > [OH-]. In a basic solution, [OH-] > [H+]. In a neutral solution, [H+] = [OH-]. Two of the above statements (A-C) are correct. All of the above statements (A-C) are correct.
All of the above statements (A-C) are correct.
Which pair of elements has the most similar chemical properties? Responses As and Se As and P As and Br C and F
As and P
In class we learned that the value of Kw is 1 x 10-14 at 25ºC. As is true of Keq and Kp, this value is temperature dependent, meaning Kw will change with different temperatures. At 60ºC, the value of Kw is 1 x 10-13. Use this information to select the best answer for the following equation: 2 H2O(l) ↔ H3O+(aq) + OH-(aq) Responses As written, the reaction is exothermic. As written, the reaction is endothermic. There is not enough information to determine exothermic or endothermic.
As written, the reaction is endothermic.
Consider the freezing of liquid water at -10ºC. For this process, what are the signs of ∆H, ∆S, and ∆G? Responses -, +, 0 -, +, - +, -, - +, -, 0 -, -, -
-, -, -
Given the following data: 2CO(g) + O2(g) → 2CO2(g) DH = -566 kJ C(s) + O2(g) → CO2(g) DH = -393 kJ the standard enthalpy change of formation DHf for CO, in kJ/mol, would be Responses -221 -110 -960 +173
-110
2HCl + F2 ---> 2HF + Cl2 Bond Energy H-Cl 431 F-F 155 H-F 567 Cl-Cl 242 What is the enthalpy change
-359 kJ
The thermochemical equation for the production of water is: 2 H2(g) + O2(g) → 2 H2O(l) + 136.64 kcal The DHf for water(l) is Responses +136.64 kcal/mol -68.32 kcal/mol -136.64 kcal/mol +68.32 kcal/mol
-68.32 kcal/mol
The combustion of methanol takes place according to the reaction: 2CH3OH(l) + 3O2(g) → 2CO2 (g) + 4H2O(l) Compute ∆H for the combustion of ONE MOLE of methanol under standard conditions, given the following standard heats of formation: ∆Hºf for CH3OH (l) = -238.5 kJ/mol ∆Hºf for CO2 (g) = -393.83 kJ/mol ∆Hºf for H2O (l) = -285.6 kJ/mol Responses -1453.0 kJ/mol -726.5 kJ/mol +1453.0 kJ/mol none of these +726.5 kJ/mol
-726.5 kJ/mol
How many moles of NaOH would be needed to titrate 20.0 ml of a 0.50 M solution of HCl? Responses 0.01 moles 10.0 moles 40.0 moles Not enough information
0.01 moles
15g sample of lead merges from 22 to 37 with 29J of heat added. what is the specific heat capacity of the lead?
0.13 J/g degrees C
Consider the reaction: 2 HF(g) ↔ H2(g) + F2(g) (K = 0.01) Given 1.00 mole of HF(g), 0.386 mole of H2(g), and 0.750 mole of F2(g) are initially mixed in a 5.00 L flask, determine the reaction quotient Q. Responses none of these 0.0579 0.0724 0.290 2.14
0.290
Given the following reaction: 2NaHCO3 --> H2O (g) + CO2 (g) + Na2CO3 (s) How many total L of gas are produced if 2.00 g. of NaHCO3 (mm=84.007g/mol) decomposes at 29 degrees C and 769 torr? Responses 0.368 L 2.154 L 0.584 L 0.292 L 1.8912 L
0.584 L
Consider a system of four gases. The equilibrium concentration of each product is 1.3 M. The equilibrium concentrations of the reactants are equal. The equilibrium is: A + B ↔ C + D Keq = 2.6 What is the equilibrium concentration of gas A? Responses 0.20 M 2.5 M 1.2 M 0.81 M 1.6 M
0.81 M
To produce Sp^3, ___S and ___P must be mixed
1 S 3 P
A solution with pH of 2 is how many times more acidic than a solution with pH of 5? Responses 3 0.4 10,000 1,000 7
1,000
What is the heat capacity of mercury if 167 J is required to change the temperature of 15.0 g of mercury from 25.0 ºC to 33.0 ºC? Responses 6.92 x 10-3 J/gºC 1.12 x 10-2 J/gºC 0.445 J/gºC 1.39 J/gºC 313 J/gºC
1.39 J/gºC
How many cal would it take to raise 200 mL of water from 20 to 25ºC (hint: 1 cal = 4.18 J) Responses 200 cal 5 cal 1000 cal 1 cal
1000 cal
The bond angle in H2Se is closest to: Responses 104.5º 109.5º 120º 180º 90º
104.5º
The bond angle in the CH2Cl2 molecule is: Responses 180 120 109.5 90 160
109.5
Calculate the pH of 0.208 M NaOH(aq). Hint: Sodium hydroxide is a strong base. Responses 0.682 2.080 -1.140 13.3 1.570
13.3
What is the pH of a solution prepared by dissolving 116.2 g NaOH in enough water to make 3.750 L of solution? Hint: NaOH is a strong base. Responses 0.11 14.11 13.89 12.31 None of these
13.89
The pressure, in atm, exrted by 1.85 mol of an ideal gas placed in a 3.00 L container at 35.0°C? Responses 15.59atm 1.77 atm 0.06414 atm 157900 atm 1.931 atm
15.59 atm
For the reaction: Cl2O(g) + 3/2 O2(g) → 2 ClO2(g) ∆H = 126.4 kJ and ∆S = -74.9 J/K At 373ºC, what is ∆G? Hint: be careful of units! Responses 156.6 kJ 78.0 kJ 174.8 kJ 154.3 kJ 48.5 kJ
174.8 kJ
When 0.40 mole of SO2 and 0.60 mole of O2 are place in an evacuated 1.00 L flask, the following reaction occurs: 2 SO2(g) + O2(g) ↔ 2 SO3(g) At equilibrium the flask is found to contain 0.30 mole of SO3. Based on these results, the equilibrium constant Kc, for the reaction is Responses 20. 2.0 10. 1.2 6.7
20.
The number of valence electrons in SO3, is Responses 24 18 32 40
24
Ionization energies vary most between ______________________________
2nd and 3rd of Mg
Consider the following compounds: CO NH3 CO2 CH4 H2 How many of the compounds are nonpolar? Responses 3 2 1 4 5
3
IE1= 577 IE2= 1815 3=2740 4=11,600 5=15,000 How many valence Electrons?
3
Lewis structure of CO3-2 has ___ sigma and ___ pi
3 sigma 1 Pi
At a given temperature, K = 0.033 for the equilibrium: PCl5(g) ↔ PCl3(g) + Cl2(g) What is the K for: PCl3(g) + Cl2(g) ↔ PCl5(g) Responses 0.033 33 30. . 0.00109 920
30
A gas occupies a volume of 40.0 mL at 734.8 mm Hg and 22°C. The gas is collected by displacement of water and the water level inside the eudiometer is the same as that outside. What is the volume of dry gas at STP? The vapor pressure of water. at 22°C is 20. mm Hg. Responses 12.0 mL 34.8 mL 51.23 mL 24.0 mL
34.8 mL
Given the following reaction: H2O(g) + C(s) + 32 kcal → CO(g) + H2(g) The heat input required to break the bonds in one mole of graphite (pure carbon) and one mole of steam is 390 kcal. Therefore, the formation of bonds in the products releases Responses 179 kcal 422 kcal 211 kcal 358 kcal
358 kcal
The pH of a solution at 25ºC in which [H+] = 3.3 x 10-5 M is: Responses 4.48 3.30 9.52 4.76
4.48
Consider the reaction: C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l) ∆H = -1370 kJ When a 15.1 g sample of ethyl alcohol (molar mass = 46.1) is burned, how much energy is released as heat? Responses 0.449 kJ 2.25 x 103 kJ 196 kJ 4.49 x 102 kJ 1.02 x 103 kJ
4.49 x 10 2 kJ
Calculate the [H+] in a solution that has a pH of 2.23. Responses 2.2 M 11.8 M 5.9 x 10-3M 1.7 x 10-12 M
5.9 x 10-3M
Under which of the following conditions of temperature and pressure will H2 gas be expected to behave most like an ideal gas? Responses 50 K and 0.10 atm 50 K and 5.0 atm 500 K and 0.10 atm 500 K and 50 atm
500 K and 0.10 atm
18. Consider the system: 2 CO(g) + O2(g) ↔ 2 CO2(g) Species Equilibrium Concentration (moles/L) CO 2.0 O2 1.0 CO2 16 What is the value of the equilibrium constant, Keq? Responses 64 128 32 8.0
64
The pH at the equivalence point of the titration of a strong acid with a strong base is: Responses 3.9 4.5 7.0 8.2 none of these
7.0
A gas is collected in a eudiometer by displacement of water. The water column inside is 108.8 mm lower than that outside the tube. The mercury equivalent of this difference is Responses 25 mm 52.4 mm 8.0 mm 108.8 mm
8.0 mm
Which of the following describes the relationship of pH to [OH-]? Responses As the pH decreases, [OH-] decreases. As the pH decreases, [OH-] increases. As the pH increases, [OH-] increases. A and C
A and C
Which of the following statements is correct? Responses BREAKING BONDS REQUIRES ENERGY; MAKING BONDS RELEASES ENERGY. The total energy change for the reaction is the net difference between the cost of breaking bonds and the release of energy when new bonds are formed. BREAKING BONDS RELEASES ENERGY; MAKING BONDS REQUIRES ENERGY. The total energy change for the reaction is the net difference between the cost of making new bonds and the release of energy when bonds are broken. BOTH BREAKING AND MAKING CHEMICAL BONDS RELEASE ENERGY. The total energy released is the sum of energy from making and breaking bonds. BOTH BREAKING AND MAKING CHEMICAL BONDS REQUIRES ENERGY. The total energy absorbed is the sum of the energy cost from making and breaking bonds.
BREAKING BONDS REQUIRES ENERGY; MAKING BONDS RELEASES ENERGY. The total energy change for the reaction is the net difference between the cost of breaking bonds and the release of energy when new bonds are formed.
Which of the following elements has the lowest first ionization energy? Responses Ba Ca Si P Cl
Ba
Which of the following correctly represents the electron affinity of bromine (without the energy term)? Responses Br(g) + e- → Br-1(g) Br2(g) + 2e- → 2Br-1(g) Br2(g) + e- → Br-1(g) Br(g) → Br+1(g) + e- Br+1(g) + e- → Br(g)
Br(g) + e- → Br-1(g)
Of the following, ______ has the highest boiling point. Responses N2 H2 Cl2 Br2 O2
Br2
The following molecules all have polar bonds. Which is nonpolar because of geometric symmetry? Responses HF H2O NH3 CCl4
CCl4
Of the following substances, only ______ has London Dispersion forces as its only intermolecular force. Responses CH4 H2S NH3 CH3OH HCl
CH4
A 2 L container will hold about 4 g of which of the following gases at 0°C and 1 atm? Responses SO2 N2 CO2 C4H8 NH3
CO2
Which of the compounds below is the best example of a molecular solid held together primarily by dispersion forces? Responses H2O(s) CO2(s) Na2O(s) KI(s)
CO2(s)
Isoelectronic series increasing radius.
Ca+2<K+1<Ar<Cl-1
Na reacts with X ---> Na3X What will Ca with X form?
Ca3X2
______ is the most ionic m character based on EN
CaF2
metal oxides in H2O ______ form acidic compounds. DO DONT
DONT
Which of the following statements is FALSE? Responses Electron affinities are usually negative. Ionization energies are always positive. For any atom with at least two electrons, the first ionization energy is always smaller than the second ionization energy. Electron affinities are always negative.
Electron affinities are always negative
Which of the following represents the activity of the halogens from most active to least active? Responses I > Br > Cl > F F > Cl > Br > I. F > Br > Cl > I I > Cl > Br > F
F > Cl > Br > I.
What is the correct order from LARGEST to SMALLEST for the radii of the following isoelectronic series: Ne, Na+1, F-1 All options below appear from Largest to Smallest Responses Na+1 > F-1 > Ne F-1 > Ne > Na+1 Na+1 > Ne > F-1 F-1 > Na+1 > Ne
F-1 > Ne > Na+1
Which among the following bonds is polar covalent? Responses Br and Br K and Br H and Cl Na and O
H and Cl
In which one of the following pairs of ions is the first ion larger than the second ion? Responses H- , Li+ H+ , Li+ Mg+2 , Na+ Cl- , Br-
H- , Li+
Among the 4 compounds listed, the sequence that represents a decrease in polarity of the bond (largest to smallest) is Responses H-I, H-F, H-Br, H-Cl H-F, H-Cl, H-Br, H-I H-I, H-Br, H-Cl, H-F H-Cl, H-Br, H-I, H-F
H-F, H-Cl, H-Br, H-I
Which of the following gases have particles that would best follow the ideal gas law when observed at 0 degrees C and 1 atm? Responses H2 CO2 SO2 O2
H2
What is the conjugate base of H3PO4? Responses OH-1 PO4-3 H2PO4-1 HPO4-2 None of these
H2PO4-1
Which of the following molecules is NOT linear? Responses H2S C2H2 HCN BeCl2
H2S
Which of the following compounds has the most total sigma bonds? Responses H2CO H3COH CO CO2
H3COH
What is the conjugate acid of H2O? Responses H+1 OH-1 H3O+1 None of these
H3O+1
Phosphoric acid, H3PO4, is a weak acid. Which of the reactions below represent a reaction at equilibrium that would create a buffer solution? Responses H3PO4 <=> 3H+ + PO4-3 H3PO4 <=> 2H+ + HPO4-2 H3PO4 <=> H+ + H2PO4-1 None of these
H3PO4 <=> H+ + H2PO4-1
The experimental apparatus represented above is used to demonstrate the rates at which gases diffuse. When the cotton balls are placed in the ends of a tube at the same time, the gases diffuse from each end and meet somewhere in between, where they react to form a white solid. Which of the following combinations will produce a solid closest to the center of the tube? Responses HCl and CH3NH2 HCl and NH3 HBr and CH3NH2 HBr and NH3
HCl and CH3NH2
The hydrogen sulfate or bisulfate ion HSO4- is amphoteric and can act as an acid or a base in water solution. In which of the following equations does HSO4- act as a Brønsted-Lowry acid? Responses HSO4- + H2O → H2SO4 + OH- HSO4- + H3O+ → SO3 + 2H2O HSO4- + OH- → H2SO4 + O2- HSO4- + H2O → SO42- + H3O+ none of these
HSO4- + H2O → SO42- + H3O+
Which intermolecular force is responsible for the the high boiling point and surface tension of water? Responses Hydrogen bonds Dipole - Dipole London dispersion
Hydrogen bonds
Which of the following statement(s) are true for Halogens? I. Elements in this group are expected to form -1 anions. II. Elements in this group are expected to have large positive electron affinities. III. Elements in this group are nonmetals. Responses II and III III only I and III I only
I and III
Which of the following processes is/are endothermic? I. H2O(s) → H2O(g) II. CO2(g) → CO2(s) III. O2(g) → 2O(g) Responses I and II only II only I and III only III only
I and III only
Which of the following elements is the most active metal? Explain your choice using concepts from this unit. Include at least two reasons, and limit your explanation to the lines below. Elements: Mg, Ca, Sr, Ba
I think Barium would be the most active element because it will react easily due to its low ionization energy. All the other elements have a much higher ionization level meaning they would be less reactive
The substances bromine (Br2) and iodine monochloride (ICl) have almost identical molar masses yet ICl boils at 97ºC and Br2 boils at 59ºC. The best explanation for the difference in boiling points is Responses ICl has a stronger bond than that in Br 2 . ICl is a non-polar molecule and Br 2 is polar. ICl has a permanent dipole moment and Br 2 does not. ICl has a longer bond than that in Br2.
ICl has a permanent dipole moment and Br 2 does not.
Which of the following statements concerning chemical equilibrium is correct? I) Concentration of reactants = Concentration of products II) Rate of formation of reactants = Rate of formation of products III) The net concentration of reactants and products is constant. Responses I only I and II I, II, and III II and III II only
II and III
Water is added to a beaker containing a white crystalline solid. As the solid dissolves, the beaker becomes cold to the touch. Which of the following statements are TRUE? I) The reaction is exothermic. II) The reaction is endothermic. III) Heat energy is released by the system. IV) Heat energy is absorbed by the system. Responses I and IV II and IV II and III I and III
II and IV
Which of the following set of elements contains an element that does not belong to that group? I. Halogens: At, I, Br, F II. Transition elements: Cr, Ga, Os, Ni III. Inner transition elements: Ce, Lu, U, No Responses I only III only I and II only II only
II only
A sample of an ideal gas is cooled from 50.0oC to 25.0oC in a sealed container of constant volume. Which of the following values for the gas will decrease? I. The average molecular mass of the gas II. The average distance between the molecules III. The average speed of the molecules Responses I only II only III only I and III II and III
III only
The type of bonding involing the gain of one or more electrons by an atom is a(n) Responses reduction metallic bond ionic bond covalent bond coordinate covalent bond
Ionic bond
An atom has the following ionization energies (in kJ/mol) 1st: 802 2nd: 2,428 3rd: 3,667 4th: 23,906 Which of the following statements about the atom is true? Responses It has 3 valence electrons. It is a noble gas. It has 2 valence electrons. It is a halogen.
It has 3 valence electrons.
For an equilibrium established after the majority of the initial reactants have been converted to products, the Responses K<1 K=0 K= 1 K>1
K>1
central carbon is _____
Linear
CH4 has ___________________ as its only molecular force
London dispersion
Which of the following represents the expected radii of the series N, N+, N-, arranged in order of decreasing size? Responses N- > N > N+ N- > N+ > N N > N+ > N- N+ > N > N-
N- > N > N+
Among the following molecules of common gases, the one with the most shared electrons is Responses Cl2 H2 O2 N2
N2
Which of the following species has the largest dipole moment? Responses CO2 PO4-3 NF3 NO3-1
NF3
Which compound contains both ionic and covalent bonds? Responses NH4CN H2O OF2 MgF2
NH4CN
For which of the following compounds is resonance required to describe the structure adequately? Responses ClO4-1 CS2 NO2-1 Li2O none of these
NO2-1
____ is more reactive than Li and Mg but less than K
Na
Which among the following bonds is most ionic? Responses Br and Br H and Cl Na and F Na and O
Na and F
Which one of the following processes has a negative enthalpy change? Responses Na(g) → Na+(g) + e-1 NaCl(s) → Na+(g) + Cl-(g) Cl2(g) → 2Cl(g) Na(g) → Na(s)
Na(g) → Na(s)
London dispersion causes______
One non polar molecule to be attracted to another molecule
Which of the following atoms has the largest first ionization energy? Be careful on this one! Responses S Na P Mg K
P
Which pair of elements is most likely to form a covalently bonded compound? Responses Ca and S Zn and Br P and O Li and Cl
P and O
In which one of the following compounds do all the atoms obey the octet rule? (No exceptions or expanded octets.) Responses PCl5 PCl3 SF6 SF4
PCl3
The most active metal of the group containing Calcium is Responses Ca Sr Ba Ra
Ra
Increasing EN.
Rb<O<F
Out of SO2, SO3, and SO3^-2, which ones exhibit resonance
SO2, SO3
Element M is an Alkaline Earth Metal. Element M is more reactive than magnesium and has a smaller radius than barium. This element is: Responses Na K Sr Ra Be
Sr
Ammonia is prepared industrially by the Haber Process: N2(g) + 3H2(g) ↔ 2NH3(g) + 92.2 kJ K (at 25ºC) = 4.0 x 108 When the temperature of the reaction is increased to 500ºC, which of the following is TRUE? Responses The rate of the forward reaction will increase until equilibrium is reached again. At equilibrium, more NH3 is present at 500ºC than at 25ºC. K for the reaction will be larger at 500ºC than at 25ºC. None of the above is true. The concentration of N2 and H2 will increase
The concentration of N2 and H2 will increase
Nitric oxide, an important pollutant in air, is formed from the elements nitrogen and oxygen at high temperature, such as those obtained when gasoline burns in an automobile engine. At 2000ºC, K = 0.01 for the reaction: N2(g) + O2(g) ↔ 2 NO(g) Predict the direction in which the system will move to reach equilibrium if 0.4 moles of N2, 0.1 moles of O2, and 0.08 moles of NO are placed in a 1.0 liter container at 2000ºC. Responses The system remains unchanged. The concentration of NO will increase; the concentrations of N2 and O2 will decrease. More information is necessary. The concentration of NO will decrease; the concentrations of N2 and O2 will remain unchanged. The concentration of NO will decrease; the concentrations of N2 and O2 will increase.
The concentration of NO will decrease; the concentrations of N2 and O2 will increase.
A thick, clear liquid is poured onto a pile of purple crystals. Smoke is released, followed by a purple flame and intense heat. How does the energy of the reactants compare to the energy of the products? Responses The energy of the REACTANTS IS GREATER than the energy of the products. The energy of the PRODUCTS IS GREATER than the energy of the reactants. The energy of the reactants is exactly THE SAME as the energy of the products.
The energy of the REACTANTS IS GREATER than the energy of the products.
Which of the following statements concerning equilibrium is not true? Responses The value of the equilibrium constant for a given reaction mixture is the same regardless of the direction from which equilibrium is attained. Equilibrium in molecular systems is dynamic, with two opposing processes balancing one another. The equilibrium constant is independent of temperature. A system that is disturbed from an equilibrium condition responds in a manner to restore equilibrium. A system moves spontaneously toward a state of equilibrium.
The equilibrium constant is independent of temperature
Consider the combustion of methane (as represented by the following equation). This is the reaction that occurs for a Bunsen burner, which is a source of heat for chemical reactions in the laboratory. CH4(g) + 2 O2(g) ↔ CO2(g) + 2 H2O(g) For the system at equilibrium, which of the following explains what happens if the temperature is raised? Responses The equilibrium position is shifted to the left and the value for K increases. The equilibrium position is shifted to the right and the value for K decreases. The equilibrium position is shifted to the right and the value for K increases. The equilibrium position is shifted to the left and the value for K decreases. The equilibrium position is shifted but the value for K stays the same.
The equilibrium position is shifted to the left and the value for K decreases.
How is the height of Hg in a column of a Barometer used to measure the pressure of the atmosphere? Responses The higher the column in the tube (barometer) the lower the atmospheric pressure The lower the column in the tube (barometer) the higher the atmospheric pressure There is no relationship between the height of the Hg and the atmospheric pressure The higher the column in the tube (barometer) the higher the atmospheric pressure
The higher the column in the tube (barometer) the higher the atmospheric pressure
Which of the following statements is TRUE? Responses The atomic radius of Li is larger than that of Cs. The ionic radius of Fe+1 is larger than that of Fe+3. The first ionization energy of H is greater than that of He. The electron affinity of C is greater (more negative) than that of Cl. All the above statements are false.
The ionic radius of Fe+1 is larger than that of Fe+3.
When a sample of oxygen gas in a closed container of fixed volume is heated until its Kelvin temperature is doubled, which of the following is also doubled? Responses The density of the gas The pressure of the gas The average velocity of the gas molecules The number of molecules per cm3 The potential energy of the molecules
The pressure of the gas
The reaction A + B ↔ C + D has chemicals with the following colors: A and C are colorless B is red D is blue A solution begins with a red color, but as it is heated, the color changes from red to purple to blue. Which of the following is true of the equilibrium as written above? (hint: first determine which direction the equilibrium shifted) Responses The reaction is endothermic, with the "heat" term on the product side. The reaction is exothermic, with the "heat" term on the product side. The reaction is exothermic, with the "heat" term on the reactant side. The reaction is endothermic, with the "heat" term on the reactant side.
The reaction is endothermic, with the "heat" term on the reactant side.
Which of the following is NOT true for a solution at 25ºC that has a hydroxide (OH-) concentration of 1.0 x 10-10 M? Responses Kw = 1 x 10-14 The solution is acidic. The solution is basic. The [H+] is 1.0 x 10-4 M
The solution is basic.
Given the following equation: H2(g) + Cl2(g) → 2HCl(g) DH = -184.6 kJ which of the following statements is correct? Responses Energy is absorbed during the reaction. The enthalpy change represents the molar heat of formation of hydrogen chloride. The enthalpy change represents the energy released when H - Cl bonds are formed from hydrogen and chlorine atoms. The two hydrogen chloride molecules are at a lower enthalpy level than are the hydrogen and chlorine molecules.
The two hydrogen chloride molecules are at a lower enthalpy level than are the hydrogen and chlorine molecules.
A balloon filled with 0.25 mol of He(g) at 273 K and 1 atm is allowed to rise through the atmosphere. Which of the following explains what happens to the volume of the balloon as it rises from ground level to an altitude where the air temperature is 220 K and the air pressure is 0.1 atm? Responses The volume will increase because the decrease in air pressure will have a greater effect than the decrease in temperature. The volume will remain unchanged because of the counteracting effects of the decrease in temperature and the decrease in air pressure. The volume will decrease because the decrease in temperature will have a greater effect than the decrease in air pressure. It cannot be determined whether the volume of the balloon will increase, decrease, or remain the same without knowing the initial volume of the balloon.
The volume will increase because the decrease in air pressure will have a greater effect than the decrease in temperature.
The reaction quotient Q for a system is 720. If the equilibrium constant for the system is 36, what will happen as equilibrium is approached? Responses There will be a net gain in reactant. There will be a net gain in both product and reactant. There will be no net gain in either product or reactant. There will be a net gain in product.
There will be a net gain in reactant.
Which group of elements are characterized by the filling of d orbitals with their outermost electrons? Responses Transition metals Rare Earths Halogens Actinides
Transition metals
3 bonding neutrons, 1 lonely part is _________
Trigonal pyramidal 109 degrees
A bundle of metal washers at 100 oC were dropped into a calorimeter with water at 20 oC. The final temperature of the system was 24 oC. Assuming no heat was lost to or gained from the surroundings, the heat lost by the washers is equal to the heat gained by the water. Responses True False
True
Three elements X and Z have atomic numbers n and n+2 respectively. X readily forms stable ions X- and Z readily forms stable ions Z+. Which statement is correct based on the information provided? Responses X and Z belong to the same group of the Periodic Table. X has a lower ionization energy than Z. X will react readily with Z. X and Z are monatomic.
X will react readily with Z.
At low temperatures, the driving force that shows a spontaneous process is the change toward Responses a negative enthalpy state positive entropy negative entropy a positive enthalpy state
a negative enthalpy state
The chemical family that most readily forms cations with a unit (+1) charge is the Responses alkaline earth metals halogens alkali metals d-block metals
alkali metals
The element phosphorus exists in two forms in nature called white phosphorus and red phosphorus (like on the tip of the match). These two forms are examples of ____________. Responses noble gases isotopes allotropes metalloids oxidation
allotropes
In general, a change from a solid to a gas will proceed with Responses no change in energy a decrease in entropy no change in entropy an increase in entropy
an increase in entropy
Ions that are larger than the corresponding atoms are Responses anions cations positive metallic
anions
A solution with a [H+] = 1 x 10-13 is ____________. Responses acidic basic neutral Question cannot be answered from the data given.
basic
The molecular geometry around an oxygen atom in a molecule of water is best described as: Responses bent linear tetrahedral trigonal planar
bent
Water can act as _________________. Responses an acid a proton acceptor both A and B neither A nor B
both A and B
Least Polar.
br-br
Which of the following is not true of buffer solutions? Responses Acetic acid could be used to make a buffer solution strong acids will not make buffer solutions buffer solutions can maintain a constant pH when large amounts of acids or bases are added a mixture of a weak acid and its conjugate base
buffer solutions can maintain a constant pH when large amounts of acids or bases are added
The electron pair in a C - F bond could be considered Responses closer to C because carbon has a lower electronegativity than fluorine.. centrally located between the C and F. closer to F because fluorine has a higher electronegativity than carbon. an inadequate model since the bond is ionic. closer to C because carbon has a larger radius and thus exerts greater control over the shared electron pair.
closer to F because fluorine has a higher electronegativity than carbon.
A polyatomic ion, like CO3-2 is a charged group of atoms, bonded together largely by Responses metallic bonds ionic bonds covalent bonds nonpolar bonds
covalent bonds
Which of the following correctly lists these attractions in order of strength, starting with the WEAKEST? Responses dipole-dipole forces, hydrogen bond, covalent bond covalent bond, dipole-dipole forces, hydrogen bond covalent bond, dipole-dipole forces, ionic bond hydrogen bond, ionic bond, dipole-dipole forces
dipole-dipole forces, hydrogen bond, covalent bond
Consider the reaction: A(g) + B(g) ↔ C(g) + D(g). You have the gases A, B, C, and D at equilibrium. Upon adding the gas A and allowing equilibrium to be reestablished, the value of K: Responses increases, because by adding A, more products are made, increasing the product to reactant ratio. depends on whether the reaction is endothermic or exothermic. does not change, because A does not figure into the product to reactant ratio. decreases, because a is a reactant, so the product to reactant ratio decreases. does not change, as long as the temperature is constant.
does not change, as long as the temperature is constant.
The basis of the VSEPR model of molecular bonding is: Responses hybrid orbitals will form as necessary to, as closely as possible, achieve spherical symmetry regions of electron density in the valence shell of a central atom will arrange themselves so as to maximize overlap. electron regions on the central atom will organize themselves so as to maximize s orbital character. electron regions in the valence shell of a central atom will arrange themselves so as to minimize repulsions and be as far apart from each other as possible on the surface of the central atom
electron regions in the valence shell of a central atom will arrange themselves so as to minimize repulsions and be as far apart from each other as possible on the surface of the central atom
The greatest energy increase needed to remove successive electrons of the sodium atom occurs between the removal of the _________ and __________ electron Responses second and third third and fourth fourth and fifth first and second
first and second
For the equilibrium system: CO(g) + H2O(g) ↔ CO2(g) + H2(g) , an increase in pressure will Responses have no effect on the position of the equilibrium. increase the value of the equilibrium constant. shift the equilibrium to the left. shift the equilibrium to the right.
have no effect on the position of the equilibrium.
Endothermic processes like melting an ice cube may become spontaneous if the change in conditions results in TDS becoming greater that of DH. This becomes possible at Responses lower temperatures lower pressures higher pressures higher temperatures
higher temperature
Given the reaction: 2 SO2(g) + O2(g) ↔ 2 SO3(g) + 184 kJ The concentration of sulfur trioxide, SO3, may be INCREASED by Responses increasing the temperature of the system at constant pressure. increasing the pressure of the system at constant temperature. decreasing the pressure of the system at constant temperature. decreasing the concentration of oxygen. decreasing the concentration of sulfur dioxide.
increasing the pressure of the system at constant temperature.
The constant K is Responses dependent on both the initial concentrations and the temperature of the system. dependent on the initial concentrations and independent of the temperature of the system. independent of the initial concentrations and dependent on the temperature of the system. independent of the initial concentrations and the temperature of the system.
independent of the initial concentrations and dependent on the temperature of the system.
By definition, a weak acid _________________. Responses ionizes almost completely ionizes only slightly conducts poorly is a concentrated solution both A and D
ionizes only slightly
Metal atoms tend to ________ electrons and form positive ions
lose
Which of the following properties is characteristic of the alkali metals? Responses very high melting points relatively unreactive low first ionization energy smallest atomic radius in each period
low first ionization energy
Bonds with the highest degree of ionic character are formed between 2 elements having, as written in a formula, Responses low ionization energy and high electron affinity. low ionization energy and low electron affinity. high ionization energy and high electron affinity. high ionization energy and low electron affinity.
low ionization energy and high electron affinity.
Which of the following is not a property of a metal? Responses low melting point thermal conductivity ductility malleability electrical conductivity
low melting point
In general, the outer shell (energy level) electrons of nonmetals are ______________________compared to those of metals. Responses few in number and more strongly held few in number and more weakly held many in number and more strongly held many in number and more weakly held
many in number and more strongly held
Low electronegativity is characteristic of Responses metals gases nonmetals metalloids
metals
The properties of a system that drive the reaction to be spontaneous depend on the tendencies toward Responses positive enthalpy and negative entropy negative enthalpy and positive entropy positive enthalpy and positive entropy negative enthalpy and negative entropy
negative enthalpy and positive entropy
Gasoline will evaporate faster than water because gasoline is Responses polar and water is nonpolar. volatile and water is not. nonpolar and water is polar. less viscous than water. less dense than water.
nonpolar and water is polar.
A bond in which there is an equal attraction for the shared electrons by the bonded atoms is Responses nonpolar covalent coordinate covalent polar covalent ionic
nonpolar covalent
In periods 4,5, and 6 the sharp decrease in ionization energy between the last transition element and the next element in Group 13 (the group with Boron at the top) may be explained due to one electron being added to the ____ sublevel. Responses p d f s
p
Given the reaction: A + B ↔ C + D + heat The yield (amount produced) of substance D is INCREASED by Responses removing substance C. removing substance A. raising the temperature. removing substance B.
removing substance C.
For the hypothetical reaction A + B ↔ C + D, an increase in the concentration of D will Responses produce no shift. increase the value of the equilibrium constant. shift the equilibrium to the left. shift the equilibrium to the right.
shift the equilibrium to the left.
A solution in which the pOH is 6.3 would be described as Responses very acidic slightly acidic neutral very basic slightly basic
slightly basic
SiH2O2 is _________
tetrahedral
A molecule has 3 resonance structures, ... Responses the same atoms do not need to be bonded to each other in all resonance forms. there cannot be more than two resonance structures for a given species. the observed structure is an average of the resonance structures. one always corresponds to the observed structure.
the observed structure is an average of the resonance structures.
In a chemical change in which the forward reaction is barely underway when equilibrium is established, Responses considerable concentrations of both reactants and products are present at equilibrium. neither reaction is favored. the products of the reverse reaction are favored. the final products are favored.
the products of the reverse reaction are favored.
Which of the following are exactly equal for opposing reactions at chemical equilibrium? Responses pressure of reactant(s) and product(s) masses of reactant(s) and product(s) volume of reactant(s) and product(s) the rates of the forward and reverse reactions
the rates of the forward and reverse reactions
The highest electronegativities found in the Periodic Table are in the Responses lower left upper right upper left lower right
upper right
In general, atomic radii decrease Responses with an increase in the shielding of the nuclear charge. with an increase in the number of isotopes of an element. within a group (family) from low to high atomic number. within a period from low to high atomic number.
within a period from low to high atomic number
In the diatomic iodine molecule, each iodine atom has the electron arrangement (configuration) of the gas Responses oxygen xenon tellurium argon
xenon
Which of the following would most likely be classified as Arrhenius bases? Responses NH3 NaOH LiOH HNO3 A and D B and C
B and C