Unit 4 Chemistry
According to the balanced equation above, how many moles of ClO2- are needed to react completely with 20 mL of 0.20 M KMnO4 solution?
0.0030 mol
Permanganate and oxalate ions react in an acidified solution according to the balanced equation above. How many moles of CO2 are produced when 20 mL of acidified 0.20 M KMnO4 solution is added to 50 mL of 0.10 M Na2C2O4 solution?
0.010 mol
When the equation above is balanced and all coefficients are reduced to their lowest whole-number terms, what is the coefficient of H20?
2
In the reaction presented above, what is the total number of moles of reactants consumed when 1.00 mole of CO2 is produced?
2.00 mol
According to the equation above, how many moles of potassium chlorate KClO2 must be decomposed to generate 1.0 L of O2 gas at standard temperature and pressure?
2/3 (1/22.4) mol
In the reaction represented above, what mass of HF is produced by the reaction of 3.0x10^23 molecules of H2 with excess F2?
20 g
A 6.0 mol sample of C3H8 and a 20 mol sample of Cl2 are placed in a previously evacuated vessel, whether they react according to the equation above. After one of the reactants has been totally consumed, how many moles of HCI have been produced.
20 mol
Which of the following is the balanced net ionic equation for an oxidation-reduction reaction between Ag+ and Ni based on the half reactions represented above?
2Ag+ + Ni -> 2Ag + Ni2+
Which of the following is an oxidation-reduction reaction that is also a synthesis reaction?
2Mg + O2 -> 2MgO
At 127 degrees Celcius, 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?
2NaHCO3-> Na2CO +CO2+H2O
The total pressure in the flask measured at 400 K is closest to which of the following?
3 atm
When the equation above is balanced and all coefficients are reduced to their lowest whole-number terms, what is the coefficient for H3PO4?
4
Which of the following best represents the container after the reaction has gone to completion?
4 OH and 2 O2
When 8 g of N2H4 (32 g mol -1) and 92 g of N2O4 (92 g mol -1) are mixed together and react according to the equation above, what is the maximum mass of H2O that can be produced?
9,0. g
According to the reaction represented above, about how many grams of aluminum (atomic mass 27 g ) are necessary to produce 0.50 mol of hydrogen gas at 25 degrees and 1.00 atm?
9.0 g
Which of the following could have been the results of the procedure?
A cube of metal was changed into a flat sheet of metal
Which of the following best describes the change that takes place immediately after the CH4OH is introduced into the previously evacuated vessel
A physical change takes place because intermolecular attractions are overcome
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?
After the water has evaporated, the white crystals in the beaker have a mass of 20.0g.
Which of the following best describes what happens to the pH of the H2O2 solution as the titration proceeds?
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?
Benzene, C6H6
Which of the following diagrams would best represent the results if the reaction shown below were to proceed as far as possible?
Box with 2 NH3 and 2 N2
Which of the following best represents the contents of the box after the reaction has proceeded as completely as possible?
Box with 3 CO2 and 1 O2
Which of the following particle diagrams best represents the products when four molecules of H20 decompose into water and oxygen gas at room temperature?
Box with 3 OH and 2 O2
A sample of a compound that contains only the elements C, H, and N is completely burned in )2 to produce 44.0 g of CO2, 45 g H20, and some NO2. A possible empirical formula of the compound is
CH5N
Which is the balanced equation for the dissolution of Ca(OH) in pure water?
Ca(OH)2 -> Ca2+ +2OH-
Which of the following compounds at 25 degrees and 1 atm contains an atom in a +1 oxidation state?
Cu2O
Which of the following is the net ionic equation for the reaction between aqueous sodium fluoride and hydrochloric acid?
F- +H+ ->HF
For the dissolution of HCI in water represented above, which of the following pairs includes the bronsted-lowry bases?
H2O and Cl-
All of the reactions represented above occur in an aqueous solution of oxalic acid. Which of the following represent a bronsted-lowry conjugate acid-base pair?
HC2O4- and C2O42-
Which of the following describes the changes in forces of attraction that occur as H20 changes phase from a liquid to a vapor?
Hydrogen bonds between H20 molecules are broken
In the equilibrium represented above, the species that act as bases include which of the following?
II and III only
What is the identity of the metal chloride?
KCl
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 electrical conductivities of X and the mixture fo water and X
Which of the following is the conjugate acid of NH2-?
NH3
The Bronsted-Lowry bases in the reaction represented above are
NH3 and Cl-
When 0.2 M NH4Cl and 0.2 M NaOH are mixed, the reaction represented by the equation above occurs and a strong smell of ammonia, NH3, is observed. Based on this information, which of the following statements is true?
NH4+ is a stronger acid than H2O is
Which of the following represents a process in which a species is reduced?
NO3- -> NO(g)
Zn 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?
Na
Atoms of which element are reduced in the reaction?
O in Na2O2-each atom gains 1 electron
In the reaction presented above, the number of MnO4- ions that react must be equal to which of the following?
One-fifth the number of Fe2+ ions that are consumed
Based on the balanced equation, which of the following identifies the oxidation and reduction half reactions?
Oxidation Half Reaction= Cu -> Cu2+ + 2 e- Reduction Half Reaction= Ag+ +e- -> Ag
The reaction is correctly classified as which of the following types?
Oxidation-reduction, because H2 is oxidized
The compound C6H8O6 reacts with I2 according to the reaction presented by the equation above. The reaction is correctly classified as which of the following types?
Oxidation-reduction, because I2 is reduced
The decomposition of H2O is represented by the equation above. Which of the following identifies the element being oxidized and reduced in the same reaction?
Oxygen is both oxidized and reduced
Which element is being oxidized during the titration, and what is the element's change in oxidation number?
Oxygen, which changes from -1 to 0
Which of the following is a precipitation reaction?
Pb2+ +CrO4^2- -> PbCrO
In which of the following species does sulfur have the same oxidation number as it does in H2SO4?
SO2Cl2
The reaction between aqueous strontium chloride and aqueous potassium sulfate forms a precipitate of strontium sulfate. Which of the following represents the net ionic equation for the reaction?
Sr2+ +SO42- -> SrSO
Which of the following particulate diagrams best shows the formation of water vapor from hydrogen gas and oxygen gas in a rigid container at 125 degrees celcius?
Starting box has 3 O2 and 6 H2
If the reaction is repeated with excess NaOH but with 1 mol of F2, which of the following is correct?
The amount of OF2 produced is halved.
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?
The initial amount of C6H12O6 in the container must have been 0.10 mol
At 127 degrees, the entire sample of I2 is observed to have vaporized. How does the mass of vessel 5 at 127 degrees compare to its mass at 27 degrees?
The mass is the same, since the number of each type of atom in the vessel is constant
Which of the following statements related to the experiment is correct?
The mass of the sample increased, so a chemical change occurred when bonds formed between the metal and another substance
Which of the following shows the species that act as a bronsted-lowry base and its conjugate acid, in that order, in the solution?
The one with 1 H2O and 1 H3O
Which of the following particle views best represents the mixture when the titration is halfway to the equivalence point?
The one with 5 H2O2 and 2 Mn2+
Which of the following is true regarding the reaction represented above?
The oxidation number of Se changes from -2 to +6
Which of the following is the most probable explanation for the variation in the student's results?
The pipette was not rinsed with the HCI solution
Which of the following hypotheses indicates that the student thought a chemical change would occur?
The resulting solution would contain a precipitate
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 temperature of the reaction mixture increases
If the experiment is repeated using solutions of the same molarity, which of the following changes in volume will double the amount of MgOH2 produced?
Using twice the volume of MgCl2 and twice the volume of NaOH
When 100 mL of 1.0 M Na3PO4 is mixed with 100 mL of 1.0 M AgNO3, a yellow precipitate forms [Ag+] becomes negligibly small. Which of the following is a correct listing of the ions remaining in solution in order of increasing concentration?
[PO4^3-]<[NO3-]<[Na+]
The exothermic process represented above is best classified as a
chemical change because covalent bonds are broken and new covalent bonds are formed
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 NaOH will be
higher than the actual value, since water is included in the apparent mass of KHP
If the reaction of silver metal and dilute nitric acid proceeds according to the equation above. If 0.10 mole of powdered silver is added to 10 mL of 6- molar nitric acid, the number of moles of NO gas that can be formed is
0.015 mol
Reaction 2 occurs when an excess of 6 M HCI solution is added to 1.0 mL of NaOCL of unknown concentration. If the reaction foes to completion and 0.010 mol of Cl2 is produced, then what was the molarity of the NaOCL solution?
0.10 M
The 20.0 milliliter sample of 0.200 molar K2CO3 solution is added to 30.0 milliliters of 0.400 molar Br(NO3)2 solution. Barium carbonate precipitates. The concentration of barium ion, Ba2+ in solution after reaction is
0.160 M
What is the partial pressure of Z when the partial pressure of W has decreased to 1.0 atm?
0.20 atm
If 0.40 mol of H2 and 0.15 mol of O2, were to react as completely as possible to produce H2O, what mass of reactant would remain?
0.20 g of H2
What is the maximum number of moles of Al2O3 that can be produced by the reaction of 0.40 mol of Al with 0.40 mol of O2?
0.20 mol
When the reaction is complete at 273 K and 1.0 atm, which of the following is true?
0.22 L of H2 has been produced
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 25 degrees, what is the pressure in the flask after reaction is complete?
0.3(0.082)(298)/4 atm
A 1.0 L sample of an aqueous solution contains 0.10 mol of NaCl and a 0.10 mol of CaCl2. What is the minimum number of moles of AgNO3 that must be added to the solution in order to precipitate all of the Cl and AgCl(s)?
0.30 mol
How many electrons are transferred in the reaction represented by the balanced equation above?
10
When the equation above is balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O2 is
12
What volume of O2 is required to react with excess CS2 to produce 4.0 L of CO2?
12 L
What mass of Au is produced when 0.0500 mol of Au2S3 is reduced completely with excess H2?
19.7 g
The half-reactions for the oxidation-reduction reaction between Al and Zn2+ are represented above. Based of the half-reactions, what is the coefficient for Al if the equation for the oxidation-reduction reaction is balanced with the smallest whole number coefficients?
2
According to the balanced equation above, how many moles of HI would be necessary to produce 2.5 mol of I2 starting with 4 mol of KMnO4, and 3 mol of H2SO4?
5.0
What is the percentage yield of O2 if 12.3 g of KClO (molar mass 123 g) is decomposed to produce 3.2 g O2 (molar mass 32 g) according to the equation above?
67%
Which is the net ionic equation for the reaction that occurs to cause the solution to be basic?
F+ +H2O -> HF + OH-
Equal volumes of 0.2M solutions of lead nitrate and potassium bromide are combined to form lead bromide as a yellow precipitate. Which of the following is the correct net ionic equation for the reaction?
Pb2+ +2Br- ->PbBr
When a buret is rinsed before a titration, which of the techniques below is the best procedure?
Rinse the buret two times: each time with some of the titrant solution.