Atmospheric CO2 levels have risen by nearly 20% over the past 40 years from 315 ppm to 380 ppm. (a) Given that the average pH of clean, unpolluted rain today is 5.4, determine the pH of unpolluted rain 40 years ago. Assume that carbonic acid (H2CO3) formed by the reaction of CO2 ...
23 Aug 2021The densities of the elements K, Ca, Sc, and Ti are 0.86, 1.5, 3.2, and 4.5 g/cm3, respectively. One of these elements crystallizes in a body-centered cubic structure; the other three crystallize in a face-centered cubic structure. Which one crystallizes in the body-centered cubi...
23 Aug 2021The accompanying diagram shows how the free energy, G, changes during a hypothetical reaction A(g) B(g C(g). On the left are pure reactants A and B, each at 1 atm, and on the right is the pure product, C, also at 1 atm. Indicate whether each of the following statements is true o...
23 Aug 2021Ortho-dichlorobenzene, C6H4Cl2, is obtained when two of the adjacent hydrogen atoms in benzene are replaced with Cl atoms. A skeleton of the molecule is shown here. (a) Complete a Lewis structure for the molecule using bonds and electron pairs as needed. (b) Are there any resonan...
23 Aug 2021Lauryl alcohol is obtained from coconut oil and is used to make detergents. A solution of 5.00 g of lauryl alcohol in 0.100 kg of benzene freezes at 4.1 °C. What is the molar mass of lauryl alcohol from this data?
23 Aug 2021Indicate whether each statement is true or false. (a) The third law of thermodynamics says that the entropy of a perfect, pure crystal at absolute zero increases with the mass of the crystal. (b) “Translational motion” of molecules refers to their change in spatial location as a ...
23 Aug 2021NaF has the same structure as NaCl. (a) Use ionic radii from Chapter 7 to estimate the length of the unit cell edge for NaF. (b) Use the unit cell size calculated in part (a) to estimate the density of NaF.
23 Aug 2021Write the chemical equation and the Ka expression for the acid dissociation of each of the following acids in aqueous solution. First show the reaction with Haq) as a product and then with the hydronium ion: (a) C6H5COOH, (b) HCO3
23 Aug 2021The enthalpy of evaporation of water is 40.67 kJ/mol. Sunlight striking Earth’s surface supplies 168 W per square meter (1 W = 1 watt = 1 J/s). (a) Assuming that evaporation of water is due only to energy input from the Sun, calculate how many grams of water could be evaporated f...
23 Aug 2021Addition of the indicator methyl orange to an unknown solution leads to a yellow color. The addition of bromthymol blue to the same solution also leads to a yellow color. (a) Is the solution acidic, neutral, or basic? (b) What is the range (in whole numbers) of possible pH values...
23 Aug 2021Consider a mixture of two gases, A and B, confined in a closed vessel. A quantity of a third gas, C, is added to the same vessel at the same temperature. How does the addition of gas C affect the following: (a) the partial pressure of gas A, (b) the total pressure in the vessel, ...
23 Aug 2021Identify the Lewis acid and Lewis base among the reactants in each of the following reactions:(a) Fe(ClO43s) 6 H2O(l Fe(H2O)63aq) 3 ClO4aq (b) CNaq) H2O(l HCN(aq) OHaq (c) (CH33N(g) BF3g (CH33NBF3s (d) HIO(lq) NH2lq NH3lq) IOlq lq denotes liquid ammonia as solvent)
23 Aug 2021The precipitation reaction between AgNO3aq) and NaCl(aq) proceeds as follows: AgNO3aq) NaCl(aq NaNO3aq) AgCl(sa) By using data in Appendix C, calculate ∆H° for the net ionic equation of this reaction. (b) What would you expect for the value of ∆H° of the overall molecular equa...
23 Aug 2021For each of the following processes, indicate whether the signs of ∆S and ∆H are expected to be positive, negative, or about zero. (a) A solid sublimes. (b) The temperature of a sample of Co(s) is lowered from 60 °C to 25 °C. (c) Ethyl alcohol evaporates from a beaker. (d) A diat...
23 Aug 2021An important reaction for the conversion of natural gas to other useful hydrocarbons is the conversion of methane to ethane.2 CH4g C2H6g) H2gIn practice, this reaction is carried out in the presence of oxygen, which converts the hydrogen produced into water.2 CH4g O2g C2H6g) H2...
23 Aug 2021If a neutral solution of water, with pH = 7.00, is cooled to 10 °C, the pH rises to 7.27. Which of the following three statements is correct for the cooled water: (i) [H] ˃ [OH], (ii) [H] = [OH], or (iii) [H
23 Aug 2021For the elementary process N2O5g NO2g) NO3g) the activation energy (Ea) and overall ∆E are 154 kJ/mol and 136 kJ/mol, respectively. (a) Sketch the energy profile for this reaction, and label Ea and ∆Eb) What is the activation energy for the reverse reaction?
23 Aug 2021Consider the following standard reduction potentials: Al3 (aq) 3 e- → Al(s) E° = -1.66 V I2(s) 2 e- → 2 I-(aq) E° = 0.54 V Under standard conditions,a. Al3(aq) is a stronger oxidizing agent than I2(s), and I-(aq) is a stronger reducing agent than Al(s).b. Al(s) is a stronger ox...
23 Aug 2021Consider the reaction4 NH3g) 5 O2g 4 NO(g) 6 H2O(gH = –904.4 kJDoes each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (a) increase [NH3(b) increase [H2O]; (c) decrease [O2(d) decrease the volume of the container in which the reaction o...
23 Aug 2021a) Draw the dominant Lewis structure for the phosphorus trifluoride molecule, PF3b) Determine the oxidation numbers of the P and F atoms. (c) Determine the formal charges of the P and F atoms.
23 Aug 2021Write balanced equations that describe the formation of the following compounds from elements in their standard states, and then look up the standard enthalpy of formation for each substance in Appendix C: (a) H2O2g(b) CaCO3sc) POCl3ld) C2H5OH(l
23 Aug 2021Calculate the molar concentration of OH in a 0.724 M solution of hypobromite ion (BrOKb = 4.0 × 10-6). What is the pH of this solution?
23 Aug 2021In the lab, you will need to perform serial dilutions. What would be the concentration of the new solution made if you took 2.50 mL of a 0.10 M Cu(2) solution and diluted it to 10.00 mL?
23 Aug 2021A mixture of 0.10 mol of NO, 0.050 mol of H2, and 0.10 mol of H2O is placed in a 1.0-L vessel at 300 K. The following equilibrium is established:2 NO(g) 2 H2g N2g) 2 H2O(gAt equilibrium [NO] = 0.062 M(a) Calculate the equilibrium concentrations of H2, N2, and H2O. (b) Calculate...
23 Aug 2021Consider the molecule PF4Cl. (a) Draw a Lewis structure for the molecule, and predict its electron-domain geometry. (b) Which would you expect to take up more space, a P–F bond or a P–Cl bond? Explain. (c) Predict the molecular geometry of PF4Cl. How did your answer for part (b) ...
23 Aug 2021The volume of an adult’s stomach ranges from about 50 mL when empty to 1 L when full. If the stomach volume is 400 mL and its contents have a pH of 2, how many moles of H does the stomach contain? Assuming that all the H comes from HCl, how many grams of sodium hydrogen carbonate...
23 Aug 2021Determine whether each of the following statements concerning the titrations in Problem 17.35 is true or false. (a) The pH at the beginning of the two titrations will be the same. (b) The titration curves will both be essentially the same after passing the equivalence point. (...
23 Aug 2021The accompanying photo shows the reaction between a solution of Cd(NO32 and one of Na2S. (a) What is the identity of the precipitate? (b) What ions remain in solution? (c) Write the net ionic equation for the reaction. (d) Is this a redox reaction?
23 Aug 2021The accompanying photo shows the reaction between a solution of Cd(NO32 and one of Na2S. (a) What is the identity of the precipitate? (b) What ions remain in solution? (c) Write the net ionic equation for the reaction. (d) Is this a redox reaction?
23 Aug 2021What is the hydronium ion concentration and the pH for an aqueous solution of NH3 that has a hydroxide ion concentration of 2.25 × 10-5 mol L-1?
23 Aug 2021Identify two ions that have the following ground-state electron configurations: (a) [Ar], (b) [Ar]3d5c) [Kr]5s24d10
23 Aug 2021The U.S. quarter has a mass of 5.67 g and is approximately 1.55 mm thick. (a) How many quarters would have to be stacked to reach 575 ft, the height of the Washington Monument? (b) How much would this stack weigh? (c) How much money would this stack contain? (d) The U.S. National...
23 Aug 2021Some sulfuric acid is spilled on a lab bench. You can neutralize the acid by sprinkling sodium bicarbonate on it and then mopping up the resultant solution. The sodium bicarbonate reacts with sulfuric acid according to:2 NaHCO3s) H2SO4aq Na2SO4aq) 2 H2O(l) 2 CO2gSodium bicarbon...
23 Aug 2021In a hydrocarbon solution, the gold compound (CH33AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH33AuPH3a) What is the overall reaction? (b) What are the intermediates in the mec...
23 Aug 2021Consider the following unbalanced oxidation-reduction reactions in aqueous solution: Agaq) Li(s Ag(s) Liaq Fe(s) Naaq Fe2aq) Na(s K(s) H2O(l KOH(aq) H2ga) Balance each of the reactions. (b) By using data in Appendix C, calculate ∆H° for each of the reactions. (c) Based o...
23 Aug 2021The allowable concentration level of vinyl chloride, C2H3Cl, in the atmosphere in a chemical plant is 2.0 10-6 g/L. How many moles of vinyl chloride in each liter does this represent? How many molecules per liter?
23 Aug 2021In the following three instances which choice is greener in each situation? Explain. (a) Benzene as a solvent or water as a solvent. (b) The reaction temperature is 500 K, or 1000 K. (c) Sodium chloride as a by-product or chloroform (CHCl3) as a by-product.
23 Aug 2021Which of the following diagrams best represents an aqueous solution of NaF? (For clarity, the water molecules are not shown.) Will this solution be acidic, neutral, or basic?
23 Aug 2021The Sun radiates energy into space at the rate of 3.9 × 1026 J/s. (a) Calculate the rate of mass loss from the Sun in kg/s. (b) How does this mass loss arise? (c) It is estimated that the Sun contains 9 × 1056 free protons. How many protons per second are consumed in nuclear reac...
23 Aug 2021An “emulsifying agent” is a compound that helps stabilize a hydrophobic colloid in a hydrophilic solvent (or a hydrophilic colloid in a hydrophobic solvent). Which of the following choices is the best emulsifying agent? (a) CH3COOH, (b) CH3CH2CH2COOH, (c) CH3(CH211COOH, (d) CH3(C...
23 Aug 2021Explain the following observations: (a) The highest fluoride compound formed by nitrogen is NF3, whereas phosphorus readily forms PF5b) Although CO is a well-known compound, SiO does not exist under ordinary conditions. (c) AsH3 is a stronger reducing agent than NH3
23 Aug 2021Suppose that on another planet the atmosphere consists of 17% Kr, 38% CH4, and 45% O2. What is the average molar mass at the surface? What is the average molar mass at an altitude at which all the O2 is photodissociated?
23 Aug 2021Consider S, Cl, and K and their most common ions. (a) List the atoms in order of increasing size. (b) List the ions in order of increasing size. (c) Explain any differences in the orders of the atomic and ionic sizes.
23 Aug 2021Explain why any substance’s heat of fusion is generally lower than its heat of vaporization.
23 Aug 2021The value of Ksp for Cd(OH)2 is 2.5 × 10-14a) What is the molar solubility of Cd(OH)2b) The solubility of Cd(OH)2 can be increased through formation of the complex ion CdBr42 –Kf = 5 × 103). If solid Cd(OH)2 is added to a NaBr solution, what is the initial concentration of NaBr n...
23 Aug 2021Sulfur dioxide reacts with strontium oxide as follows:SO2g) SrO(g SrSO3s(a) Without using thermochemical data, predict whether ∆G° for this reaction is more negative or less negative than ∆H(b) If you had only standard enthalpy data for this reaction, estimate of the value of ∆G...
23 Aug 2021a) Do colloids made only of gases exist? Why or why not? (b) In the 1850’s, Michael Faraday prepared ruby-red colloids of gold nanoparticles in water that are still stable today. These brightly colored colloids look like solutions. What experiment(s) could you do to determine whe...
23 Aug 2021a) The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. Combustion of 2.78 mg of ethyl butyrate produces 6.32 mg of CO2 and 2.58 mg of H2O. What is the empirical formula of the compound? (b) Nicotine, a component of to...
23 Aug 2021An ester is a compound formed by a condensation reaction between a carboxylic acid and an alcohol that eliminates a water molecule. Read the discussion of esters in Section 24.4 and then give an example of a reaction forming an ester. How might this kind of reaction be extended t...
23 Aug 2021The compound chloral hydrate, known in detective stories as knockout drops, is composed of 14.52% C, 1.83% H, 64.30% Cl, and 13.35% O by mass (error, should be 19.35), and has a molar mass of 165.4 g/mol. (a) What is the empirical formula of this substance? (b) What is the molecu...
23 Aug 2021