CHEM 1009 FINAL EXAM QUESTIONS WITH CORRECT DETAILED ANSWERS

Density equation - correct answers Density = mass/volume Density units - correct answers g/mL or g/cm^3 double-displacement reaction - correct answers occurs readily among ionic compounds in solution when two ions that form an "insoluble" salt are mixed Average - correct answers mean average deviation - correct answers average of absolute deviations intensive properties - correct answers do not depend on the amount of matter present extensive properties - correct answers depend on the amount of matter present conversion factor - correct answers desired unit = given unit x (desired unit/ given unit) C to K conversion - correct answers K = C+273.15 F to C conversion - correct answers % error formula - correct answers (theoretical-actual)/theorecticalX100=? hottest part of flame - correct answers outermost zone know sig fig rules - correct answers state of CaCO₃ - correct answers solid Is oxygen soluble in water? - correct answers no. it is insoluble/ sparingly soluble in water Properties of O₂ gas - correct answers colorless odorless tasteless denser than air insoluble in water not highly reactive or active at room temp. basic oxides - correct answers metal oxide + water → metal hydroxide (base) examples of basic oxides - correct answers •BaO + H2O → Ba(OH)2 •K2O + H2O → 2KOH bases turn red litmus paper... - correct answers blue acidic oxides - correct answers nonmetal oxide + water →acid acidic oxide examples - correct answers •SO2(g) + H2O(l) → H2SO3 •SO3(g) + H2O(l) → H2SO4 •CO2(g) + H2O(l) → H2CO3 acids turn blue litmus paper... - correct answers red factors that affect the rate of a reaction - correct answers temperature concentration presence of catalyst surface area catalyst - correct answers substance that speeds up the rate of a reaction without being consumed How is oxygen prepared in the lab? - correct answers Oxygen is prepared by the thermal decomposition of oxygen containing compounds. Oxygen was collected by the displacement of water because oxygen is insoluble in water. Which catalyst did we use to prepare O₂ in the lab? - correct answers MnO₂ decomposition reaction of KClO₃ - correct answers 2KClO₃ → 2KCl + 3O₂ strong acids - correct answers Hydrochloric Acid (HCl), Hydrobromic Acid (HBr), Hydroiodic Acid (HI), Chloric Acid (HClO₃), Perchloric Acid (HClO₄), Nitric Acid (HNO₃), Sulfuric Acid (H₂SO₄) strong bases - correct answers Group 1A metal hydroxides [LiOH, NaOH, KOH, RhOH, CsOH], heavy group 2A metal hydroxides [Ca(OH)2, Sr(OH)2, Ba(OH)2] combustion reaction - correct answers hydrocarbon + oxygen → H₂O + CO₂ limiting reactant - correct answers present in the smallest stoichiometric amount; completely consumed in reaction theoretical yield - correct answers The maximum amount of a product that could be formed form a given amount of reactant actual yield - correct answers the amount produced and measured in the lab percent yield - correct answers Reason for a higher % yield of NaCl - correct answers you did NOT completely dry the NaCl (water was included in the mass) Reason for a lower % yield of NaCl - correct answers you over dried NaCl and some particles were lost law of definite proportions - correct answers the composition of a compound is always the same percent composition - correct answers hydrates - correct answers substances formed when water combines chemically in definite proportions with a salt anhydrous - correct answers form of the salt that is produced when all the water of hydration is lost examples of hydrates - correct answers (CaSO4)2 • H2O CaSO4 • 2H2O CuSO4 • 5H2O MgSO4 • 7H2O Na2CO3 • 10H2O What does • in a formula indicate? - correct answers • indicates a kind of chemical bond that usually can be easily broken Loss of hydration water to the atmosphere is called... - correct answers efflorescence The property of some salts to collect moisture from the air and dissolve in it is called... - correct answers deliquescence A compound is that absorbs moisture from the atmosphere without dissolution is said to be... - correct answers hygroscopic Is a reaction that results in a hydrate endothermic or exothermic? example: CuSO4(s) + 5H2O(l) → CuSO4•5H2O(s) - correct answers exothermic Is a reaction that results in an anhydrous substance endothermic or exothermic? example: CuSO4•5H2O(s) → CuSO4(s) + 5H2O(l) - correct answers endothermic In the thermal decomposition of KClOx, what does x represent? - correct answers X represents the ratio of moles of O to moles of KCl. X = (# mol O/ # mol KCl) oxidation - correct answers loss of electrons reduction - correct answers gain of electrons oxidation-reduction reaction - correct answers a reaction that involves the transfer of electrons between reactants How are the metals arranged in the activity series? - correct answers From the top to the bottom in the activity series, the elements are arranged in order of decreasing ease of oxidation. active metals - correct answers metals at the top of the activity series that can be easily oxidized noble metals - correct answers metals at the bottom of the activity series A metal in the activity series can only be oxidized by... - correct answers a metal ion below it Properties of H₂ Gas - correct answers colorless odorless tasteless slightly soluble in water diatomic much lighter than air highly flammable least dense gas factors that affect activity - correct answers concentration temperature surface area Molarity (M) - correct answers moles of solute/liters of solution Molarity equation - correct answers mass ÷ (MW × Volume in L) titration - correct answers a common way to determine the concentration of a given solution acid-base indicators - correct answers change color at the end point equivalence point - correct answers equal number of moles of each substance (neutralized) Which acid-base indicator did we use? - correct answers Phenolphthalein. It appears clear in acids and pink in bases. What is the difference between the end point and the equivalence point? - correct answers a titration error In the titration process, which substance is the titrant? - correct answers the titrant is the solution whose concentration has to be determined arrhenius acid - correct answers causes an increase in the concentration of H+ ions arrhenius base - correct answers causes an increase in the concentration of OH- ions know how to solve for unknown concentration - correct answers antacid - correct answers a substance such as a weak base or basic salt that is used to neutralize excess acid in thee stomach Is an antacid basic or acidic? - correct answers basic common active ingredients in antacids - correct answers CaCO₃ NaHCO₃ Al(OH)₃ Mg(OH)₂ Why might an antacid tablet not completely dissolve in the acid solution? - correct answers Some of these inactive ingredients are insoluble in water or even in HCl solution direct titration - correct answers titrant is added to analyte until the reaction is complete back titration - correct answers a known excess of reagent is added to analyte, and the excess is titrated with a second standard reagent Neutralization of calcium carbonate by aqueous hydrochloric acid (chemical equation) - correct answers CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g) + (excess HCl) Which household substance is frequently used as an antacid? - correct answers baking soda (NaHCO₃) 4 variables of gas - correct answers P, V, T, n Ideal Gas Law - correct answers PV = nRT What value do we use for R? - correct answers R = 0.08206 L × atm × mol-1 × K-1 1 atm = ?mm Hg = ?torr - correct answers 1 atm = 760 mm Hg = 760 torr Charle's law - correct answers at constant pressure, the volume and temperature of a gas are directly proportional V ÷ T = constant V = constant × T properties of gases - correct answers highly compressible expand to fill container non-reacting gas mixtures are homogeneous distance between gas molecules is large Boyle's Law - correct answers at constant temperature, the volume and pressure of a gas are inversely proportional PV = constant Molecular Weight of an ideal gas - correct answers M.W. = (mass x RT)/PV Why is it necessary to allow the test tube to cool before it is removed for weighing? - correct answers It necessary to allow the test tube to cool before weighing to avoid getting an unstable measurement due to convection currents. It is also necessary to allow the test tube to cool in order to weigh at the same conditions as the beginning of the experiment. Why must the water delivery tube extend nearly to the bottom of the bottle? - correct answers The water delivery tube must extend nearly to the bottom of the bottle to avoid losing some of the oxygen gas. When water flow ceases, what can be assumed as the relationship between barometric pressure (Patm) and the pressure inside the flask (Poxygen +Pwater)? - correct answers Patm = Poxygen + Pwater Is it necessary to decompose all the chlorate? - correct answers No, it is not necessary to decompose all the chlorate because we are going to weigh it at the end. What is the volume of 1 mol