163 Created by Master Student Chemistry Practice Test #10 1 / 30 How much water, in liters, must be added to 0.50 liter of 6.0 M HCl to make the solution 2.0 M? 0.33 0.5 1 1.5 2 (C) In dilution problems, the expressions M1e V1 = M2e V2 can be used. Substituting (6.0 M) (0.50 L) = (2.0 M) (x L) gives x = 1.5 L total volume. Since there was 0.50 L to begin with, an additional 1 L must be added. 2 / 30 In 12.4 hours, a 100 gram sample of an element decays so that its mass is 25 grams. What is the approximate half-life of this radioactive substance? 1.6 hours 3.1 hours 6.2 hours 24.8 hours 49.6 hours After 1 half-life, a 100 g sample will have a mass of 50 g. After 2 half-lives, it will have a mass of 25 g, so we're talking about the expiration of 2 half-lives. If 2 half-lives = 12.4 hours, then 1 half-life = 6.2 hours. 3 / 30 The oxidation number for hydrogen in NaH is 1+ 2+ 0 1- 2- 0 4 / 30 The most active metallic elements are found in the upper right corner of the periodic chart the lower right corner of the periodic chart the upper left corner of the periodic chart the lower left corner of the periodic chart the middle of the periodic chart, just beyond the transition elements (D) The most active metallic elements are found in the lower left corner of the Periodic Table. 5 / 30 If two atoms that differ in electronegativity combine by chemical reaction and share electrons, the bond that joins them will be metallic ionic a hydrogen bond nonpolar covalent polar covalent As soon as you hear the term electron sharing, you know you're dealing with a covalent bond, so eliminate (A), (B), and (C). The fact that the two atoms differ in electronegativity tells you that one has more attraction for the shared electrons than the other. The result? A polar covalent bond-the molecule has a negative and a positive pole. 6 / 30 Releases a gas with the addition of dilute acid KI CCl4 AgNO3 CaCO3 N2 Carbonates, CO32-, and bicarbonates, HCO3?, form CO2 gas when mixed with acid. That's why baking soda (NaHCO3) fizzes when added to vinegar (acetic acid). 7 / 30 Proposes basic postulates concerning elements and atoms Avogadro's number P1V1 = P2V2 V1T2 = V2T1 Dalton's Theory Gay-Lussac's Law (D) John Dalton is credited with the basic postulates of atomic theory. 8 / 30 Which salt listed in Appendix 4 of this book has the greatest solubility in water under equal conditions? Lead iodide Lead sulfate Magnesium hydroxide Silver chloride The salts are all equally soluble. 0 9 / 30 2Na(s) + Cl2(g) <=> 2NaCl(s) + 822 kJ How much heat is released by the above reaction if 0.5 mole of sodium reacts completely with chlorine? 205 kJ 411 kJ 822 kJ 1,640 kJ 3,290 kJ (A) In the equation, 2 mol of Na release 822 kJ of heat. If only 0.5 mol of Na is consumed, only one-fourth as much heat will be released:e 822 = 205 kJ. 10 / 30 Where are the highest ionization energies found in the Periodic Table? Upper left corner Lower left corner Upper right corner Lower right corner Middle of transition elements (C) The complete outer energy levels of electrons of the smallest noble gases have the highest ionization potential. 11 / 30 The key element delivered in soil fertilizer Carbon Nitrogen Oxygen Neon Argon Two elements that are essential to plant growth but are depleted in most soils are nitrogen and phosphorous. Phosphorous is not given as a choice, but nitrogen is. Plants cannot utilize atmospheric nitrogen gas because the strong triple bond in N2 makes it virtually inert to biological processing. 12 / 30 Has mass and occupies space Density A solid Volume Weight Matter (E) That a substance occupies space and mass is the basic definition of all matter. 13 / 30 The organic acid that can be made from ethanol is acetic acid formic acid C3H7OH found in bees and ants butanoic acid (A) Ethanol can be oxidized into the organic acid enthanoic acid, which has the common name of acetic acid. 14 / 30 The concentration of a solution of Ca(OH)2 when 74 grams are completely dissolved in a container holding 2 liters of water? 1 molar 1 molal .5 molar .5 molal 25 molar (C) The molar mass of Ca(OH)2 is Ca = 40, 2 O = 32, and 2 H = 2, which, added together equals 74 g/mol. If this is dissolved to make a 2 L solution, there is only .5 mol in 1 L. So the molarity (M), the moles of solute in 1 L = .5 M 15 / 30 What is the approximate pH of a 0.005 M solution of H2SO4? 1 2 5 9 13 (B) The pH is -log[H+]. A 0.005 molar solution of H2SO4 ionizes in a dilute solution to release two H+ ions per molecule of H2SO4. Therefore the molar concentration of H+ ion is 2e 0.005 mol/L or 0.010 mol/L. Substituting this in the formula, you have: 16 / 30 A transition element that occurs when the inner 3d orbital is partially filled Fe Au Na Ar U (A) Iron has 5 electrons in the d orbitals, which are partially filled. 17 / 30 Which of the following reactions produces a yellow precipitate? NaOH(aq) + HCl(aq) <=> NaCl(s) + H2O NaOH(aq) + BaCl(aq) <=> BaOH(s) + NaCl(aq) Pb(NO3)2(aq) + 2KI(aq) <=> 2KNO3(aq) + PbI2(s) CuO(s) + Mg(s) <=> Cu(s) + MgO(s) 4Fe + 3O2 <=> 2Fe2O3 Recall the solubility rules. (A) and (B) are incorrect because neither NaCl nor BaOH are insoluble and therefore would not precipitate out of the aqueous solution. Because lead salts are insoluble except for their nitrates and perchlorates, lead iodide would precipitate out of solution as (C) depicts. Answer choices (D) and (E) are examples of oxidation-reduction reactions. 18 / 30 When Fe2+ is oxidized to Fe3+, the Fe2+ ion loses 1 electron loses 1 proton gains 1 electron gains 1 proton gains 1 neutron 0 19 / 30 Which substance can be decomposed chemically? Ammonia Iron Neon Hydrogen Fluorine Next 20 / 30 Which of the following solids has a brilliant blue color? Ca(OH)2 KCl NaBr Fe2O3 CuSO4 Many colored compounds contain a transition metal (an element from the d region of the periodic table). Choices (A), (B), and (C) are ionic solids that possess an active metal (an element from the s region). These compounds appear white (for instance, NaCl or table salt). Choice (D) is rust, which is not blue. CuSO4 contains the transition metal copper (Cu), and its crystals are bright blue. 21 / 30 Which of the following is true regarding an Ne atom with a mass number of 20 and an O2- ion with a mass number of 16? They contain the same number of protons. They contain the same number of neutrons. They contain the same number of protons plus neutrons. They are isoelectronic. They are isomers. An O2- ion has gained 2 electrons to fill its outer shell. This gives an O2- ion the same electron configuration as Ne. That is, the 2 are isoelectronic. 22 / 30 What is the correct term for the phase change from gas directly to solid? Deposition Sublimation Liquefaction Fusion Vaporization The phase changes associated with the terms are 23 / 30 An element that has a high first ionization energy and is chemically inactive would most likely be a noble gas a transition element an alkali metal a halogen an alkaline earth metal 0 24 / 30 The type of bond between atoms of potassium and chloride when they form a crystal of potassium chloride Hydrogen bond Ionic bond Polar covalent bond Nonpolar covalent bond Metallic bond (B) Potassium and chlorine have a large enough difference in their electronegativities to form ionic bonds. The respective positions of these two elements in the periodic chart also are indicative of the large difference in their electronegativity values. 25 / 30 Has 7 valence electrons Na+ Al F Ti Br- Fluorine (F) has 7 electrons in its second shell, 1 short of a complete stable octet. 26 / 30 The reaction: HI(aq) + LiOH(aq) <=>H2O(l) + LiI(aq) is classified as a single replacement a neutralization reaction the process of hydrolysis a synthesis reaction an oxidation-reduction reaction 0 27 / 30 What is the molar concentration of a 500-milliliter solution that contains 20 grams of CaBr2 (formula weight = 200)? 0.1 molar 0.2 molar 0.5 molar 1 molar 5 molar Knowing that moles = , we can calculate the number of moles of CaBr2 in the solution. 28 / 30 A property that must decrease when a gas condenses into a liquid Standard voltaic potential Entropy Enthalpy Reaction rate Gibbs free energy Entropy, S, is the measure of the amount of disorder in a molecular system. When a gas condenses into a liquid, the molecules become more organized, so the entropy of the system decreases. 29 / 30 What is the percentage composition of calcium in calcium hydroxide, Ca(OH)2? (1 mol = 74 g) 40% 43% 54% 69% 74% (C) The percentage composition can be found by dividing each total atomic mass in the formula by the molar mass of the compound. 30 / 30 In the reaction 2KClO3 + MnO2 + 2KCl + 3O2 (g) + MnO2, which substance is the catalyst? O2 KClO3 MnO2 KCl O2 in the MnO2 (C) The catalyst, by definition, is not consumed in the reaction and ends up in its original form as one of the products. In this reaction, the catalyst is the MnO2. Your score is The average score is 57% LinkedIn Facebook Twitter VKontakte 0% Restart quiz Previous Quiz Next Quiz
