Straighterline Chemistry Final Complete Questions And Answers | 100% Correct Answers | 2024 Updated Quiz

findings that are summarized based on a pattern or trend - Law tentative explanation for a set of observations - Hypothesis If a liquid contains 60% sugar and 40% water throughout its composition then what is it called? - Homogeneous mixture does not have a uniform composition throughout - Heterogeneous mixture represents a physical change? - Water, when heated, forms steam. How many micrograms are in 65.3 kg? - e. 6.53 × 1010 μg A smart phone has dimensions of 4.9 inches (height), 2.3 inches (width) and 8.0 millimeters (depth). What is the volume of the smart phone in cubic centimeters? (1 in = 2.54 cm) - 58 cm3 Given that 1 inch = 2.54 cm, 1.00 cm3 is equal to - 0.0610 in3 What terms defines a mass which is exactly equal to 1/12 the mass of one carbon-12 atom? - Atomic mass unit How many neutrons are there in an atom of lead whose mass number is 208? - 126 Which of these elements is chemically similar to magnesium? - Calcium C(graphite) and C(diamond) are examples of: - allotropes of carbon. The 80Br- ion has - 35 protons, 45 neutrons, 46 electrons. The formula for sodium sulfide is - Na2S Which one of the following formulas of ionic compounds is the least likely to be correct? - Ca2NO3 What is the name of ClO - ion? - hypochlorite Which of the following is a molecular formula for a compound with an empirical formula of CH? - C6H6 What is the energy in joules of a mole of photons associated with red light of wavelength 7.00 × 102 nm? (c = 3.00 × 108 m/s; h = 6.63 × 10-34 J • s; NA = 6.022 × 1023 /mole) - 1.71 × 105 J Which is the correct electron configuration for gold? - [Xe]4f145d106s1 Use the Rydberg equation to calculate the frequency of a photon absorbed when the hydrogen atom undergoes a transition from n1 = 2 to n2 = 4. (R = 1.096776 × 107 m-1; c = 3.00 × 108 m/s) - 6.17 × 1014 s-1 A 6.0-gram champagne cork is shot out of an opened champagne bottle and traveled at a speed of 65 km/hour. Calculate the de Broglie wavelength (in meters) of the cork. - 6.1 × 10-33 m A(n) _________ is a point at which a standing wave has zero amplitude. - node Calculate the wavelength associated with a 20Ne+ ion moving at a velocity of 2.0 × 105 m/s. The atomic mass of Ne-20 is 19.992 amu. (1 amu = 1.66 × 10-24 g and h = 6.63 × 10-34 J • s) - 1.0 × 10-13 m The Pauli exclusion principle states that no ____ electrons within an atom can have the same ____ quantum numbers. - 2; 4 Emission spectra - can be used to identify unknown atoms. Which one of the following equations correctly represents the process relating to the ionization energy of X? - X(g) → X+(g) + e- How does atomic radius change as you move across the periodic table? - Atomic radius decreases moving from left to right across a period and increases from top to bottom. Which of these choices is the electron configuration of the iron(III) ion? - a. [Ar]3d5 An element with the general electron configuration for its outermost electrons of ns2np1 would be in which element group? - b. 3A The effective nuclear charge for an atom is less than the actual nuclear charge due to - shielding. Which pair of ions exhibits the greatest attractive force between them? - Mg2+ and O2- Which of the following is a basic oxide? - MgO Which of these compounds is most likely to be covalent? - CS2 In the Lewis structure of the iodate ion, IO3-, that satisfies the octet rule, the formal charge on the central iodine atom is - 2. Which molecule has the largest dipole moment? - HF In which of the following species does the central atom violate the octet rule? - b. SF4 Which of these ionic solids would have the largest lattice energy? - CaCl2 The total number of bonding electrons in a molecule of formaldehyde (H2CO) is - 8. Which of the following molecules has a nonzero dipole moment? - SF2 According to the VSEPR model, a molecule with the general formula AB5 with one lone pair on the central atom will have a ______ molecular geometry - square pyramidal Which is the most reasonable prediction for the three F-Br-F bond angles in BrF3? - c. 86°, 86°, and 172° When PCl5 solidifies it forms PCl4+cations and PCl6- anions. According to valence bond theory, what hybrid orbitals are used by phosphorus in the PCl4+cation? - c. sp3 According to the VSEPR model, which one of the following molecules and ions will definitely have at least one 90° bond angle in it? (In each case, except water, the central atom is the first one in the formula.) - c. PCl5 What is the number of lone electron pairs on the central atom of a molecule having a trigonal pyramidal molecular geometry, such as NH3? - a. 1 For which one of the following molecules is the indicated type of hybridization not appropriate for the central atom? - a. BeCl2; sp2 According to the VSEPR model, the predicted molecular geometry of ammonia, NH3, is - e. trigonal pyramidal. What is the mass of one copper atom? (NA = 6.022 × 1023 mol-1) - a. 1.055 × 10-22 g What is the percent sulfur in iron(III) sulfate? - c. 24% Proteins found in humans are polymers that consist of different combinations of 20 amino acids. Proline, one of the 20 amino acids, has the molecular formula, C5H9NO2. If a human protein has 25 proline monomers, how many carbon atoms from proline are present in the protein? - e. 125 C atoms Aluminum oxide, Al2O3, is used as a filler for paints and varnishes as well as in the manufacture of electrical insulators. Calculate the number of moles in 47.51 g of Al2O3. - d. 0.4660 mol If 119.3 g of PCl5 are formed from the reaction of 61.3 g Cl2 with excess PCl3, what is the percent yield? PCl3(g) + Cl2(g) → PCl5(g) - b. 66.3% What mass of ammonia is formed when 5.36 g of nitrogen gas reacts with excess hydrogen gas? - e. 6.52 g Once the following equation is balanced with the smallest set of whole number coefficients, what is the sum of the coefficients? (Don't forget to include coefficients of one.) __ SF4 + __ H2O → __ H2SO3 + __ HF - d. 9 What is the theoretical yield of chromium that can be produced by the reaction of 40.0 g of Cr2O3 with 8.00 g of aluminum according to the chemical equation below? 2Al + Cr2O3 → Al2O3 + 2Cr - b. 15.4 g What is the pH of a 0.050 M triethylamine, (C2H5)3N, solution? Kb for triethylamine is 5.3 × 10-4. - a. 11.69 Which one of the following is a strong acid? - e. HClO3 Which is a Lewis acid? - b. BCl3 Which is an amphoteric oxide? - c. Al2O3 What is the value of the equilibrium constant for the autoionization of water at 25°C? - b. 1.0 × 10-14 What is the pH of a 0.056 M HNO3 solution? - b. 1.25 What is the pH of a 0.0100 M sodium benzoate solution? Kb (C7H5O2-) = 1.5 × 10-10 - d. 8.09 Which is the strongest acid? - C. H2SO4 Solid sodium peroxide (Na2O2) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released if 327.2 g of oxygen gas is produced from the reaction of sodium peroxide and water under standard-state conditions? Substance ΔH°f(kJ/mol) Na2O2(s) -510.9 NaOH(aq) -469.6 H2O(l) -285.8 - e. 2914 kJ Based on the following thermochemical equations, what is the heat of vaporization of titanium(IV) chloride? Ti(s) + 2 Cl2(g) → TiCl4(l) ΔH = -804.2 kJ/mol TiCl4(g) → 2 Cl2(g) + Ti(s) ΔH = 763.2 kJ/mol - a. +41.0 kJ/mol Calculate the standard enthalpy change for the reaction 2C8H18(l) + 21O2(g) → 8CO(g) + 8CO2(g) + 18H2O(l). Given: 2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l) ΔH° = -11,020. kJ/mol 2CO(g) + O2(g) → 2CO2(g) ΔH° = -566.0 kJ/mol - b. -8756 kJ/mol Styrene, C8H8, is one of the substances used in the production of synthetic rubber. When styrene burns in oxygen to form carbon dioxide and liquid water under standard-state conditions at 25°C, 42.15 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25°C. ΔH°f(CO2(g)) = -393.5 kJ/mol, ΔH°f(H2O(l)) = -285.8 kJ/mol - d. +99 kJ/mol How much heat is released if 35.0 g of ethanol (C2H5OH) burns in excess oxygen? C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l) ΔH°rxn = -1367 kJ/mol - e. 1040 kJ Suppose a 50-g block of silver (specific heat = 0.2350 J/g·°C) at 100°C is placed in contact with a 50-g block of iron (specific heat = 0.4494 J/g·°C) at 0°C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocks - b. will be lower than 50°C. How much heat is required to raise the temperature of 22.8 g of copper from 20.0°C to 875.0°C? The specific heat of copper is 0.385 J/g·°C. - c. 7.51 kJ A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/°C. What is the specific heat of copper? - a. 0.385 J/g·°C What is the temperature in Celsius at 4 K, which is the normal boiling point of liquid helium? - a. -269°C A 0.271-g sample of an unknown vapor occupies 294 mL at 140°C and 847 mmHg. The empirical formula of the compound is CH2. What is the molecular formula of the compound?(R = 0.08206 L • atm/K • mol) - b. C2H4 In the van der Waals equation, the constant b is a constant that is part of a correction factor for - a. the volume of the gas A sample of nitrogen gas at 298 K and 745 torr has a volume of 37.42 L. What volume will it occupy if the pressure is increased to 894 torr at constant temperature? - b. 31.2 L If the atmospheric pressure in Denver is 0.8800 atm, what is this pressure expressed in mmHg? (1 atm = 101,325 Pa = 760 torr, 1 torr = 1 mmHg)? - e. 668.8 mmHg What is the volume of NH3 produced in the following reaction when 3.0 L of N2 reacts with 4.0 L of H2 ? N2(g) + 3H2(g) → 2NH3(g) - b. 2.7 L What are the conditions of STP? - b. 273.15 K and 760 torr In the van der Waals equation, the constant a is a constant that is part of a correction factor for _ - c. the pressure of the gas Diethyl ether, (CH3CH2)2O, used as a solvent for extraction of organic compounds from aqueous solutions, has a high vapor pressure, which makes it a potential fire hazard in laboratories in which it is used. How much energy is released when 100.0 g is cooled from 53.0°C to 10.0°C? Normal boiling point 34.5°C Heat of vaporization 351 J/g Specific heat of (CH3CH2)2O(l) 3.74 J/g • °C Specific heat of (CH3CH2)2O(g) 2.35 J/g • °C - e. 48.6 kJ Which substance will exhibit hydrogen bonding between molecules? - c. CH3CH2-OH Which of the following statements is true? - c. The stronger the intermolecular forces, the higher the viscosity. If liquid bromine is cooled to form a solid, which type of solid does it form? - c. molecular In a sample of hydrogen iodide, __________________ are the most important intermolecular forces. - a. dipole-dipole forces Krypton has a higher melting point than argon because of its - b. stronger dispersion forces. Lead crystallizes in the face-centered cubic lattice. What is the coordination number for Pb? - e. 12 What states that the solubility of a gas in a liquid is proportional to the pressure of the gas over the solution? - b. Henry's law Which of the following pairs of liquids is least likely to be miscible? - c. Hexane-acetic acid What is the name given to a solution that contains less solute than it has the capacity to dissolve? - a. Unsaturated An emulsion is a dispersion consisting of a - b. liquid in a liquid. Calcium nitrite is used as a corrosion inhibitor in lubricants. What is the molality of a solution prepared by dissolving 18.5 g of calcium nitrite in 83.5 g of distilled water? - e. 1.68 m Which is true regarding the solvation of a solute in a solvent? - b. Separation of solute molecules from one another is an exothermic process, and separation of solvent molecules from one another is an endothermic process. What name is given to a minor component in a solution? - d. Solute What mass of ethanol (C2H5OH), a nonelectrolyte, must be added to 10.0 L of water to give a solution that freezes at -10.0°C? Assume the density of water is 1.0 g/mL. (Kf of water is 1.86°C/m.) - d. 2.48 kg The molar solubility of tin(II) iodide is 1.28 × 10-2 mol/L. What is Ksp for this compound? - a. 8.39 × 10-6 Which compound has the lowest solubility in pure water? - c. FePO4, Ksp = 1.3 × 10-22 Calculate the solubility of zinc hydroxide, Zn(OH)2, in 1.00 M NaOH. Ksp= 3.0 × 10-16 for Zn(OH)2, Kf = 3.0 × 1015 for Zn(OH)42- - e. 0.24 M Calculate the minimum concentration of Mg2+ that must be added to 0.10 M NaF in order to initiate a precipitate of magnesium fluoride. [Ksp(MgF2) = 6.9 × 10-9] - e. 6.9 × 10-7 M What happens to the solution if sodium acetate is added to a solution of acetic acid? CH3COOH(aq) Picture H+(aq) + CH3COO-(aq) - d. There is an increased concentration of acetate ions. Which is more soluble in an acidic solution than in pure water? - c. Ca3(PO4)2 What is the name of the principle of selective precipitation used to identify the types of ions present in a solution? - e. Qualitative analysis A 10.0-mL sample of 0.75 M CH3CH2COOH is titrated with 0.30 M NaOH. What is the pH of the solution after 22.0 mL of NaOH have been added to the acid? [Ka(CH3CH2COOH) = 1.3 × 10-5] - a. 5.75 Methyl red is a common acid-base indicator. It has a Ka equal to 6.3 × 10-6. Its un-ionized form is red and its anionic form is yellow. What color would a methyl red solution have at pH = 7.8? - d. yellow A 25.0-mL sample of 0.10 M C2H5NH2 (ethylamine) is titrated with 0.15 M HCl. What is the pH of the solution after 9.00 mL of acid have been added to the amine? [Kb(C2H5NH2) = 6.5 × 10-4] - b. 10.74 A 35.0-mL sample of 0.20 M LiOH is titrated with 0.25 M HCl. What is the pH of the solution after 23.0 mL of HCl have been added to the base? - c. 12.33 A 25.0-mL sample of 1.00 M NH3 is titrated with 0.15 M HCl. What is the pH of the solution after 15.00 mL of acid have been added to the ammonia solution? [Kb(NH3) = 1.8 × 10-5] - a. 10.26 When a strong acid is titrated with a weak base, the pH at the equivalence point - c. is less than 7.0. A buffer is prepared by adding 300.0 mL of 2.0 M NaOH to 500.0 mL of 2.0 M CH3COOH. What is the pH of this buffer? [Ka(CH3COOH) = 1.8 × 10-5] - d. 4.92 Which is necessary for a process to be spontaneous? - d. ΔSuniv 0 As the molar mass of a compound increases, the entropy ______. - c. increases What is ΔS° for the reaction SO2(s) + NO2(g) → SO3(g) + NO(g)? Substance S°(J/K • mol) SO2(g) 248.5 SO3(g) 256.2 NO(g) 210.6 NO2(g) 240.5 - c. -22.2 J/K • mol The most probable state is the one with the _______. - b. largest number of possible arrangements What is ΔS° for the reaction SO3(g) + H2O(l) → H2SO4(aq)? Substance S°(J/K • mol) SO3(g) 256.2 H2O(l) 69.9 H2SO4(aq) 156.9 - c. -169.2 J/K • mol A spontaneous endothermic reaction always - a. causes the surroundings to get colder. Consider the figure below which shows ΔG° for a chemical process plotted against absolute temperature. Which one of the following is an incorrect conclusion, based on the information in the diagram? - d. ΔS° increases with temperature while ΔH° remains constant. The element oxygen was prepared by Joseph Priestley in 1774 by heating mercury(II) oxide: HgO(s) → Hg(l) + ½O2(g), ΔH° = 90.84 kJ/mol. Estimate the temperature at which this reaction will become spontaneous under standard state conditions. S°(Hg) = 76.02 J/K • mol S°(O2) = 205.0 J/K • mol S°(HgO) = 70.29 J/K • mol - e. 840. K Which of the following is used to image the brain? - c. 123I Sodium-21 will emit positrons, each having an energy of 4.0 × 10-13 J. What is this energy in MeV? (1 MeV = 1.602 × 10-13 J) - b. 2.5 MeV Calcium-39 undergoes positron decay. Each positron carries 5.49 MeV of energy. How much energy will be emitted when 0.00250 mol of calcium-39 decays? (1 MeV = 1.602 × 10-13 J) - c. 1.32 × 106 kJ Which of the following is an advantage of nuclear power plants over coal-burning plants? Nuclear power plants - b. do not pollute the air with SO2, soot, and fly-ash. Which isotope, when bombarded with nitrogen-15, yields four neutrons and the artificial isotope dubnium-260? - d. Californium-249 Which isotope, when bombarded with bismuth-209, would yield two neutrons and an isotope with atomic number 121 and mass number 299? - c. Sr-92 Which name could correspond to the following coordination compound, where M represents a transition metal cation and L represents a ligand? - e. All of the above are possible Ethylenediaminetetraacetic acid (EDTA) is - b. an effective antidote for heavy metal poisoning (e.g., Pb2+ and Hg2+). In the coordination compound [Pt(NH3)2Cl2], the coordination number and oxidation number of the central atom are_____ and _____, respectively. - d. 4; +2 What is the systematic name for [CoCl3(H2O)]-? - c. aquatrichlorocobaltate(II) In K4[Fe(CN)6], how many 3d electrons does the iron atom have? - d. 6 Write the formula for diamminedichloroethylenediaminecobalt(III) bromide. - a. [CoCl2(en)(NH3)2]Br In the complex ion [Co(en)2Br2]+, what is the oxidation number of Co? - c. +3 In which type of isomerism is there restricted rotation around a bond? - b. Geometrical isomers What name is given to a compound containing a -CONH2 group? - c. Amide Bromination of benzene (C6H6), an aromatic compound, - a. occurs by substitution rather than addition. Which one of these materials is a copolymer? - a. Polystyrene-polybutadiene The density of a substance is an intensive property. - True The rusting of a piece of iron under environmental conditions is a physical change. - False 77 K is colder than 4 K. - False Zero kelvin 0 K 0°F 0°C - True The number 6.0448, rounded to 3 decimal places, becomes 6.045. - True A scoop of vanilla ice cream is a pure substance. - False The juice from an orange is a mixture. - True The ripening of fruit, once picked, is an example of physical change. - False A particular temperature in degrees Celsius is larger than the temperature in kelvins. - False Matter is anything that has mass and occupies space. - True Elements in which the outermost electron has the same principal quantum number, n, show similar chemical properties. - False Atomic size decreases across a period due to an increase in the effective nuclear charge, Zeff. - True The radii of ions are always smaller than the radii of the corresponding atoms of the same element. - False The electron configuration of atomic argon is the same as the chloride ion (Cl-). - True Moseley's measurements of nuclear charges of the elements provided the basis for arranging the elements of the periodic table in order of increasing atomic number. - True Only valence electrons are shown in the Lewis structure held together by covalent bonds. - True Unshared electrons are always shown in pairs around an atom. - False Lewis theorized the octet rule to describe chemical bonding where atoms lose, gain, or share electrons in order to achieve a noble gas configuration. - True Ionic compounds tend to form between metals and nonmetals when electrons are transferred from an element with high ionization energy (metal) to an element with a low electron affinity (nonmetal). - False When an alkali metal combines with a nonmetal, a covalent bond is normally formed. - False The empirical formula is the simplest whole number ratio of atoms representing a chemical formula of a molecule. - True Many compounds can be represented with the same empirical formula. - False The molecular formula is a whole number multiple of the empirical formula. - True There is only one distinct empirical formula for each compound that exists. - True Amphoteric oxides are compounds that exhibit both acidic and basic behavior. - True If a strong acid such as HCl is diluted sufficiently with water, the pH will be higher than 7. - False Kw = 1.0 × 10-14 under all conditions. - False A hydrohalic acid is a binary acid containing a halogen. - True Weak acids have weak conjugate bases. - False The rate of diffusion of a gas is inversely proportional to its molar mass. - False Gases are compressible and have a density that is much higher than liquids and solids. - False For a gas obeying Boyle's law, a plot of V versus 1/P will give a straight line passing through the origin. - False For real gases, PV nRT. - False When a closed-ended manometer is used for pressure measurements, and the closed end is under vacuum, the level of manometer liquid in the closed arm can never be lower than that in the other arm. - True Ethanol (C2H5-OH) will have a greater viscosity than ethylene glycol (HO-CH2CH2-OH) at the same temperature. - False Ice is less dense than water due to the formation of hydrogen bonds. - True A face-centered crystal lattice has one atom in the center of the unit cell. - False The energy of a hydrogen bond is greater than that of a typical covalent bond. - False The maximum number of phases of a single substance which can coexist in equilibrium is two. - False The endpoint is used to estimate the equivalence point. - True If the pH of a buffer solution is greater than the pKa value of the buffer acid, the buffer will have more capacity to neutralize added base than added acid. - False For a conjugate acid-base pair, Kw = Ka/Kb - False The amount of strong acid added to a buffer solution cannot exceed the original amount of conjugate base present in order for the buffer to still work. - True The endpoint in a titration is defined as the point when the appropriate indicator changes color. - True Increasing the concentrations of the components of a buffer solution will increase the buffer capacity. - True A CH3COOH/CH3COO- buffer can be produced by adding a strong acid to a solution of CH3COO- ions. - True Indicators are weak acids that are one color in acidic solution and another color in basic solution. - True The pH of a solution that is 0.20 M CH3COOH and 0.20 M CH3COONa should be higher than the pH of a 0.20 M CH3COOH solution. - True Increasing the concentrations of the components of a buffer solution will increase the buffer range. - False For stable atoms of elements having low atomic numbers (≤ 20), the neutron-to-proton ratio is close to zero. - False Nuclear fission is the process in which a heavy nucleus (mass number 200) divides to form smaller nuclei of intermediate mass and one or more protons. - False Gamma rays are high energy electrons. - False In a nuclear reaction elements are converted to other elements. - True A nuclear reaction's reaction rate is affected by temperature, pressure, and catalysts. - False The correct formula for the dibromobis(oxalato)cobaltate(III) ion is [Co(C2O4)Br2]3+. - False The maximum oxidation state of an element in the first transition series never exceeds its group number. - True In complexes of transition metals, the maximum coordination number of the metal is equal to its number of d electrons. - False The systematic name of the coordination compound K2[Co(H2O)2I4] is potassium diaquotetraiodocobaltate(II). - True A complex ion that undergoes a very slow exchange reaction is called an inert complex. - True What is the vapor pressure above a beaker containing a solution of NaCl that is made up of 250ml of water and 12g of NaCl? - b. 23.4 mmHg Plants use up copious amounts of which alkali metal, preventing most of it from being washed out to sea? - c. potassium Which of the following isotopes is likely to be the most stable? - d. Sn-50 Ernest Rutherford disproved J.J. Thomson's plum-pudding model of the atom by showing that - c. positive matter is concentrated in the central core. What is the reducing agent in the following equation? Mg(s) + 2 HCl(aq) -- MgCl2(aq) + H2(g) - A. Mg How is the mass number of an element different from its atomic number? - c. The mass number represents the total number of neutrons and protons in one atom of the element as opposed to the total number of protons What is Avogadro's number? - a. the number of atoms in 12g of Carbon-12 What is the ratio of reactants and products in the chemical equation? NaOH + H2SO4 == Na2SO4 + H2O - d. 2:1:1:2 The initial volume of a system containing 1 mole of an ideal gas at 292° Kelvin and 3 atm is 8 L. If the gas is cooled at constant volume until the pressure falls to 1.2 atm, then the gas is heated and expanded at constant pressure (1.2 atm) until the volume is 20 L and the temperature is 292° Kelvin, what is the overall work that has been done by the system? - b. -1.46 kJ Most nonmetallic elements are found in which block of the periodic table of elements? - b. p Which arrangement accurately describes the standard entropy values for Na at different phases? - c. Na (s) Na (l) Na (g) What element has been oxidized and what element has been reduced in the redox reaction shown? 3CuS + 8HNO3 == 3CuSO4 + 8NO + 4H20 - c. Sulfur has been oxidized; nitrogen has been reduced. When iron ions react with water, some of the iron ions will combine with water molecules, like this: Fe3+(aq) + 3H2O(l) à Fe(OH)3(s) + 3H+(aq) In this case, is the iron ion acting like an acid or a base? Explain. - B. The iron ion is acting like an acid. It has accepted a pair of electrons from the oxygen, which agrees with the Lewis definition of an acid. Ammonia is a vitally important industrial chemical. Fertilizers and nitric acid (an important industrial chemical itself) are produced from ammonia. The Haber-Bosch process is used to create ammonia, and has two major steps: a) CH4(g) + H2O(g) à 2 H2(g) + CO(g) b) 3 H2(g) + N2(g) à 2 NH3(g) Is either of these steps an oxidation-reduction reaction? If so, identify which elements are oxidized, which are reduced and which are neither oxidized nor reduced. - A. Both of these steps are oxidation-reduction reactions. Calculate Ecell for the galvanic cell based on these half-reactions at 25oC, in which [H2SO4] = 0.5 M HSO4- (aq) + Pb (s) H+ (aq) + PbSO4 (s) + 2 e- Eo = +0.35 V PbO2 (s) + 3H+ (aq) + HSO4- (aq) + 2 e- PbSO4 (s) + 2H2O (l) Eo = +1.46 V If the concentration of sufuric acid is increased, will Ecell increase or decrease? Explain. - D. Ecell = 1.79 V. Changing the concentration of sulfuric acid will increase Ecell because log Q will become smaller. Acetic acid is a very important industrial chemical and is produced by this reaction: CH3OH(l) + CO(g) à CH3COOH(l) Calculate the value of the standard Gibbs Free Energy change for this reaction. Is acetic acid thermodynamically stable compared with liquid water at standard conditions? Explain.CompoundStandard Gibbs Free Energy (kJ/mol)H2O (l)-237.1 CH3COOH -389.9 CH3OH (I) -166.6 CO (g) -137.3 - A. ΔG°rxn = -86.0 kJ; At standard conditions, acetic acid is less thermodynamically stable than water because it has a more negative value of ΔG°. Acetylene (properly known as ethyne) and calcium hydroxide are the products of the reaction between calcium carbide (CaC2) and water. Ethyne can be easily set on fire. This can be done on the surface of an ice cube, giving it the appearance of "burning ice". Identify the balanced reaction for the combustion of ethyne and explain why it burns with intense heat. - D. 2C2H2 + 5O2 à 4CO2 + 2H2O; There is a lot of energy released in this reaction because the energy released when forming the chemical bonds in four moles of CO2 and two moles of water H2O is much more than the energy required to break the chemical bonds in two moles of ethyne and five moles of oxygen. In some enzymatic reactions, the product of the reaction that is catalyzed by the enzyme is able to bind to the active site on the enzyme itself. What effect would this have on the activity of the enzyme? Could this be a biologically useful feature in some situations? Explain. - C. This would inhibit the enzyme's activity, slowing it down. Yes, this could be biologically useful because it could prevent over-production of the product. Silicon can be "doped" with other elements by adding small amounts of those elements to the silicon. This can make "n-type" or "p-type" semiconductors, depending on what is added to the silicon. What type of semiconductor would be produced by adding indium to silicon? Why? Which element could you add to make the opposite type of semiconductor? - D. Doping silicon with indium produces a "p-type" semiconductor. This is because the indium has fewer valence electrons than silicon, and this will produce positively charged "holes" in the electron structure. Adding arsenic to silicon would produce an "n-type" semiconductor. Atoms that have the same number of protons but different numbers of neutrons are called - Isotopes proposed an atomic theory in 1808. - John Dalton The magnitude of the electron charge was discovered by - R. Millikan E. Rutherford is credited with discovering the - Nucleus Metals and non-metals are separated in the periodic table by a(n) - Staircase Horizontal rows in the periodic table are called - Periods In a chemical reaction, the reactant that is used up first is the ___________. - Limiting reagent The concentration of a solution is termed its ________. - Molarity The chemical formula of a compound determined from its molecular mass is called the ____________. - Molecular Formula A phase diagram is a diagram depicting the phases of a substance at different temperatures and pressures. - True Phase change is a physical change involving a substance changing from one state of matter to another, such as liquid to gas. - True Surface tension is the tendency of liquids to maximize their surface area. - False Sublimation is a phase change involving a substance changing from solid directly to gas. - True The solubility of ionic compounds in water is mainly determined by _________ forces. - Viscosity Solids can be divided into two categories, crystalline and ______. - Amorphous The two types of close-packing are called cubic close-packing and ______ close-packing. - Hexagonal Three types of atomic solids are nonbonded, metallic, and _____________. - Network covalent Effusion is the transfer of gas through a small orifice into an evacuated chamber. - True Kinetic molecular theory is a basic atomic model that describes the behavior of liquids. - False Boyle's law is a gas law that associates the product of the pressure and volume with the number of moles, temperature, and a universal proportionality constant. - True Standard temperature and pressure are conditions defined as 0ºC and 1 atm. - True The solubility of ionic compounds in water is mainly determined by ________ forces. - Ion-dipole An alloy is an example of a _______ solution. - solid-solid A concentration term commonly used for solutions that uses the volume of a solution is ______. - Molarity The Tyndall effect is the effect whereby a colloidal solution interacts with electricity. True False - False Raoult's law applies to a solution comprised of a non-volatile solute and is the relationship between the vapor pressure of the solution and the vapor pressure of the pure solvent. - True Boiling point elevation is a colligative property that involves the increase in the boiling point of a solvent by the addition of a solute - True Colligative properties are concerned with the type of particles and not their number. - False When a solid is dissolved in water and forms a solution that conducts electricity, the solid is called a(n) ___________. - Electrolyte Two dissolved ions in hard water are Mg2+ and _________. - Ca2+ When a solid comes out of a solution, the solid is called a(n) ________. - Precipitate Acid-base reactions are also called ________ reactions. - Neutralization Who defined an acid as a proton donor and a base as a hydroxide donor? - Arrhenius A reaction where electrons are transferred from one reactant to another is called a(n) __________ reaction. - Redox or oxidation-reduction The fact that two electrons in the same orbital must have opposite spins is called the ________. - Pauli exclusion principle The p-orbitals can hold a maximum of _____ electrons. - Six The d orbitals can hold a maximum of ____ electrons. - Ten The actual nuclear charge minus the charge from the core electrons is the ____________. - Effective nuclear charge Unreactive gases that have a full valence shell of electrons are known as the _________. - Noble gases A reaction in which the same element gains and loses electrons is known as a(n) ________ reaction. - Disproportionation The Haber process is used to manufacture ________. - Ammonia The ________ is a point charge model that involves metal d orbitals and ligands. - Crystal field model _____ is a trend that describes ligands from strong field to weak field. - The spectrochemical series A coordination environment where a metal is surrounded by six ligands is called _______. - Octahedral A reduction in atomic radii caused by the 4f electrons being close to the nucleus is called ______. - Lanthanide contraction A ligand that forms one bond to the metal is called a(n) _________. - Unidentate