Questions and Answers of Chemistry An Atoms First Approach

All the Group 1A (1) and 2A (2) metals are produced by electrolysis of molten salts. Why? Group 1A (1) Elements (Alkali Metals) > Have valence configuration ¹ > Except for hydrogen, readily lose one
The rate constant for a certain radioactive nuclide is 1.0 × 10-3 h-1. What is the half-life of this nuclide?
The Group 5A (15) elements can form molecules or ions that involve three, five, or six covalent bonds; NH3, AsCl5, and PF6- are examples. Draw the Lewis structure for each of these substances, and
Assign oxidation numbers to all the atoms in each of the following: a. HNO3 b. CuCl₂ c. 0₂ d. H₂O₂ e. C6H12O6 f. Ag g. PbSO4 h. PbO₂ i. Na₂C₂O4 j. CO₂ k. (NH4)2Ce(SO4)3 1. Cr₂03
In the electrolysis of an aqueous solution of Na2SO4, what reactions occur at the anode and the cathode (assuming standard conditions)? 2- S₂0² +2e 250 O₂ + 4H+ + 4e →→→ 2H₂O 2H₂O +
Gold is produced electrochemically from an aqueous solution of Au(CN)2- containing an excess of CN-. Gold metal and oxygen gas are produced at the electrodes. What amount (moles) of O2 will be
Fig. 18.1 illustrates the zone of stability. What is the zone of stability? Stable light nuclides have about equal numbers of neutrons and protons. What happens to the neutron-to-proton ratio for
An aqueous solution of PdCl2 is electrolyzed for 48.6 seconds, and during this time 0.1064 g of Pd is deposited on the cathode. What is the average current used in the electrolysis?
Uranium-235 undergoes a series of α-particle and β-particle productions to end up as lead-207. How many α particles and β particles are produced in the complete decay series?
When using a Geiger–Müller counter to measure radioactivity, it is necessary to maintain the same geometrical orientation between the sample and the Geiger–Müller tube to compare different
To determine the Ksp value of Hg2I2, a chemist obtained a solid sample of Hg2I2 in which some of the iodine is present as radioactive 131I. The count rate of the Hg2I2 sample is 5.0 × 1011 counts
Which do you think would be the greater health hazard: the release of a radioactive nuclide of Sr or a radioactive nuclide of Xe into the environment? Assume the amount of radioactivity is the same
How do the acidities of the aqueous solutions of the alkaline earth metal ions (M2+) change in going down the group?
Silicon carbide (SiC) is an extremely hard substance. Propose a structure for SiC.
Boron hydrides were once evaluated for possible use as rocket fuels. Complete and balance the following equation for the combustion of diborane. B₂H6(g) + O₂(g) →→→→ B(OH)3(s)
One harmful effect of acid rain is the deterioration of structures and statues made of marble or limestone, both of which are essentially calcium carbonate. The reaction of calcium carbonate with
The xerographic (dry writing) process was invented in 1938 by C. Carlson. In xerography, an image is produced on a photoconductor by exposing it to light. Selenium is commonly used, since its
What are three-centered bonds?
Give the Lewis structure, molecular structure, and hybridization of the oxygen atom for OF2. Would you expect OF2 to be a strong oxidizing agent like O2F2 discussed in Exercise 61?Exercise 61.Write
Hydrazine (N2H4) is used as a fuel in liquid-fueled rockets. When hydrazine reacts with oxygen gas, nitrogen gas and water vapor are produced. Write a balanced equation and use bond energies from
Although nitrogen trifluoride (NF3) is a thermally stable compound, nitrogen triiodide (NI3) is known to be a highly explosive material. NI3 can be synthesized according to the equationa. What is the
Suppose 10.00 g of an alkaline earth metal reacts with 10.0 L water to produce 6.10 L hydrogen gas at 1.00 atm and 25°C. Identify the metal and determine the pH of the solution.
A cylinder fitted with a movable piston initially contains 2.00 moles of O2(g) and an unknown amount of SO2(g). The oxygen is known to be in excess. The density of the mixture is 0.8000 g/L at some T
What is the major focus of the crystal field model? Why are the d orbitals split into two sets for an octahedral complex? What are the two sets of orbitals?Define each of the following. a.
Why do tetrahedral complex ions have a different crystal field diagram than octahedral complex ions? What is the tetrahedral crystal field diagram? Why are virtually all tetrahedral complex ions
Review Table 20.18, which lists some important biological functions associated with different first-row transition metals. The transport of O2 in the blood is carried out by hemoglobin. Briefly
Define and give an example of each of the following. a. Roasting b. Smelting c. Flotation d. Leaching e. GangueWhat are the advantages and disadvantages of hydrometallurgy? Describe the process
CoCl42- forms a tetrahedral complex ion and Co(CN)63- forms an octahedral complex ion. What is wrong about the following statements concerning each complex ion and the d orbital splitting diagrams?a.
Kevlar, used in bulletproof vests, is made by the condensation copolymerization of the monomers Draw the structure of a portion of the Kevlar chain. H₂N- O -NH₂ and HO₂C CO₂H
Which of the following conditions indicate a basic solution at 25°C? a. pOH = 11.21 b. pH = 9.42 c. [OH-]> [H+] d. [OH-]> 1.0 × 10-7 M
One mechanism for the destruction of ozone in the upper atmosphere is a. Which species is a catalyst? b. Which species is an intermediate? c. Ea for the uncatalyzed reactionIs 14.0 kJ. Ea for the
A first-order reaction has rate constants of 4.6 × 10-2 s-1 and 8.1 × 10-2 s-1 at 0°C and 20.°C, respectively. What is the value of the activation energy?
Sulfuryl chloride undergoes first-order decomposition at 320.°C with a half-life of 8.75 h.What is the value of the rate constant, k, in s-1 ? If the initial pressure of SO2Cl2 is 791 torr and the
A popular chemical demonstration is the “magic genie” procedure, in which hydrogen peroxide decomposes to water and oxygen gas with the aid of a catalyst. The activation energy of this
Upon dissolving InCl(s) in HCl, In+(aq) undergoes a disproportionation reaction according to the following unbalanced equation:This disproportionation follows first-order kinetics with a half-life of
Characterize a system at chemical equilibrium with respect to each of the following: a. The rates of the forward and reverse reactions b. The overall composition of the reaction mixtureFor a
For a typical equilibrium problem, the value of K and the initial reaction conditions are given for a specific reaction, and you are asked to calculate the equilibrium concentrations. Many of these
Write the equilibrium expression (K) for each of the following gas-phase reactions. a. N₂(g) + O₂(g)=2NO(g) b. N₂O₂(g)2NO₂(g) c. SiH4(g) + 2Cl₂(g) d. 2PBr3(g) + 3Cl₂(g) SiCl4(g) +
Consider the following reaction at a certain temperature: An equilibrium mixture contains 1.0 mole of Fe, 1.0 × 10-3 mole of O2, and 2.0 moles of Fe2O3 all in a 2.0-L container. Calculate the value
At a particular temperature, K = 1.00 × 102 for the reactionIn an experiment, 1.00 mole of H2, 1.00 mole of I2, and 1.00 mole of HI are introduced into a 1.00-L container. Calculate the
Given the following equilibrium constants at 427°C,Determine the values for the equilibrium constants for the following reactions: 2Na(1) + O₂(g) Na₂O(s) NaO(g) Na(1) + O₂(g) Na₂O₂
For the reaction: K = 1.8 × 10-7 at a certain temperature. If at equilibrium [O2] = 0.062 M, calculate the equilibrium O3 concentration. 30₂(g) 203(g)
At 35°C, K = 1.6 × 10-5 for the reactionIf 2.0 moles of NO and 1.0 mole of Cl2 are placed into a 1.0-L flask, calculate the equilibrium concentrations of all species. 2NOCI(g)2NO(g) + Cl₂(g)
How is acid strength related to the value of Ka? What is the difference between strong acids and weak acids (see Table 13.1)? As the strength of an acid increases, what happens to the strength of the
Define or illustrate the meaning of the following terms: a. Amphoteric b. Kw reaction c. Kw equilibrium constant d. pH e. pOH f. pKwGive the conditions for a neutral aqueous solution at 25°C,
Two strategies are followed when solving for the pH of an acid in water. What is the strategy for calculating the pH of a strong acid in water? What major assumptions are made when solving strong
Which of the following conditions indicate an acidic solution at 25°C? a. pH = 3.04 b. [H]> 1.0 × 10-7 M c. pOH = 4.51 d. [OH-] 3.21 × 10-¹² M
Why is H3O+ the strongest acid and OH- the strongest base that can exist in significant amounts in aqueous solutions?
How many significant figures are there in the following numbers: 10.78, 6.78, 0.78? If these were pH values, to how many significant figures can you express the [H+]? Explain any discrepancies
For each of the following aqueous reactions, identify the acid, the base, the conjugate base, and the conjugate acid. 3+ a. Al(H₂O) ³+ + H₂O—H₂0* + Al(H₂O),(OH)²+ b. H₂O + HONH3 +
The pH of a sample of gastric juice in a person’s stomach is 2.1. Calculate the pOH, [H+], and [OH-] for this sample. Is gastric juice acidic or basic?
Calculate the pH of a 5.0 × 10-3 -M solution of H2SO4.
The Kb values for ammonia and methylamine are 1.8 × 10-5 and 4.4 × 10-4 , respectively. Which is the stronger acid, NH4+ or CH3NH3+?
Are solutions of the following salts acidic, basic, or neutral? For those that are not neutral, write balanced equations for the reactions causing the solution to be acidic or basic. The relevant Ka
Consider a solution of an unknown salt having the general formula BHCl, where B is one of the weak bases in Table 13.3. A 0.10-M solution of the unknown salt has a pH of 5.82. What is the actual
Calculate the pH of each of the following solutions. a. 0.12 M KNO2 b. 0.45 M NaOClc. 0.40 M NH4ClO4
Calculate the pH of the following solutions: a. 1.2 M CaBr₂ b. 0.84 M C6H5NH3NO3 (K₁ for C6H5NH₂ = 3.8 × 10-¹⁰) c. 0.57 M KC₂H5O₂ (K₁ for HC-H₂O₂ = 6.4 x 10-5)
Students are often surprised to learn that organic acids, such as acetic acid, contain OOH groups. Actually, all oxyacids contain hydroxyl groups. Sulfuric acid, usually written as H2SO4, has the
The pH of 1.0 × 10-8 M hydrochloric acid is not 8.00. The correct pH can be calculated by considering the relationship between the molarities of the three principal ions in the solution (H+, Cl-,
Consider the species PO43-, HPO42-, and H2PO4-. Each ion can act as a base in water. Determine the Kb value for each of these species. Which species is the strongest base?
a. The principal equilibrium in a solution of NaHCO3 isCalculate the value of the equilibrium constant for this reaction. b. At equilibrium, what is the relationship between [H2CO3] and [CO32-]? c.
Calculate the pH of a 0.10-M solution of sodium phosphate. (See Exercise 183.)Data in Exercise 183Consider the species PO43-, HPO42-, and H2PO4-. Each ion can act as a base in water. Determine the Kb
For the following, mix equal volumes of one solution from Group I with one solution from Group II to achieve the indicated pH. Calculate the pH of each solution. a. The solution with the lowest
A 0.100-g sample of the weak acid HA (molar mass = 100.0 g/mol) is dissolved in 500.0 g water. The freezing point of the resulting solution is -0.0056°C. Calculate the value of Ka for this acid.
A friend asks the following: “Consider a buffered solution made up of the weak acid HA and its salt NaA. If a strong base like NaOH is added, the HA reacts with the OH- to form A-. Thus the amount
Could a buffered solution be made by mixing aqueous solutions of HCl and NaOH? Explain. Why isn’t a mixture of a strong acid and its conjugate base considered a buffered solution?
Instead of the titration of a strong acid by a strong base considered in Question 5, consider the titration of a strong base by a strong acid. Compare and contrast a strong acid–strong base
Calculate the pH of a solution that is 1.00 M HNO2 and 1.00 M NaNO2.
Calculate the pH after 0.10 mole of NaOH is added to 1.00 L of the solution in Exercise 31, and calculate the pH after 0.20 mole of HCl is added to 1.00 L of the solution in Exercise 31.Data in
Calculate the pH after 0.10 mole of NaOH is added to 1.00 L of the solution in Exercise 32, and calculate the pH after 0.20 mole of HCl is added to 1.00 L of the solution in Exercise 32.Data in
Calculate the mass of sodium acetate that must be added to 500.0 mL of 0.200 M acetic acid to form a pH = 5.00 buffer solution.
Consider a solution that contains both C5H5N and C5H5NHNO3. Calculate the ratio [C5H5N]/[C5H5NH+] if the solution has the following pH values: a. pH = 4.50 b. pH = 5.00 c. pH = 5.23 d. pH = 5.50
Calculate the value of the equilibrium constant for each of the following reactions in aqueous solution. a. HC₂H₂O₂ + OHC₂H₂O₂ + H₂O b. C,H,O, +H*
Consider the following four titrations (i–iv):a. Rank the four titrations in order of increasing pH at the halfway point to equivalence (lowest to highest pH). b. Rank the four titrations in order
To what reaction does the solubility product constant, Ksp, refer? Table 15.1 lists Ksp values for several ionic solids. For any of these ionic compounds, you should be able to calculate the
Fig. 15.2 summarizes the classic method for separating a mixture of common cations by selective precipitation. Explain the chemistry involved with each of the four steps in the diagram.Fig. 15.2
Under what circumstances can you compare the relative solubilities of two salts directly by comparing the values of their solubility products? When can relative solubilities not be compared based on
Fig. 15.3 outlines the classic scheme for separating a mixture of insoluble chloride salts from one another. Explain the chemistry involved in the various steps of the figure.Fig. 15.3 Solution
Calculate the molar solubility of Cd(OH)2, Ksp = 5.9 × 10-11.
Calculate the molar solubility of Al(OH)3, Ksp = 2 × 10-32.
Calculate the molar solubility of Co(OH)3, Ksp = 2.5 × 10-43.
Calculate the solubility of Co(OH)2(s) (Ksp = 2.5 × 10-16) in a buffered solution with a pH of 11.00.
Order the following solids (a–d) from least soluble to most soluble. Ignore any potential reactions of the ions with water. a. AgCl Kp = 1.6 × 10-10 Ksp = 1.6 × 10- b. Ag₂S c. CaF₂ d. CuS Ksp
A 50.0-mL sample of 0.00200 M AgNO3 is added to 50.0 mL of 0.0100 M NaIO3. What is the equilibrium concentration of Ag+ in solution? (Ksp for AgIO3 is 3.0 × 10-8.)
Write equations for the stepwise formation of each of the following complex ions. a. Ni(CN)42-b. V(C2O4)33-
The Hg2+ ion forms complex ions with I- as follows:A solution is prepared by dissolving 0.088 mole of Hg(NO3)2 and 5.00 moles of NaI in enough water to make 1.0 L of solution. Hg²+ (aq) + I (aq)
Calculate the mass of manganese hydroxide present in 1300 mL of a saturated manganese hydroxide solution. For Mn(OH)2, Ksp = 2.0 × 10-13.
Calcium oxalate (CaC2O4) is relatively insoluble in water (Ksp = 2 × 10-9). However, calcium oxalate is more soluble in acidic solution. How much more soluble is calcium oxalate in 0.10 M H+ than in
You add an excess of solid MX in 250 g water. You measure the freezing point and find it to be -0.028°C. What is the Ksp of the solid? Assume the density of the solution is 1.0 g/cm3.
For the process A(1) → A(g), which direction is favored by changes in energy probability? Positional probability? Explain your answers. If you wanted to favor the process as written, would you
The free energy change, ΔG, for a process at constant temperature and pressure is related to ΔSuniv and reflects the spontaneity of the process. How is ΔG related to ΔSuniv? When is a process
Predict the sign of ΔS for each of the following and explain. a. The evaporation of alcohol b. The freezing of water c. Compressing an ideal gas at constant temperature d. Dissolving NaCl in
A mixture of hydrogen gas and chlorine gas remains unreacted until it is exposed to ultraviolet light from a burning magnesium strip. Then the following reaction occurs very rapidly: Explain.
Table 16.1 shows the possible arrangements of four molecules in a two-bulbed flask. What are the possible arrangements if there is one molecule in this two-bulbed flask or two molecules or three
What is the pH of a 0.125-M solution of the weak base B if ΔH° = -28.0 kJ and ΔS° = -175 J/K for the following equilibrium reaction at 25°C? B(aq) + H₂O(1) BH*(aq) + OH (aq)
Which of the following processes are spontaneous? a. A house is built. b. A satellite is launched into orbit. c. A satellite falls back to the earth. d. The kitchen gets cluttered.
One experimental procedure that can be used to determine the rate law of a reaction is the method of initial rates. What data are gathered in the method of initial rates, and how are these data
Consider the zero-, first-, and second-order integrated rate laws. If you have concentration versus time data for some species in a reaction, what plots would you make to “prove” a reaction is
Table 11.2 illustrates how the average rate of a reaction decreases with time. Why does the average rate decrease with time? How does the instantaneous rate of a reaction depend on time? Why are
At 40°C, H2O2(aq) will decompose according to the following reaction:The following data were collected for the concentration of H2O2 at various times.a. Calculate the average rate of decomposition

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