Indigo is the dye used in coloring blue jeans. The term navy blue is derived from the use of indigo to dye British naval uniforms in the eighteenth century. The structure of the indigo molecule is
b. What hybrid orbitals are used by the carbon atoms in the indigo molecule?
Draw the Lewis structures for TeCl 4, ICl5, PCl5, KrCl4, and XeCl2.
Which of the compounds exhibit at least one bond angle that is approximately 120 degrees?
Which of the compounds exhibit d 2sp3 hybridization?
Which of the compounds have a square planar molecular structure?
Which of the compounds are polar?
Write Lewis structures for CO32-, HCO3-, and H2CO3. When acid is added to an aqueous solution containing carbonate or bicarbonate ions, carbon dioxide gas is formed. We generally say that carbonic acid (H2CO3) is unstable. Use bond energies to estimate ΔE for the reaction (in the gas phase)
H2CO3 → CO2 + H2O
I - (aq) + OCl - (aq) → IO - (aq) + Cl - (aq)
was studied, and the following data were obtained:
c. Calculate the initial rate for an experiment where both I - and OCl - are initially present at 0.15 mol/L.
Sulfuryl chloride (SO2Cl2) decomposes to sulfur dioxide (SO2) and chlorine (Cl2) by reaction in the gas phase. The following pressure data were obtained when a sample containing 5.00 x 10-2 mol sulfuryl chloride was heated to 600. K in a 5.00 x 10 -1-L container.
Defining the rate as - Δ [SO2Cl2] / Δt,
a. determine the value of the rate constant for the decomposition of sulfuryl chloride at 600. K.
Write the rate laws for the following elementary reactions.
a. CH3NC (g) → CH3CN (g)
DDT (molar mass = 354.49 g/mol) was a widely used insecticide that was banned from use in the United States in 1973. This ban was brought about due to the persistence of DDT in many different ecosystems, leading to high accumulations of the substance in many birds of prey. The insecticide was shown to cause a thinning of egg shells, pushing many birds toward extinction. If a 20-L drum of DDT was spilled into a pond, resulting in a DDT concentration of 8.75 x 10-5 M, how long would it take for the levels of DDT to reach a concentration of 1.41 x 10-7 M (a level that is generally assumed safe in mammals)? Assume the decomposition of DDT is a first-order process with a half-life of 56.0 days.
At 40°C, H2O2(aq) will decompose according to the following reaction:
2H2O2 (aq) → 2H2O (l) + O2 (g)
The following data were collected for the concentration of H 2O2 at various times.
a. Calculate the average rate of decomposition of H 2O2 between 0 and 2.16 x 104 s. Use this rate to calculate the average rate of production of O2(g) over the same time period.
Pentane (C5H12) and hexane (C6H14) form an ideal solution. At 25°C the vapor pressures of pentane and hexane are 511 and 150. torr, respectively. A solution is prepared by mixing 25 mL pentane (density, 0.63 g/mL) with 45 mL hexane
(density, 0.66 g/mL).
b. What is the composition by mole fraction of pentane in the vapor that is in equilibrium with this solution?
The solubility of nitrogen in water is 8.21 x 10 -4 mol/L at 0°C when the N2 pressure above water is 0.790 atm. Calculate the Henry’s law constant for N2 in units of mol/L • atm for Henry’s law in the form C = kP, where C is the gas concentration in mol/L. Calculate the solubility of N2 in water when the partial pressure of nitrogen above water is 1.10 atm at 0°C.
The molar heat of fusion of benzene (C 6H6) is 9.92 kJ/mol. Its molar heat of vaporization is 30.7 kJ/mol. Calculate the heat required to melt 8.25 g benzene at its normal melting point. Calculate the heat required to vaporize 8.25 g benzene at its normal boiling point. Why is the heat of vaporization more than three times the heat of fusion?
Ethanol (C2H5OH) has been proposed as an alternative fuel. Calculate the standard enthalpy of combustion per gram of liquid ethanol.
Small quantities of hydrogen gas can be prepared in the laboratory by the addition of aqueous hydrochloric acid to metallic zinc.
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
Typically, the hydrogen gas is bubbled through water for collection and becomes saturated with water vapor. Suppose 240. mL of hydrogen gas is collected at 30.°C and has a total pressure of 1.032 atm by this process. What is the partial pressure of hydrogen gas in the sample? How many grams of zinc must have reacted to produce this quantity of hydrogen? (The vapor pressure of water is 32 torr at 30°C.)
Consider the following chemical equation.
2NO2(g) → N2O4(g)
If 25.0 mL NO2 gas is completely converted to N2O4 gas under the same conditions, what volume will the N2O4 occupy?
Freon-12 (CF2Cl2) is commonly used as the refrigerant in central home air conditioners. The system is initially charged to a pressure of 4.8 atm. Express this pressure in each of the following units (1 atm = 14.7 psi).
What mass of barium sulfate can be produced when 100.0 mL of a 0.100-M solution of barium chloride is mixed with 100.0 mL of a 0.100-M solution of iron(III) sulfate?
Mercury poisoning is a debilitating disease that is often fatal. In the human body, mercury reacts with essential enzymes leading to irreversible inactivity of these enzymes. If the amount of mercury in a polluted lake is 0.4 μg Hg/mL, what is the total mass in kilograms of mercury in the lake? (The lake has a surface area of 100 mi2 and an average depth of 20 ft.)
The stable isotopes of iron are 54Fe, 56Fe, 57Fe, and 58Fe. The mass spectrum of iron looks like the following:
Use the data on the mass spectrum to estimate the average atomic mass of iron, and compare it to the value given in the periodic table.
Identify the element whose ground-state electron configuration is [Ar] 4s2 3d10 4p2.
Determine the maximum number of electrons that can have each of the following designations: 2f, 2dxy, 3p, 5dyz, and 4p.
Write the expected ground-state electron configuration for the (as yet undiscovered) alkaline earth metal after radium.
How many orbitals in an atom can have the designation 5p, 3dz 2, 4d, n = 5, n = 4?