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WorksheetsAP Chem Unit 4
Total questions: 40
Worksheet time: 41mins
2 H2O2(l) → 2 H2O(l) + O2(g)
The exothermic process represented above is best classified as a
physical change because a new phase appears in the products
physical change because O2(g) that was dissolved comes out of solution
chemical change because entropy increases as the process proceeds
chemical change because covalent bonds are broken and new covalent bonds are formed
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
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 above occurred. Which of the following results would be evidence that a chemical reaction took place?
The resulting solution is colorless.
The temperature of the reaction mixture increases.
The total volume of the mixture is approximately equal to the sum of the initial volumes.
The resulting solution conducts electricity.
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 MgCl2(aq) at 25°C. Which of the following hypotheses indicates that the student thought a chemical change would occur?
The volume of the resulting solution will be equal to the sum of the volumes of the original solutions.
The mass of the resulting solution will be equal to the sum of the masses of the original solutions.
The resulting solution would contain a precipitate.
The resulting solution will be clear.
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 cube of metal was changed into a flat sheet of metal.
When two liquids at room temperature were combined in a beaker, the beaker became hot.
When two clear liquids were combined, the resulting mixture was cloudy.
When a colorless liquid was added to a blue liquid, the resulting solution was yellow.
Which of the following is the balanced net-ionic equation for the reaction between Li(s) and water?
2 Li(s) + 2 H+(aq) + 2 OH−(aq) → 2 Li+(aq) + 2 OH−(aq) + H2(g)
2 Li(s) + 2 H2O(l) → 2 Li+(aq) + 2 OH−(aq) + H2(g)
2 Li(s) + 2 H2O(l) → 2 LiOH(s) + H2(g)
2 Li(s) + 2 H2O(l) → 2 LiH(s) + H2(g)
A 0.50g sample of Mg(s) was placed in a solution of HCl(aq), where it reacted completely.
Which of the following equations best represents the reacting species in the reaction described above?
Mg(s) + 2 H+(aq) → Mg2+(aq) + H2(g)
Mg(s) + HCl(aq) → MgCl2(aq) + H2(g)
Mg(s) + 2 HCl(aq) → MgCl2(s) + 2 H+(aq)
Mg(s) + 2 HCl(aq) → Mg2+(aq) + Cl2(g) + H2(g)
Which of the following is the net ionic equation for the reaction between aqueous sodium fluoride and hydrochloric acid?
NaF(aq) + HCl(aq) → NaCl(aq) + HF(aq)
Na+(aq) + F-(aq) + H+(aq) + Cl-(aq) → Na+(aq) + Cl-(aq) + HF(aq)
Na+(aq) + Cl-(aq) → NaCl(aq)
F-(aq) + H+(aq) → HF(aq)
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?
Pb2+(aq) + Br-(aq) → PbBr2(s)
K+(aq) + NO3-(aq) → KNO3(aq)
Pb2+(aq) + 2 NO3-(aq) + 2 K+(aq) + 2 Br-(aq) → 2 NO3-(aq) + 2 K+(aq) + PbBr2(s)
Pb(NO3)2(aq) + 2 KBr(aq) → PbBr2(s) + 2 KNO3(aq)
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?
Sr2+(aq) + SO4-(aq) → SrSO4(s)
K+(aq) + Cl-(aq) → KCl(aq)
Sr2+(aq) + 2 Cl-(aq) + 2 K+(aq) + SO4-(aq) → 2 Cl-(aq) + 2 K+(aq) + SrSO4(s)
SrCl2(aq) + K2SO4(aq) → SrSO4(s) + 2 KCl(aq)
A 20. mL sample of 0.50 M HC2H3O2(aq) is titrated with 0.50 M NaOH(aq). Which of the following best represents the species that react and the species produced in the reaction?
H+(aq) + OH−(aq) → H2O(l)
H+(aq) + C2H3O2−(aq) + Na+(aq) + OH−(aq) → H2O(l) + NaC2H3O2(aq)
HC2H3O2(aq) + OH-(aq) → C2H3O2-(aq) + H2O(l)
HC2H3O2(aq) + NaOH(aq) → H2O(I) + Na+(aq) + C2H3O2-(aq)
A student placed a piece of Zn(s) in a beaker containing CuSO4(aq). After 45 minutes, the student observed a brown solid at the bottom of the beaker and that the solution had turned from blue to colorless. Which of the following balanced equations best represents only the species that react and the species that are produced in the reaction?
A mixture of CO(g) and O2(g) is placed in a container, as shown above. A reaction occurs, forming CO2(g). Which of the following best represents the contents of the box after the reaction has proceeded as completely as possible?
Which of the following particle diagrams best represents the products when four molecules of H2O2(l) decompose into water and oxygen gas at room temperature?
The diagram above represents H2(g) and N2(g) in a closed container. Which of the following diagrams would represent the results if the reaction shown below were to proceed as far as possible?
N2(g) + 3 H2(g) → 2 NH3(g)
Which of the following particulate diagrams best shows the formation of water vapor from hydrogen gas and oxygen gas in a rigid container at 125oC?
Which of the following describes the changes in forces of attraction that occur as H2O changes phase from a liquid to a vapor?
H – O bonds break as H – H and O – O bonds form.
Hydrogen bonds between H2O molecules are broken.
Covalent bonds between H2O molecules are broken.
Ionic bonds between H+ ions and OH- ions are broken.
Covalent bonds between H+ ions and H2O molecules become more effective.
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 above. The final mass was determined after the sample was cooled to room temperature. Which of the following statements related to the experiment is correct?
The mass of the sample decreased, so physical changes occurred as the metal first melted and then boiled out of the crucible.
The mass of the sample increased, so a chemical change occurred when bonds formed between the metal and another substance.
There was nothing for the metal to react with, so only a physical change could have occurred.
The sample was only heated, so neither a physical nor a chemical change occurred.
A student mixes 20.0g 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 evaporates and white crystals are found in the beaker. Which of the 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?
The solution does not change color after stirring.
The KCl crystals are no longer visible after mixing with water.
There is a temperature change in the solution during the dissolving process.
After the water has evaporated, the white crystals in the beaker have a mass of 20.0g.
The table above 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. 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?
Measuring the melting point of the mixture of water and X
Adding another substance to the mixture of water and X to see whether a solid forms
Measuring and comparing the masses of the water, X, and the mixture of water and X
Measuring the electrical conductivities of X and the mixture of water and X
Fe(s) + 2 HCl(aq) → FeCl2(aq) + H2(g)
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 above. When the reaction is complete at 273 K and 1.0 atm, which of the following is true?
HCl is in excess, and 0.100 mol of HCl remains unreacted.
HCl is in excess, and 0.020 mol of HCl remains unreacted.
0.015 mol of FeCl2 has been produced.
0.22 L of H2 has been produced.
2F2(g) + 2 NaOH(aq) → OF2(g) + 2 NaF(aq) + H2O(l)
A 2mol sample of F2(g) reacts with excess NaOH(aq) according to the equation above. If the reaction is repeated with excess NaOH(aq) but with 1 mol of F2(g), which of the following is correct?
The amount of OF2(g) produced is doubled.
The amount of OF2(g) produced is halved.
The amount of NaF(aq) produced remains the same.
The amount of NaF(aq) produced is doubled.
MgCl2(aq) + 2 NaOH(aq) → 2 NaCl(aq) + Mg(OH)2(s)
A 100mL sample of 0.1M MgCl2(aq) and a 100mL sample of 0.2M NaOH(aq) were combined, and Mg(OH)2(s) precipitated, as shown by the equation above. 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?
Using the same volume of MgCl2(aq) but twice the volume of NaOH(aq)
Using twice the volume of MgCl2(aq) but half the volume of NaOH(aq)
Using twice the volume of MgCl2(aq) but the same volume of NaOH(aq)
Using twice the volume of MgCl2(aq) and twice the volume of NaOH(aq)
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
CH2N
CH5N
C2H5N
C3H3N2
2 SO2(g) + O2(g) → 2 SO3(g)
A mixture of gases containing 0.20 mol of SO2 and 0.20 mol of O2 in a 4.0 L flask reacts to form SO3. If the temperature is 25ºC, what is the pressure in the flask after reaction is complete?
40.4(0.082)(298)atm
40.3(0.082)(298)atm
40.2(0.082)(298)atm
40.2(0.082)(25)atm
40.3(0.082)(25)atm
Select a reaction in which the same reactant undergoes both oxidation and reduction
H2SeO4(aq) + 2 Cl-(aq) + 2 H+(aq) → H2SeO3(aq) + Cl2(g) + H2O(l)
S8(s) + 8 O2(g) → 8 SO2(g)
3 Br2(aq) + 6 OH-(aq) → 5 Br-(aq) + BrO3-(aq) + 3 H2O(l)
Ca2+(aq) + SO42-(aq) → CaSO4(s)
PtCl4(s) + 2 Cl-(aq) → PtCl62-(aq)
Select a precipitation reaction
2 Mg(s) + O2(g) → 2 MgO(s)
Pb2+(aq) + CrO42-(aq) → PbCrO4(s)
SO3(g) + 2 H2O(l) → H3O+(aq) + HSO4-(aq)
2 H2O(g) → 2 H2(g) + O2(g)
Ag+(aq) + 2 NH3(aq) → [Ag(NH3)2]+(aq)
The diagrams above represent solutes present in two different dilute aqueous solutions before they were mixed. Water molecules are not shown. When the solutions were combined, a precipitation reaction took place. Which of the diagrams below is the best particle representation of the mixture after the precipitation reaction occurred?
Which chemical or physical change occurs when aqueous solutions of ammonia and vinegar are mixed?
Oxidation-reduction reaction
Brønsted-Lowry acid-base reaction
Sublimation
Dehydration
Precipitation
Which chemical or physical change occurs when solid sodium acetate, NaC2H3O2(s), is added to water?
Oxidation-reduction reaction
Brønsted-Lowry acid-base reaction
Sublimation
Dehydration
Precipitation
Cu(s) + 4 HNO3(aq) → Cu(NO3)2(aq) + 2 NO2(g) + 2 H2O(l)
Which of the following is true about the reaction?
It is a Brønsted-Lowry acid-base reaction, because the solution is neutral at the end.
It is a Brønsted-Lowry acid-base reaction, because HNO3(aq) is a strong acid.
It is a redox reaction, because Cu(s) is oxidized and H+(aq) is reduced.
It is a redox reaction, because Cu(s) is oxidized and the nitrogen atom in NO3−(aq) is reduced.
Which of the following correctly identifies a Brønsted-Lowry conjugate acid-base pair in a solution prepared by mixing together HNO2(aq) and NH3(aq) ?
The acid is HNO2(aq), and the conjugate base is NH3(aq).
The acid is HNO2(aq), and the conjugate base is NO2−(aq).
The acid is NH4+(aq), and the conjugate base is NO2−(aq).
The acid is NH3(aq), and the conjugate base is NH4+(aq).
Which of the following is the conjugate acid of NH2- ?
NH2-
NH3
H+
NH4+
H2O
Which of the following is the conjugate base of HSO4-?
SO42-
HSO4-
H2SO4
OH-
H2O
The particle diagram above represents an aqueous solution of a weak monoprotic acid. The white circles represent H atoms. Which of the following shows the species that act as a Brønsted-Lowry base and its conjugate acid, in that order, in the solution?
Al(s) → Al3+(aq) + 3e−
Zn2+(aq) + 2e− → Zn(s)
The half-reactions for the oxidation-reduction reaction between Al(s) and Zn2+(aq) are represented above. 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?
1
2
3
4
Ni(s) → Ni2+(aq) + 2e−
Ag+(aq) + e− → Ag(s)
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 above?
Cu(s) + 2 AgNO3(aq) → Cu(NO3)2(aq) + 2 Ag(s)
The reaction between solid copper and aqueous silver nitrate produces solid silver and a blue solution, as represented by the balanced equation shown above. Based on the balanced equation, which of the following identifies the oxidation and reduction half-reactions?
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
higher than the actual value, since water is included in the apparent mass of KHP
higher than the actual value, since the presence of water requires a larger volume of titrant
lower than the actual value, since NaOH absorbs water
unaffected, since KHP is a strong acid
unaffected, since water is routinely added before the titration
When a buret is rinsed before a titration, which of the techniques below is the best procedure?
Rinse the buret one time with some of the titrant solution.
Rinse the buret one time with some of the titrant solution and then dry the buret in an oven.
Rinse the buret two times: once with some of the titrant solution, then once with distilled water.
Rinse the buret two times: each time with some of the titrant solution.
Rinse the buret two times: each time with distilled water.
A student pipetted five 25.00–milliliter 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
First Sample.....35.22 mL
Second Sample.....36.14 mL
Third Sample.....36.13 mL
Fourth Sample .....36.15 mL
Fifth Sample.....36.12 mL
Which of the following is the most probable explanation for the variation in the student’s results?
The burette was not rinsed with NaOH solution.
The student misread a 5 for a 6 on the burette when the first sample was titrated.
A different amount of water was added to the first sample.
The pipette was not rinsed with the HCI solution.
The student added too little indicator to the first sample.
