Chemistry Concepts and Calculations, Exams of Advanced Education

Download Chemistry Concepts and Calculations and more Exams Advanced Education in PDF only on Docsity! Straighterline Chemistry Final Exam With 100% Correct Answers 2023 What is the term used for findings that are summarized based on a pattern or trend? a. Law b. Hypothesis c. Theory d. Phenomena e. Prediction - Correct Answer-a. Law Which of the following is a tentative explanation for a set of observations? Select one: a. Law b. Hypothesis c. Theory d. Phenomena e. Prediction - Correct Answer-b. Hypothesis If a liquid contains 60% sugar and 40% water throughout its composition then what is it called? Select one: a. Solute b. Compound c. Homogeneous mixture d. Heterogeneous mixture e. Solvent - Correct Answer-c. Homogeneous mixture Which of the following does not have a uniform composition throughout? Select one: a. Element b. Compound c. Homogeneous mixture d. Heterogeneous mixture e. Solvent - Correct Answer-d. Heterogeneous mixture Which one of these represents a physical change? Select one: a. Water, when heated, forms steam. b. Bleach turns hair yellow. c. Sugar, when heated, becomes brown. d. Milk turns sour. e. Apples, when exposed to air, turn brown. - Correct Answer-a. Water, when heated, forms steam. How many micrograms are in 65.3 kg? Select one: a. 0.653 μg b. 6.53 × 107 μg c. 6.53 × 104 μg d. 6.53 × 10-8 μg e. 6.53 × 1010 μg - Correct Answer-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) Select one: a. 58 cm3 b. 1.7 x 105 cm3 c. 90 cm3 d. 3.4 cm3 e. 34 cm3 - Correct Answer-a. 58 cm3 Given that 1 inch = 2.54 cm, 1.00 cm3 is equal to Select one: a. 16.4 in3 b. 6.45 in3 c. 0.394 in3 d. 0.155 in3 e. 0.0610 in3 - Correct Answer-e. 0.0610 in3 What terms defines a mass which is exactly equal to 1/12 the mass of one carbon-12 atom? Select one: a. Isotope number b. Mass number c. Mass-to-charge ratio d. Atomic number e. Atomic mass unit - Correct Answer-e. Atomic mass unit How many neutrons are there in an atom of lead whose mass number is 208? Select one: a. 82 b. 126 c. 208 d. 290 e. none of them - Correct Answer-b. 126 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. Select one: a. 6.1 × 10-33 m b. 1.7 × 10-36 m c. 6.1 × 10-36 m d. 1.7 × 10-33 m e. 5.5 × 10-20 m - Correct Answer-a. 6.1 × 10-33 m A(n) _________ is a point at which a standing wave has zero amplitude. Select one: a. crevice b. node c. pit d. burrow e. orbital - Correct Answer-b. 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) Select one: a. 1.0 × 10-13 m b. 1.0 × 10-16 m c. 1.0 × 10-18 m d. 9.7 × 1012 m e. 2.0 × 10-13 cm - Correct Answer-a. 1.0 × 10-13 m The Pauli exclusion principle states that no ____ electrons within an atom can have the same ____ quantum numbers. Select one: a. 4; 6 b. 2; 4 c. 3; 6 d. 6; 10 e. 3; 8 - Correct Answer-b. 2; 4 Emission spectra Select one: a. cannot be used to identify an unknown atom. b. can be used to identify unknown atoms. c. can be explained by the movement of protons colliding with electrons. d. none of the. - Correct Answer-b. can be used to identify unknown atoms. Which one of the following equations correctly represents the process relating to the ionization energy of X? Select one: a. X(s) → X+(g) + e- b. X2(g) → X+(g) + X-(g) c. X(g) + e- → X-(g) d. X-(g) → X(g) + e- e. X(g) → X+(g) + e- - Correct Answer-e. X(g) → X+(g) + e- Consider the element with the electron configuration [Kr]5s24d105p5. This element is Select one: a. a halogen. b. a transition metal. c. an alkali metal. d. an actinide element. e. a noble gas. - Correct Answer-a. a halogen. Consider the element with the electron configuration [Kr]5s24d7. This element is Select one: a. a halogen. b. a transition metal. c. a nonmetal. d. an actinide element. e. a noble gas. - Correct Answer-b. a transition metal. How does atomic radius change as you move across the periodic table? Select one: a. Atomic radius decreases moving from left to right across a period and increases from top to bottom. b. Atomic radius increases moving left to right across a period and decreases from top to bottom. c. Smaller nuclear charge lowers energy; more electrons in an orbital lowers energy. d. Atomic radius increases diagonally across the periodic table. e. None of the answers is correct. - Correct Answer-a. 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? Select one: a. [Ar]3d5 b. [Ar]4s13d5 c. [Ar]4s23d3 d. [Ar]3d6 e. [Ar]4s23d9 - Correct Answer-a. [Ar]3d5 An element with the general electron configuration for its outermost electrons of ns2np1 would be in which element group? Select one: a. 2A b. 3A c. 4A d. 5A e. 8A - Correct Answer-b. 3A The effective nuclear charge for an atom is less than the actual nuclear charge due to Select one: a. shielding. b. penetration. c. paramagnetism. d. electron-pair repulsion. e. relativity. - Correct Answer-a. shielding. Which pair of ions exhibits the greatest attractive force between them? Select one: a. Na+ and Cl- b. Ca2+ and Cl- c. Na+ and S2- d. Al3+ and Mg2+ e. Mg2+ and O2- - Correct Answer-e. Mg2+ and O2- Which of the following is a basic oxide? Select one: a. P4O10 b. MgO c. Al2O3 d. SO2 e. Cl2O7 - Correct Answer-b. MgO Which of these compounds is most likely to be covalent? Select one: a. Rb2S b. SrCl2 c. CS2 d. CaO e. MgI2 - Correct Answer-c. CS2 In the Lewis structure of the iodate ion, IO3-, that satisfies the octet rule, the formal charge on the central iodine atom is Select one: a. 2. b. 1. For which one of the following molecules is the indicated type of hybridization not appropriate for the central atom? Select one: a. BeCl2; sp2 b. SiH4; sp3 c. BF3; sp2 d. C2H2; sp e. H2O; sp3 - Correct Answer-a. BeCl2; sp2 According to the VSEPR model, the predicted molecular geometry of ammonia, NH3, is Select one: a. linear. b. trigonal planar. c. bent. d. tetrahedral. e. trigonal pyramidal. - Correct Answer-e. trigonal pyramidal. What is the mass of one copper atom? (NA = 6.022 × 1023 mol-1) Select one: a. 1.055 × 10-22 g b. 63.55 g c. 1 amu d. 1.66 × 10-24 g e. 9.476 × 1021 g - Correct Answer-a. 1.055 × 10-22 g What is the percent sulfur in iron(III) sulfate? Select one: a. 28% b. 32% c. 24% d. 48% e. 42% - Correct Answer-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? Select one: a. 4 C atoms b. 25 C atoms c. 40 C atoms d. 100 C atoms e. 125 C atoms - Correct Answer-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. Select one: a. 2.377 mol b. 2.146 mol c. 1.105 mol d. 0.4660 mol e. 0.4207 mol - Correct Answer-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) Select one: a. 94.6% b. 66.3% c. 57.3% d. 51.3% e. 48.6% - Correct Answer-b. 66.3% What mass of ammonia is formed when 5.36 g of nitrogen gas reacts with excess hydrogen gas? Select one: a. 3.26 g b. 0.629 g c. 13.04 g d. 17.63 g e. 6.52 g - Correct Answer-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 Select one: a. 4 b. 6 c. 7 d. 9 e. None of these answers is correct. - Correct Answer-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 Select one: a. 7.7 g b. 15.4 g c. 27.4 g d. 30.8 g e. 49.9 g - Correct Answer-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. Select one: a. 11.69 b. 8.68 c. 5.32 d. 2.31 e. 1.30 - Correct Answer-a. 11.69 Which one of the following is a strong acid? Select one: a. CH3COOH b. H2SO3 c. NH3 d. H3PO4 e. HClO3 - Correct Answer-e. HClO3 Which is a Lewis acid? Select one: a. CH3NH2 b. BCl3 c. F- d. BF4- e. CH4 - Correct Answer-b. BCl3 Which is an amphoteric oxide? Select one: a. Na2O b. MgO c. Al2O3 d. SO2 e. Cl2O7 - Correct Answer-c. Al2O3 What is the value of the equilibrium constant for the autoionization of water at 25°C? Select one: a. 1.0 × 10-7 b. 1.0 × 10-14 c. 1.0 × 1014 d. 1.0 × 107 e. 14 - Correct Answer-b. 1.0 × 10-14 e. cannot be predicted. - Correct Answer-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. Select one: a. 14.4 J b. 176 J c. 7.51 kJ d. 7.68 kJ e. 9.90 kJ - Correct Answer-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? Select one: a. 0.385 J/g·°C b. 1.83 × 104 J/g·°C c. 2.60 J/g·°C d. 1.32 J/g·°C e. 24.5 J/g·°C - Correct Answer-a. 0.385 J/g·°C What is the temperature in Celsius at 4 K, which is the normal boiling point of liquid helium? Select one: a. -269°C b. 269°C c. 277°C d. 68.3°C e. -277°C - Correct Answer-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) Select one: a. CH2 b. C2H4 c. C3H6 d. C4H8 e. C6H12 - Correct Answer-b. C2H4 In the van der Waals equation, the constant b is a constant that is part of a correction factor for _________. Select one: a. the volume of the gas b. the temperature of the gas c. the pressure of the gas d. the ideal gas constant - Correct Answer-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? Select one: a. 22.3 L b. 31.2 L c. 44.9 L d. 112 L e. 380 L - Correct Answer-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)? Select one: a. 151.5 mmHg b. 1.16 × 10-3 mmHg c. 863.6 mmHg d. 8.92 × 104 mmHg e. 668.8 mmHg - Correct Answer-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) Select one: a. 1.5 L b. 2.7 L c. 6.0 L d. 7.5 L e. 12 L - Correct Answer-b. 2.7 L What are the conditions of STP? Select one: a. 0 K and 1 atm b. 273.15 K and 760 torr c. 0°C and 760 atm d. 273.15°C and 760 torr e. 0°C and 1 torr - Correct Answer-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 _________. Select one: a. the volume of the gas b. the temperature of the gas c. the pressure of the gas d. the ideal gas constant - Correct Answer-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 Select one: a. 10.1 kJ b. 16.1 kJ c. 21.6 kJ d. 35.1 kJ e. 48.6 kJ - Correct Answer-e. 48.6 kJ Which substance will exhibit hydrogen bonding between molecules? Select one: a. (CH3)3N b. CH3-O-CH3 c. CH3CH2-OH d. CH3CH2-F e. HI - Correct Answer-c. CH3CH2-OH Which of the following statements is true? Select one: a. The higher the viscosity, the faster a liquid flows. b. The viscosity increases with increasing temperature. c. The stronger the intermolecular forces, the higher the viscosity. d. Hydrogen bonding in water gives rise to its unusually low viscosity. e. The viscosity of gases is larger than the viscosity of liquids. - Correct Answer-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? Select one: a. atomic b. metallic c. molecular d. ionic e. covalent - Correct Answer-c. molecular In a sample of hydrogen iodide, __________________ are the most important intermolecular forces. Select one: a. dipole-dipole forces 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.) Select one: a. 85.7 kg b. 24.8 kg c. 5.38 kg d. 2.48 kg e. 1.17 kg - Correct Answer-d. 2.48 kg The molar solubility of tin(II) iodide is 1.28 × 10-2 mol/L. What is Ksp for this compound? Select one: a. 8.39 × 10-6 b. 1.28 × 10-2 c. 4.20 × 10-6 d. 1.64 × 10-4 e. 2.10 × 10-6 - Correct Answer-a. 8.39 × 10-6 Which compound has the lowest solubility in pure water? Select one: a. Ag2C2O4, Ksp = 1.0 × 10-11 b. PbCl2, Ksp = 1.7 × 10-5 c. FePO4, Ksp = 1.3 × 10-22 d. Ca3(PO4)2, Ksp = 1.2 × 10-26 e. MgF2, Ksp = 6.9 × 10-9 - Correct Answer-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- Select one: a. 0.60 M b. 0.52 M c. 0.37 M d. 0.32 M e. 0.24 M - Correct Answer-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] Select one: a. 1.4 × 107 M b. 6.9 × 10-9 M c. 6.9 × 10-8 M d. 1.7 × 10-7 M e. 6.9 × 10-7 M - Correct Answer-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) Select one: a. The equilibrium shifts to the right. b. There is an increase in percent ionization of acetic acid. c. Less of hydrogen ion is consumed. d. There is an increased concentration of acetate ions. e. Less of the acetate ion is consumed. - Correct Answer-d. There is an increased concentration of acetate ions. Which is more soluble in an acidic solution than in pure water? Select one: a. CuI b. PbCl2 c. Ca3(PO4)2 d. NaNO3 e. NaBr - Correct Answer-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? Select one: a. Ionization b. Selective ion precipitation c. Selective ion typing d. Limited precipitation e. Qualitative analysis - Correct Answer-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] Select one: a. 5.75 b. 4.94 c. 4.83 d. 4.02 e. 3.95 - Correct Answer-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? Select one: a. green b. red c. blue d. yellow e. violet - Correct Answer-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] Select one: a. 11.08 b. 10.74 c. 10.81 d. 10.55 e. 10.49 - Correct Answer-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? Select one: a. 1.26 b. 1.67 c. 12.33 d. 12.74 e. 13.03 - Correct Answer-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] Select one: a. 10.26 b. 9.30 c. 9.21 d. 8.30 e. 8.21 - Correct Answer-a. 10.26 When a strong acid is titrated with a weak base, the pH at the equivalence point Select one: a. is greater than 7.0. b. is equal to 7.0. c. is less than 7.0. d. is equal to the pKa of the conjugate acid. e. is equal to the pKb of the base. - Correct Answer-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] Select one: a. 4.57 b. 4.52 c. 4.87 d. 4.92 e. 4.97 - Correct Answer-d. 4.92 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 Select one: a. 108 K b. 430. K c. 620. K d. 775 K e. 840. K - Correct Answer-e. 840. K Which of the following is used to image the brain? Select one: a. 18O b. 131I c. 123I d. 24Na e. 99Tc - Correct Answer-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) Select one: a. 4.0 × 10-7 MeV b. 2.5 MeV c. 40 MeV d. 2.5 × 106 MeV e. 2.5 × 10-6 MeV - Correct Answer-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) Select one: a. 13.2 kJ b. 1.32 × 104 kJ c. 1.32 × 106 kJ d. 1.32 × 109 kJ e. None of these choices is correct. - Correct Answer-c. 1.32 × 106 kJ Which of the following is an advantage of nuclear power plants over coal-burning plants? Nuclear power plants Select one: a. form numerous radioactive fission products. b. do not pollute the air with SO2, soot, and fly-ash. Correct c. produce more thermal pollution than coal plants. d. use more fuel. - Correct Answer-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? Select one: a. Californium-245 b. Thorium-257 c. Nobelium-245 d. Californium-249 e. Dubnium-249 - Correct Answer-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? Select one: a. Pb-211 b. Po-209 c. Sr-92 d. Rn-38 e. Sr-38 - Correct Answer-c. Sr-92 Which name could correspond to the following coordination compound, where M represents a transition metal cation and L represents a ligand? Picture Select one: a. Hexachloroferrate(III) b. Hexaammineiron(III) c. Hexaaquochromium(II) d. Hexacyanomanganate(II) e. All of the above are possible. - Correct Answer-e. All of the above are possible Ethylenediaminetetraacetic acid (EDTA) is Select one: a. not useful as a chelating agent. b. an effective antidote for heavy metal poisoning (e.g., Pb2+ and Hg2+). c. a monodentate ligand. d. known to form unstable complex ions with Fe3+, Hg2+, and Zn2+. e. known to form complexes with platinum that inhibit the growth of cancerous cells. - Correct Answer-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. Select one: a. 2; 0 b. 4; +4 c. 5; 0 d. 4; +2 e. 6; +2 - Correct Answer-d. 4; +2 What is the systematic name for [CoCl3(H2O)]-? Select one: a. cobalt(III) chloride monohydrate b. aquatrichlorocobalt(II) c. aquatrichlorocobaltate(II) d. aquatrichlorocobaltite(I) e. monoaquotris(chloro)cobalt(IV) - Correct Answer-c. aquatrichlorocobaltate(II) In K4[Fe(CN)6], how many 3d electrons does the iron atom have? Select one: a. 3 b. 4 c. 5 d. 6 e. 7 - Correct Answer-d. 6 Write the formula for diamminedichloroethylenediaminecobalt(III) bromide. Select one: a. [CoCl2(en)(NH3)2]Br b. [CoCl2(en)(NH3) 2]Br2 c. [CoCl2(en)2(NH3)2]Br d. [CoCl2(en)2(NH3)2]Br2 e. (NH3)2Cl2(en)Co3Br - Correct Answer-a. [CoCl2(en)(NH3)2]Br In the complex ion [Co(en)2Br2]+, what is the oxidation number of Co? Select one: a. +1 b. +2 c. +3 d. -2 e. -1 - Correct Answer-c. +3 Elements in which the outermost electron has the same principal quantum number, n, show similar chemical properties. Select one: True False - Correct Answer-False Atomic size decreases across a period due to an increase in the effective nuclear charge, Zeff. Select one: True False - Correct Answer-True The radii of ions are always smaller than the radii of the corresponding atoms of the same element. Select one: True False - Correct Answer-False The electron configuration of atomic argon is the same as the chloride ion (Cl-). Select one: True False - Correct Answer-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. Select one: True False - Correct Answer-True Only valence electrons are shown in the Lewis structure held together by covalent bonds. Select one: True False - Correct Answer-True Unshared electrons are always shown in pairs around an atom. Select one: True False - Correct Answer-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. Select one: True False - Correct Answer-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). Select one: True False - Correct Answer-False When an alkali metal combines with a nonmetal, a covalent bond is normally formed. Select one: True False - Correct Answer-False The empirical formula is the simplest whole number ratio of atoms representing a chemical formula of a molecule. Select one: True False - Correct Answer-True Many compounds can be represented with the same empirical formula. Select one: True False - Correct Answer-False The molecular formula is a whole number multiple of the empirical formula. Select one: True False - Correct Answer-True There is only one distinct empirical formula for each compound that exists. Select one: True False - Correct Answer-True Amphoteric oxides are compounds that exhibit both acidic and basic behavior. Select one: True False - Correct Answer-True If a strong acid such as HCl is diluted sufficiently with water, the pH will be higher than 7. Select one: True False - Correct Answer-False Kw = 1.0 × 10-14 under all conditions. Select one: True False - Correct Answer-False A hydrohalic acid is a binary acid containing a halogen. Select one: True False - Correct Answer-True Weak acids have weak conjugate bases. Select one: True False - Correct Answer-False The rate of diffusion of a gas is inversely proportional to its molar mass. Select one: True False - Correct Answer-False Gases are compressible and have a density that is much higher than liquids and solids. Select one: True False - Correct Answer-False A CH3COOH/CH3COO- buffer can be produced by adding a strong acid to a solution of CH3COO- ions. Select one: True False - Correct Answer-True Indicators are weak acids that are one color in acidic solution and another color in basic solution. Select one: True False - Correct Answer-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. Select one: True False - Correct Answer-True Increasing the concentrations of the components of a buffer solution will increase the buffer range. Select one: True False - Correct Answer-False For stable atoms of elements having low atomic numbers (≤ 20), the neutron-to-proton ratio is close to zero. Select one: True False - Correct Answer-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. Select one: True False - Correct Answer-False Gamma rays are high energy electrons. Select one: True False - Correct Answer-False In a nuclear reaction elements are converted to other elements. Select one: True False - Correct Answer-True A nuclear reaction's reaction rate is affected by temperature, pressure, and catalysts. Select one: True False - Correct Answer-False The correct formula for the dibromobis(oxalato)cobaltate(III) ion is [Co(C2O4)Br2]3+. Select one: True False - Correct Answer-False The maximum oxidation state of an element in the first transition series never exceeds its group number. Select one: True False - Correct Answer-True In complexes of transition metals, the maximum coordination number of the metal is equal to its number of d electrons. Select one: True False - Correct Answer-False The systematic name of the coordination compound K2[Co(H2O)2I4] is potassium diaquotetraiodocobaltate(II). Select one: True False - Correct Answer-True A complex ion that undergoes a very slow exchange reaction is called an inert complex. Select one: True False - Correct Answer-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? a. 10.3 mmHg b. 23.4 mmHg c. 35.8 mmHg d. 63.2 mmHg - Correct Answer-b. 23.4 mmHg Plants use up copious amounts of which alkali metal, preventing most of it from being washed out to sea? a. lithium b. sodium c. potassium d. rubidium - Correct Answer-c. potassium Which of the following isotopes is likely to be the most stable? Select one: a. F-21 b. Kr-77 c. Po-210 d. Sn-50 - Correct Answer-d. Sn-50 Ernest Rutherford disproved J.J. Thomson's plum-pudding model of the atom by showing that a. atoms are, in fact, not electrically neutral. b. the atom contains neutrons. c. positive matter is concentrated in the central core. d. electrons are actually greater in mass than protons. - Correct Answer-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 b. HCl c. H2 d. MgCl2 - Correct Answer-A. Mg How is the mass number of an element different from its atomic number? Select one: a. The mass number represents the total number of protons in one atom of the element as opposed to the total number of neutrons. 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. B. Only reaction b) is an oxidation-reduction reaction. C. Only reaction a) is an oxidation-reduction reaction. D. No, neither of these reactions is an oxidation-reduction reaction. - Correct Answer-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. A. This question cannot be answered with the information given. Concentrations of the other reactants and products are necessary. B. Ecell = 1.80 V. Changing the concentration of sulfuric acid will increase Ecell because log Q will become smaller. C. Ecell = 1.81 V. Changing the concentration of sulfuric acid will not change Ecell. D. Ecell = 1.79 V. Changing the concentration of sulfuric acid will increase Ecell because log Q will become smaller. - Correct Answer-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. Compound Standard 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°. B. ΔG°rxn = -86.0 kJ; At standard conditions, acetic acid is more thermodynamically stable than water because it has a more negative value of ΔG°. C. 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°. D. . ΔG°rxn = -0.017 kJ; At standard conditions, acetic acid is less thermodynamically stable than water because it has a more negative value of ΔG°. - Correct Answer-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. A. 2C2H2 + 5O2 à 4CO2 + 2H2O; There is a lot of energy released in this reaction because there is a triple bond between the carbons in ethyne, which contains a lot of energy, and this energy is released when the bonds are broken. B. C2H4 + 3O2 à 2CO2 + 2H2O; There is a lot of energy released in this reaction because there is a double bond between the carbons in ethyne, which contains a lot of energy, and this energy is released when the bonds are broken. C. C2H4 + 3O2 à 2CO2 + 2H2O; There is a lot of energy released in this reaction because the energy released when forming the chemical bonds in two moles of CO2 and two moles of water H2O is much more than the energy required to break the chemical bonds in one mole of ethyne and three moles of oxygen. 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. - Correct Answer-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. A. This would inhibit the enzyme's activity, slowing it down. No, this could not be biologically useful and is the sign of a damaged enzyme. Enzymes should catalyze as many reactions as possible for biological efficiency. B. This would enhance the enzyme's activity, speeding it up. Yes, this could be biologically useful because it would maximize production of the product. 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. D. This would enhance the enzyme's activity, slowing it down. No, this would not be biologically useful because it would cause the enzyme to be less efficient. - Correct Answer-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? A. Doping silicon with indium produces a "p-type" semiconductor. This is because the indium has more protons than silicon, so it is a "p-type" semiconductor. Adding arsenic to silicon would produce an "n-type" semiconductor. True False - Correct Answer-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. - Correct Answer-True Standard temperature and pressure are conditions defined as 0ºC and 1 atm. - Correct Answer-True The solubility of ionic compounds in water is mainly determined by ________ forces. Ion-dipole Dipole-dipole Hydrogen-bonded - Correct Answer-Ion-dipole An alloy is an example of a _______ solution. - Correct Answer-solid-solid A concentration term commonly used for solutions that uses the volume of a solution is ______. - Correct Answer-Molarity The Tyndall effect is the effect whereby a colloidal solution interacts with electricity. True False - Correct Answer-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. - Correct Answer-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 - Correct Answer-True Colligative properties are concerned with the type of particles and not their number. - Correct Answer-False When a solid is dissolved in water and forms a solution that conducts electricity, the solid is called a(n) ___________. Metal Electrolyte Ion - Correct Answer-Electrolyte Two dissolved ions in hard water are Mg2+ and _________. Na+ Ca2+ Cu2+ - Correct Answer-Ca2+ When a solid comes out of a solution, the solid is called a(n) ________. Precipitate Salt Electrolyte - Correct Answer-Precipitate Acid-base reactions are also called ________ reactions. Neutralization Ionic Dipole - Correct Answer-Neutralization Who defined an acid as a proton donor and a base as a hydroxide donor? Avogrado Arrhenius Bohr - Correct Answer-Arrhenius A reaction where electrons are transferred from one reactant to another is called a(n) __________ reaction. Redox or oxidation-reduction Acid-base Ionic - Correct Answer-Redox or oxidation-reduction The fact that two electrons in the same orbital must have opposite spins is called the ________. Heisenberg uncertainty principle Pauli exclusion principle Electron configuration - Correct Answer-Pauli exclusion principle The p-orbitals can hold a maximum of _____ electrons. Six Two Ten - Correct Answer-Six The d orbitals can hold a maximum of ____ electrons. Four Six Ten - Correct Answer-Ten The actual nuclear charge minus the charge from the core electrons is the ____________. Effective nuclear charge Oxidation state Valence electron - Correct Answer-Effective nuclear charge Unreactive gases that have a full valence shell of electrons are known as the _________. Halides Noble gases Hydrogens - Correct Answer-Noble gases A reaction in which the same element gains and loses electrons is known as a(n) ________ reaction. Acid-base Dissolution Disproportionation - Correct Answer-Disproportionation The Haber process is used to manufacture ________. - Correct Answer-Ammonia The ________ is a point charge model that involves metal d orbitals and ligands. Crystal field model Acid-base model Ionic model - Correct Answer-Crystal field model _____ is a trend that describes ligands from strong field to weak field. Electronegativity The spectrochemical series The crystal field model - Correct Answer-The spectrochemical series A coordination environment where a metal is surrounded by six ligands is called _______. Linear Tetrahedral Octahedral - Correct Answer-Octahedral A reduction in atomic radii caused by the 4f electrons being close to the nucleus is called ______. Lanthanide contraction