AP Chem Unit 4 Review
Which of the following best describes dissolving salt in water? a. The process is dissolution which is a chemical change. b. The particles of water and salt are not changed. c. The salt and water combine to form a new substance. d. The salt and water do not mix, so no change occurs.
B; The particles of water and salt are not changed.
Which of the following is an oxidation-reduction reaction that is also a synthesis reaction a. 2 Mg(s) + O2(g) → 2 MgO(s) b. Pb2+(aq) + CrO42-(aq) → PbCrO4(s) c. SO3(g) + 2 H2O(l) → H3O+(aq) + HSO4-(aq) d. 2 H2O(g) → 2 H2(g) + O2(g)
a. 2 Mg(s) + O2(g) → 2 MgO(s)
What is a half-reaction of this equation, Na + Cl → NaCl? a. Cl + e − → Cl− b. Cl + e− → Cl c. Na → Na + e− d. Na + Cl → Na+1Cl−1 13.
a. Cl + e- —> Cl-
Zn(s) is used to reduce other compounds in chemical reactions. If a chemist needs a substance that is more effective in its reducing ability, which of the following species would be the best choice? a. Na b. H+ c. K+ d. Cl-
a. Na
.Which of the following is the conjugate acid of NH2-? a. NH2- b. NH3 c. H+ d. NH4+
b. NH3
A 20.0 mL sample of 0.200 M K2CO3 solution is added to 30.0 mL of 0.400 M Ba(NO3)2 solution. Barium carbonate precipitates. The concentration of Ba2+ in solution after reaction is______ a. 0.150 M b. 0.160 M c. 0.200 M d. 0.240 M
c. 0.200 M
What is the conjugate base for HNO3? a. HN3 b. H2NO3 c. NO3+ d. NO3−
d. NO3-
Which of the following best describes a physical change? a. a change in which the particles in a material change arrangement. b. a change in which the particles in a material are transformed into different particles. c. a change in which scientists can observe happening in real time. d. a change in which the particles in a material are altered.
A; a change in which the particles in a material change arrrangment
A student mixes 20.0 g of white KCl crystals with distilled water in a beaker. After the mixture was stirred, no crystals are visible, and the solution is clear. After several days, all of the water evaporated, and white crystals are found in the beaker. Which of following pieces of experimental evidence would best help the student to confirm that a new compound had not been made and that only a physical change occurred? a. The solution does not change color after stirring. b. The KCl crystals are no longer visible after mixing with water. c. There is a temperature change in the solution during the dissolving process. d. After the water has evaporated, the white crystals in the beaker have a mass of 20.0 g.
D; After the water has evaporated, the white crystals in the beaker have a mass of 20.0 g.
In which species does sulfur have the lowest oxidation state? a. SCl2 b. OSF2 c. H2SO3 d. SF6
a. SCl2
The half-reactions for the oxidation-reduction reaction between Al(s) and Zn 2+(aq) are represented below. Al(s) → Al3+(aq) + 3e- Zn2+(aq) + 2e- → Zn(s) Based on the half-reactions, what is the coefficient for Al(s) if the equation for the oxidation-reduction reaction is balanced with the smallest whole-number coefficients? a. 1 b. 2 c. 3 d. 4
b. 2
How many electrons are transferred in the reaction represented by the balanced equation below? 2 MnO4- (aq) + 10 Br-(aq) + 16 H+(aq) → 2 Mn2+(aq) + 5 Br2(aq) + 8 H2O(l) a. 4 b. 5 c. 8 d. 10
b. 5
Gases W and X react in a closed, rigid vessel to form gases Y and Z according to the equation below. The initial pressure of W(g) is 1.20 atm and that of X(g) is 1.60 atm. No Y(g) or Z(g) is initially present. The experiment is carried out at constant temperature. W(g) + X(g) → Y(g) + Z(g) What is the partial pressure of Z(g) when the partial pressure of W(g) has decreased to 1.0 atm? a. 0.40 atm b. 0.20 atm c. 1.0 atm d. 1.2 atm
c. 1.0 atm
Which element is being reduced and how many electrons does it gain and/or lose? 2 Fe3+(aq) + Sn2+(aq) → 2 Fe2+(aq) + Sn4+(aq) a. Sn is reduced and loses 2 electrons. b. Sn is reduced and gains 2 electrons. c. Fe is reduced and gains 1 electron. d. Fe is reduced and loses 1 electron
c. Fe is reduced and gains 1 electron
A 100 mL sample of 0.1 M MgCl2(aq) and a 100 mL sample of 0.2 M NaOH(aq) were combined, and Mg(OH)2(s) precipitated, as shown by the equation below: MgCl2(aq) + 2 NaOH(aq) → 2 NaCl(aq) + Mg(OH)2(s) If the experiment is repeated using solutions of the same molarity, which of the following changes in volume will double the amount of Mg(OH)2(s) produced? a. Using the same volume of MgCl2(aq) but twice the volume of NaOH(aq). b. Using twice the volume of MgCl2(aq) but half the volume of NaOH(aq). c. Using twice the volume of MgCl2(aq) but the same volume of NaOH(aq). d. Using twice the volume of MgCl2(aq) and twice the volume of NaOH(aq).
c. Using twice the volume of MgCl2(aq) but the same volume of NaOH(aq)
A Bronsted-Lowry base is defined as a substance that _____. a. increases [H+] when placed in H2O b. decreases [OH−] when placed in H2O c. acts as a proton acceptor. d. acts as a proton donor.
c. acts as a proton acceptor
What is the oxidation number of Mo in MoO2Cl2? a. 0 b. +3 c. +5 d. +6
d. +6
For the dissolution of HCl in water represented below, which of the following pairs includes the Brønsted-Lowry bases? a. HCl (aq) and Cl−(aq) b. HCl(aq) and H3O+(aq) c. H2O( l) and H3O+(aq) d. H2O(l) and Cl−(aq)
d. H2O(l) and Cl−(aq)
Which of the following best represents a chemical change? a. Br 2(g) → Br2(l) b. KNO3 + NH4Cl → KCl + NH4NO3 c. AgNO3 + KCl → AgCl + KNO3 d. H2O(l) → H2O(g)
C; AgNO3 + KCl → AgCl + KNO3
The Brønsted-Lowry bases in the reaction represented below are NH3(aq) + HCl(aq) → NH4+(aq) + Cl−(aq) a. NH3(aq) and NH4+(aq) b. NH3(aq) and Cl−(aq) c. HCl(aq) and NH4+(aq) d. HCl(aq) and Cl−(aq)
b. NH3(aq) and Cl−(aq)
A student places a sample of a pure metal in a crucible and heats it strongly in air. Data from the experiment are given in the table below. Mass of empty crucible: 12.0 g Mass of crucible & sample before heating: 14.4 g Mass of crucible & sample after heating: 16.0 g The final mass was determined after the sample was cooled to room temperature. Which of the following statements related to the experiment is correct? a. The mass of the sample decreased, so physical changes occurred as the metal first melted and then boiled out of the crucible. b. The mass of the sample increased, so a chemical change occurred when bonds formed between the metal and another substance. c. There was nothing for the metal to react with, so only a physical change could have occurred. d. The sample was only heated, so neither a physical nor a chemical change occurred.
B; The mass of the sample increased, so a chemical change occurred when bonds formed between the metal and another substance.
A student was studying physical and chemical changes. The student carried out some procedures in the laboratory and recorded observations. For one of the procedures, the student concluded that a physical change took place, but not a chemical change. Which of the following could have been the results of the procedure? a. A cube of metal was changed into a flat sheet of metal. b. When two liquids at room temperature were combined in a beaker, the beaker became hot. c. When two clear liquids were combined, the resulting mixture was cloudy. d. When a colorless liquid was added to a blue liquid, the resulting solution was yellow.
a. A cube of metal was changed into a flat sheet of metal
Which of the following BEST describes what happens to C4H6 when a 5.00 g sample is heated from -10 C to 27 C? (see #14 on 10/3 dps for diagram) a. A physical change occurs when the liquid boils at 10.9 C, weakening the London dispersion forces between molecules. b. A physical change occurs when the liquid boils at 10.9 C, breaking the single and double bonds between C atoms in the molecule. c. A chemical change occurs when the liquid boils at 10.9 C, weakening the London dispersion forces between molecules. d. A chemical change occurs when the liquid boils at 10.9 C, breaking the single and double bonds between C atoms in the molecule.
a. A physical change occurs when the liquid boils at 10.9 C, weakening the London dispersion forces between molecules.
What is the difference between complete ionic equation and net ionic equation? a. Complete ionic equations include spectator ions while net ionic equations do not. b. Net ionic equations include spectator ions while complete ionic equations do not. c. Complete ionic equation includes compounds and spectator ions while net ionic equations do not. d. Net ionic equation includes compounds and spectator ions while complete ionic equations do not.
a. Complete ionic equations include spectator ions while net ionic equations do not.
Which of the following BEST describes the difference between the two equations shown below? Equation 1: H2O( l) → H2O(g) Equation 2: 2H2O(l) → 2H2(g) + O2(g) a. Equation 1 represents a physical change because intermolecular forces are broken during the process, whereas Equation 2 represents a chemical change because intramolecular forces are broken. b. Equation 1 represents a physical change because intramolecular forces are broken during the process, whereas Equation 2 represents a chemical change because intermolecular forces are broken. c. Equation 1 represents a chemical change because intermolecular forces are broken, and Equation 2 represents a physical change because intramolecular forces are broken. d. Equation 1 represents a chemical change because intramolecular forces are broken, and Equation 2 represents a physical change because intermolecular forces are broken.
a. Equation 1 represents a physical change because intermolecular forces are broken during the process, whereas Equation 2 represents a chemical change because intramolecular forces are broken.
When a student adds 30.0 mL of 1.00 M HCl to 0.56 g of powdered Fe, a reaction occurs according to the equation below. Fe(s) + 2 HCl(aq) → FeCl2(aq) + H2(g) When the reaction is complete at 273 K and 1.0 atm, which of the following is true? a. HCl is in excess, and 0.100 mol of HCl remains unreacted. b. HCl is in excess, and 0.020 mol of HCl remains unreacted. c. 0.015 mol of FeCl2 has been produced. d. 0.22 L of H2 has been produced.
a. HCl is in excess, and 0.100 mol of HCl remains unreacted.
In a titration experiment, H2O2(aq) reacts with aqueous MnO4-(aq) as represented by the equation below. 5 H2O2(aq) + 2 MnO4-(aq) + 6 H+(aq) → 2 Mn2+(aq) + 8 H2O2(aq) + 5 O2(g) The dark purple KMnO4 solution is added from a burette to a colorless, acidified solution of H2O2(aq) in an Erlenmeyer flask. (Note: At the end point of the titration, the solution is a pale pink color.) Which element is being oxidized during the titration, and what is the element's change in oxidation number? a. Oxygen, which changes from -1 to 0 b. Oxygen, which changes from 0 to -2 c. Manganese, which changes from -1 to +2 d. Manganese, which changes from +7 to +2
a. Oxygen, which changes from -1 to 0
Equal volumes of 0.2M solutions of lead(II) nitrate and potassium bromide are combined to form lead(II) bromide as a yellow precipitate. Which of the following is the correct net ionic equation for the reaction? a. Pb2+(aq) + 2 Br−(aq) → PbBr2(s) b. K+(aq) + NO3−(aq) → KNO3(aq) c. Pb2+(aq) + 2 NO3−(aq) + 2 K+(aq) + 2B r−(aq) → 2K+(aq) + 2 NO3−(aq) + PbBr2(s) d. Pb(NO3)2(aq) + 2KBr(aq) → PbBr2(s) + 2 KNO3(aq)
a. Pb2+(aq) + 2Br−(aq) → PbBr2(s)
The reaction between C6H12O6 and O2 is represented by the balanced equation below. In an experiment, 0.30 mol of CO2 was produced from the reaction of 0.05 mol of C6H12O6 with excess O2. C6H12O6(s) + 6 O2(g) → 6 CO2 (g) + 6 H2O(g) The reaction was repeated at the same temperature and in the same container, but this time 0.60 mol of CO2 was produced. Which of the following must be true? a. The initial amount of C6H12O6 b. Exactly 0.30 mol of C6H12O6 c. Exactly 0.40 mol of O2 must have reacted because the temperature and container volume are the same. d. More than 0.60 mol of O2 must have reacted because it was present in excess.
a. The initial amount of C6H12O6
According to the Arrhenius concept, an acid is a substance that _____. a. is capable of donating one or more H+ b. causes an increase in the concentration of H+ in aqueous solutions c. can accept a pair of electrons to form a coordinate covalent bond d. reacts with the solvent to form the cation formed by autoionization of that solvent
a. is capable of donating one or more H+
What is the percent yield of O2 if 12.3 g of KClO3 (molar mass 123 g) is decomposed to produce 3.2 g of O2 according to the equation below? 2 KClO3(s) → 2 KCl(s) + 3 O2(g) a. 100% b. 67% c. 50% d. 33%
b. 67%
The table below summarizes data given to a student to evaluate the type of change that took place when substance X was mixed with water. The student claimed that the data did not provide enough evidence to determine whether a chemical or physical change took place and that additional tests were needed. Water: clear cloudless liquid, 100 C BP, 1.00 g/mL density X: White crystalline solid, 1935.5 C BP, 2.15 g/mL Water + X: Clear colorless liquid, 101.6 C BP, 1.05 g/mL Which of the following identifies the best way to gather evidence to support the type of change that occurred when water and X were mixed? a. Measuring the melting point of the mixture of water and X. b. Adding another substance to the mixture of water and X to see whether a solid forms. c. Measuring and comparing the masses of the water, X, and the mixture of water and X. d. Measuring the electrical conductivities of X and the mixture of wat
b. Adding another substance to the mixture of water and X to see whether a solid forms.
A sample of a compound that contains only the elements C, H, and N is completely burned in O2 to produce 44.0 g of CO2, 45.0 g of H2O, and some NO2. A possible empirical formula of the compound is a. CH2N b. CH5N c. C2H5N d. C3H3N
b. CH5N
Which of the following describes the changes in forces of attraction that occur as H2O changes phase from a liquid to a vapor? a. H-O bonds break as H-H and O-O bonds form. b. Hydrogen bonds between H2O molecules are broken. c. Covalent bonds between H2O molecules are broken. d. Covalent bonds between H+ ions and H2O molecules become more effective.
b. Hydrogen bonds between H2O molecules are broken.
When 0.20 M NH4Cl(aq) and 0.20 M NaOH(aq) are mixed, the reaction represented by the equation below occurs and a strong smell of ammonia, NH3, is observed. NH4+(aq) + OH−(aq) → NH3(aq) + H2O(l) Based on this information, which of the following statements is true? a. NH4+(aq) acts as a Brønsted-Lowry base. b. NH4+(aq) is a stronger acid than H2O(l). c. NH3(aq) is a stronger base than OH−(aq). d. NH4+(aq) and Cl−(aq) are a conjugate acid-base pair
b. NH4+(aq) is a stronger acid than H2O(l).
The reaction between aqueous strontium chloride (SrCl2) and aqueous potassium sulfate (K2SO4) forms a precipitate of strontium sulfate (SrSO4). Which of the following represents the net ionic equation for the reaction? a. Cl−(aq) + K+(aq) → KCl(aq) b. Sr2+(aq) + SO42−(aq) → SrSO4(s) c. Sr2+(aq) + 2Cl−(aq) + SO42−(aq) + 2K+(aq) → SrSO4(s) + 2K+(aq) + 2Cl−(aq) d. SrCl2(aq) + K2SO4(aq) → SrSO4(s) + 2KCl(aq)
b. Sr2+(aq) + SO42−(aq) → SrSO4(s)
What is the net ionic equation of the reaction: SrBr2(aq) + K2SO4(aq) → SrSO4(s) + 2 KBr(aq)? a. Sr2+(aq) + 2 Br−(aq) + 2 K+(aq) + SO42−(aq) → SrSO4(s) + 2 K+(aq) + 2 Br−(aq) b. Sr2+(aq) + SO42−(aq) → SrSO4(s) c. Sr2+(aq) + Br−(aq) + 2 K+(aq) + SO42−(aq) → SrSO4(s) + 2 K+(aq) + Br−(aq) d. Br−(aq) + K+(aq) → KBr(aq)
b. Sr2+(aq) + SO42−(aq) → SrSO4(s)
A 2 mol sample of F2(g) reacts with excess NaOH(aq) according to the equation below. 2 F2(g) + 2 NaOH(aq) → OF2(g) + 2 NaF(aq) + H2O(l) If the reaction is repeated with excess NaOH(aq) but with 1 mol of F2(g) instead, which of the following is correct? a. The amount of OF2(g) produced is doubled. b. The amount of OF2(g) produced is halved. c. The amount of NaF(aq) produced remains the same. d. The amount of NaF(aq) produced remains the same.
b. The amount of OF2(g) produced is halved.
At 27°C, five identical rigid 2.0 L vessels are filled with N2(g) and sealed. Four of the five vessels also contain a 0.050 mol sample of NaHCO3(s), NaBr(s), Cu(s), or I2(s), as shown in the diagram below: (see 4.5 dps for diagram, #7) The volume taken up by the solids is negligible, and the initial pressure of N2(g) in each vessel is 720 mm Hg. All four vessels are heated to 127 °C and allowed to reach a constant pressure. At 127 °C, the entire sample of I2 is observed to have vaporized. How does the mass of vessel 5 at 127°compare to its mass at 27 °C? a. The mass is less, since the I2 is in the vapor phase. b. The mass is the same, since the number of each type of atom in the vessel is constant. c. The mass is greater, since the I2 will react with N2 to form NI3, which has a greater molar mass. d. The mass is greater, since the pressure is greater, and the particles have a higher average kinetic ene
b. The mass is the same, since the number of each type of atom in the vessel is constant.
A student pipetted five 25.00 mL samples of hydrochloric acid and transferred each sample to an Erlenmeyer flask, diluted it with distilled water, and added a few drops of phenolphthalein to each. Each sample was then titrated with a sodium hydroxide solution to the appearance of the first permanent faint pink color. The following results were obtained. Volumes of NaOH solution: 35.22 mL, 36.14 mL, 36.13 mL, 36.15 mL, and 36.12 mL Which of the following is the most probable explanation for the variation in the student's results? a. The burette was not rinsed with NaOH solution. b. The student misread a 5 for a 6 on the burette when the first sample was titrated. c. A different amount of water was added to the first sample. d. The pipette was not rinsed with the HCI solution. e. The student added too little indicator to the first sample.
b. The student misread a 5 for a 6 on the burette when the first sample was titrated.
When 100 mL of 1.0 M Na3PO4 is mixed with 100 mL of 1.0 M AgNO3, a yellow precipitate forms and [Ag+] becomes negligibly small. Which of the following is a correct listing of the ions remaining in solution in order of increasing concentration? a. [PO43-] < [NO3-] < [Na+] b. [PO43-] < [Na+] < [NO3-] c. [NO3-] < [PO43-] < [Na+] d. [Na+] < [NO3-] < [PO43-]
b. [PO43-] < [Na+] < [NO3-]
Potassium hydrogen phthalate, KHP, is used as a primary standard for determining the concentration of a solution of NaOH by titration. If the KHP has not been dried before weighing, the calculated molarity of the NaOH would be: a. higher than the actual value, since water is included in the apparent mass of KHP. b. higher than the actual value, since the presence of water requires a larger volume of titrant. c. lower than the actual value, since NaOH absorbs water. d. unaffected, since water is routinely added before the titration.
b. higher than the actual value, since the presence of water requires a larger volume of titrant.
Which of the following BEST describes what happens to C4H6 when a 5.00 g sample of C4H6 is mixed with a 10.00 g sample of C6H6 at -10.0 oC? a. A chemical change occurs, and the C4H6 forms nonpolar covalent bonds with the C6H6. b. A physical change occurs, and the C4H6 forms a thin, liquid layer above the liquid C6H6. c. A chemical change occurs as the C4H6 bonds are broken, and the individual C and H atoms are added to the C6H6 molecule to form C10H12. d. A physical change occurs as C4H6 forms London dispersion forces with C6H6 to create a mixture.
c. A chemical change occurs as the C4H6 bonds are broken, and the individual C and H atoms are added to the C6H6 molecule to form C10H12.
Use the following information to answer questions #1 & 2. In a titration experiment, H2O2(aq) reacts with aqueous MnO4-(aq) as represented by the equation below. The dark purple KMnO4 solution is added from a burette to a colorless, acidified solution of H2O2(aq) in an Erlenmeyer flask. (Note: At the end point of the titration, the solution is a pale pink color.) 5H2O2(aq) + 2 MnO4-(aq) + 6 H+(aq) → 2 Mn2+(aq) + 8 H2O2(aq) + 5 O2(g) Which of the following best describes what happens to the pH of the H2O2 solution as the titration proceeds? a. The +2 charge on the manganese ions maintains the acidity of the solution. b. The production of water dilutes the solution, making it basic. c. As H+ ions are consumed, the solution becomes less acidic and the pH increases. d. As H+ ions are consumed, the solution becomes less acidic and the pH decreases.
c. As H+ ions are consumed, the solution becomes less acidic and the pH increases.
If equal masses of the following compounds undergo complete combustion, which will yield the greatest mass of CO2? a. Benzene, C6H6 b. Cyclohexane, C6H12 c. Glucose, C6H12O6 d. Methane, CH4
c. Glucose, C6H12O6
When water is added to a mixture of Na 2O2(s) and S(s) , a redox reaction occurs, as represented by the equation below. 2 Na2O2(s) + S(s) + 2 H2O( l) → 4 NaOH(aq) + SO2(aq) Atoms of which element are reduced in the reaction? a. S - each atom loses four electrons b. Na in Na2O2 - each atom loses one electron c. O in Na2O2 - each atom gains one electron d. O in H2O - each atom gains one electron
c. O in Na2O2 - each atom gains one electron
The decomposition of H2O2(aq) is represented by the equation below. 2 H2O2(aq) → 2H2O(l) + O2(g) Which of the following identifies the element(s) being oxidized and reduced in the reaction? a. Hydrogen is oxidized and oxygen is reduced. b. Oxygen is oxidized and hydrogen is reduced. c. Oxygen is both oxidized and reduced. d. No elements are oxidized or reduced; the reaction is not a redox reaction.
c. Oxygen is both oxidized and reduced
When a burette is rinsed before a titration, which of the techniques below is the best procedure? a. Rinse the burette one time with some of the titrant solution. b. Rinse the burette one time with some of the titrant solution and then dry the burette in an oven. c. Rinse the burette two times: once with some of the titrant solution, then once with distilled water. d. Rinse the burette two times: each time with some of the titrant solution.
c. Rinse the burette two times: once with some of the titrant solution, then once with distilled water.
A student was asked to formulate a hypothesis about what would happen if 100.mL of 0.1M NaOH(aq) at 25°C was combined with 100.mL of 0.1M MgCl 2(aq) at 25°C. Which of the following hypotheses indicates that the student thought a chemical change would occur? a. The volume of the resulting solution will be equal to the sum of the volumes of the original solutions. b. The mass of the resulting solution will be equal to the sum of the masses of the original solutions. c. The resulting solution would contain a precipitate. d. The resulting solution will be clear.
c. The resulting solution would contain a precipitate.
Water is _____, which means that it can be an acid or a base depending on other reactants in reactions involving it. a. endothermic b. neutral c. amphoteric d. fixed
c. amphoteric
As base strength increases, conjugate acid strength _____. a. stays the same b. decreases, then increases c. increases d. decreases
c. increases
What is the complete ionic equation of the reaction: 2 AgNO3 (aq) + MgI2(aq) → 2 AgI(s) + Mg(NO3)2(aq)? a. Ag+(aq) + I−(aq) → AgI(s) b. 2 Ag+(aq) + 2 I−(aq) → 2 AgI(s) c. Ag+(aq) + NO3−(aq) + Mg2+(aq) + 2 I−(aq) → AgI(s) + Mg2+(aq) + NO3−(aq) d. 2 Ag+(aq) + 2 NO3−(aq) + Mg2+(aq) + 2 I−(aq) → 2AgI(s) + Mg2+(aq) + 2 NO3−(aq)
d. 2 Ag+(aq) + 2 NO3−(aq) + Mg2+(aq) + 2 I−(aq) → 2AgI(s) + Mg2+(aq) + 2 NO3−(aq)
Which of the following is the balanced net ionic equation for an oxidation-reduction reaction between Ag+(aq) and Ni(s) based on the half-reactions represented below? Ni(s) → Ni2+(aq) + 2e− Ag+(aq) + e− → Ag(s) a. Ag+(aq) + Ni(s) → Ag(s) + Ni2+(aq) b. 2 Ag+(aq) + Ni(s) → Ag(s) + 2 Ni2+(aq) c. Ag+(aq) + 2 Ni(s) → Ag(s) + 2 Ni2+(aq) d. 2 Ag+(aq) + Ni(s) → 2 Ag(s) + Ni2+(aq)
d. 2 Ag+(aq) + Ni(s) → 2 Ag(s) + Ni2+(aq)
At 27°C, five identical rigid 2.0 L vessels are filled with N2(g) and sealed. Four of the five vessels also contain a 0.050 mol sample of NaHCO3(s), NaBr(s), Cu(s), or I2(s), as shown in the diagram below. The volume taken up by the solids is negligible, and the initial pressure of N2(g) in each vessel is 720 mm Hg. All four vessels are heated to 127°C and allowed to reach a constant pressure. At 127°C, the pressure in vessel 1 is found to be higher than that in vessel 2. Which of the following reactions best accounts for the observation? a. NaHCO3(s) → Na(s) + HCO3(s) b. NaHCO3(s) → NaH(s) + CO3(s) c. 2 NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g) d. 2 NaHCO3(s) + N2(g) → 2 NaNO3(s) + C2H2(g)
d. 2 NaHCO3(s) + N2(g) → 2 NaNO3(s) + C2H2(g)
Equimolar samples of CH3OH( l) and C2H5OH(l) are placed in separate, previously evacuated, rigid 2.0 L vessels. Each vessel is attached to a pressure gauge, and the temperatures are kept at 300 K. In both vessels, liquid is observed to remain present at the bottom of the container at all times. The change in pressure inside the vessel containing CH3OH(l) is shown below. (see 10/3 DPS question #10 for diagram, i dont have quizlet plus) Which of the following best describes the change that takes place immediately after the CH3OH(l) is introduced into the previously evacuated vessel? a. A chemical change takes place because covalent bonds are broken. b. A chemical change takes place because intermolecular attractions are overcome. c. A physical change takes place because covalent bonds are broken. d. A physical change takes place because intermolecular attractions are overcome.
d. A physical change takes place because intermolecular attractions are overcome.
Which of the following compounds at 25°C and 1.0 atm contains an atom in a +1 oxidation state? a. CO2 b. CaO c. N2O5 d. Cu2O
d. Cu2O
What are the correct half-reactions of the given equation: Mn2+ + Fe → Mn + Fe3+ I. Mn2+ + 2 e- —> Mn II. Fe —> Fe3+ + 3 e- III. 2 Fe —> 2 Fe 3+ + 6 e- Hint: balance the equation first. a. I only b. II only c. III only d. I and II
d. I and II
When C2H4(g) reacts with H2(g), the compound C2H6(g) is produced, as represented by the equation opposite. The reaction is correctly classified as which of the following types? a. Acid-base, because two hydrogen atoms are donated to C2H4(g). b. Precipitation, because two reactant species form a single product. c. Decomposition, because pure H2(g) is consumed. d. Oxidation-reduction, because H2(g) is oxidized.
d. Oxidation-reduction, because H2(g) is oxidized.
The compound C6H8O6 reacts with I2 according to the reaction represented by the equation below. I2(aq) + C6H8O6(aq) → C6H6O6(aq) + 2I−(aq) + 2H+(aq) The reaction is correctly classified as which of the following types? a. Acid-base, because H+ ions are produced. b. Precipitation, because there are only two reactants but there are three products. c. Double replacement, because both H and I appear as ions in the products. d. Oxidation-reduction, because I is reduced.
d. Oxidation-reduction, because I is reduced
In which of the following species does sulfur have the same oxidation number as it does in H2SO4? a. H2SO3 b. S2O32- c. S2- d. SO2Cl2
d. SO2Cl
Which of the following is true regarding the reaction represented below? H2Se(g) + 4 O2F2(g) → SeF6(g) + 2 HF(g) + 4 O2(g) a. The oxidation number of O does not change. b. The oxidation number of H changes from -1 to +1. c. The oxidation number of F changes from +1 to -1. d. The oxidation number of Se changes from -2 to +6.
d. The oxidation number of Se changes from -2 to +6.
A student had two dilute, colorless solutions, HCl(aq) and NaOH(aq), which were at the same temperature. The student combined the solutions, and the reaction represented below occurred. HCl(aq) + NaOH(aq) → NaCl(aq) + H2O( l) Which of the following results would be evidence that a chemical reaction took place? a. The resulting solution is colorless. b. The temperature of the reaction mixture increases. c. The total volume of the mixture is approximately equal to the sum of the initial volumes. d. The resulting solution conducts electricity.
d. The resulting solution conducts electricity.
Which one of the following is a Bronsted-Lowry acid? a. (CH3)3NH+ b. CH3COOH c. HF d. all of the above
d. all of the above
The exothermic process represented below is best classified as a 2 H2O2(l) → 2 H2O(l) + O2(g) a. physical change because a new phase appears in the products. b. physical change because O2(g) that was dissolved comes out of solution. c. chemical change because entropy increases as the process proceeds. d. chemical change because covalent bonds are broken, and new covalent bonds are formed.
d. chemical change because covalent bonds are broken, and new covalent bonds are formed