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UNIT 4 PROGRESS CHECK - MCQNa2CO3(aq) + 2 HCl(aq)→2 NaCl(aq) + H2O(l) + CO2(g)A student combined two colorless aqueous solutions. One of the solutions contained Na2CO3 as the solute and the other contained HCl. The chemical reaction that took place is represented by the equation above. What experimental result would be evidence that a chemical reaction took place when the solutions were combined?Bubbles formed when the two solutions were combined.The total volume of the mixture is close to the sum of the initial volumes.The resulting solution is colorless.The resulting solution conducts electricity.A chemistry teacher carried out several demonstrations, and students recorded their observations. For one of the demonstrations, a student concluded that a physical change took place, but not a chemical change. Which of the following observations could the student have made of the results of the demonstration?Two colorless solutions were combined, and the resulting solution was pink.When a solid was added to a liquid, sparks were produced.One piece of solid substance was changed into small pieces.When two solutions were combined, a precipitate formed.A student was given two clear liquids; a colorless liquid and a dark-blue liquid. The student was asked to combine the liquids in a beaker and record observations. Which of the following results, if true, would provide the best evidence that a chemical change took place when the liquids were combined?The resulting mixture was cloudy.The total volume of the mixture was equal to the sum of the initial volumes.The resulting liquid was light blue.The liquids formed two separate layers in the beaker.Which of the following is the correct net ionic equation of the neutralization reaction between hydrofluoric acid and sodium hydroxide in aqueous solution?HF(aq) + NaOH(aq) ? H2O(l) + NaF(aq)HF(aq) + NaOH(aq) ? NaH(aq) + FOH(aq)H+(aq) + OH?(aq) ? H2O(l)HF(aq) + OH?(aq) ? H2O(l) + F?(aq)Which of the following is the correct net ionic equation of the reaction that occurs when aqueous solutions of ammonia and hydrochloric acid are combined?NH3(aq) + HCl(aq)→NH4Cl(aq)NH3(aq) + H+(aq)→NH4+(aq)NH3(aq) + HCl(aq)→NH4+(aq) + Cl?(aq)NH3(aq) + H+(aq) + Cl?(aq)→NH4+(aq) + Cl?(aq)A beaker was half filled with freshly distilled H2O and placed on a hot plate. As the temperature of the water reached 100°C, vigorous bubbling was observed in the beaker. The gaseous contents of the bubbles were analyzed. The presence of which of the following substances would support the claim that the observed phenomenon was a physical change?H2(g)O2(g)CO2(g)H2O(g)When students added 2.0 g of NaI crystals to 100. mL of Pb(NO3)2(aq), a yellow precipitate formed. After the solution was filtered, the yellow solid was dried and weighed. Data from the experiment are shown in the table above. Which of the following claims is best supported by the observations?A physical change occurred when a new yellow compound was formed.A physical change occurred when the color of the NaI solid added changed to yellow when mixed with water.A chemical change occurred when a yellow, insoluble compound with a larger mass than the original NaI formed.A chemical change occurred when covalent bonds between the yellow solid and water were broken during drying.HC2H3O2(aq) + OH?(aq) ? C2H3O2?(aq) + H2O(l)A student carried out a titration using HC2H3O2(aq) and NaOH(aq). The net ionic equation for the neutralization reaction that occurs during the titration is represented above. The NaOH(aq) was added from a buret to the HC2H3O2(aq) in a flask. The equivalence point was reached when a total of 20.0mL of NaOH(aq) had been added to the flask. How does the amount of HC2H3O2(aq) in the flask after the addition of 5.0mL of NaOH(aq) compare to the amount of HC2H3O2(aq) in the flask after the addition of 1.0mL of NaOH(aq), and what is the reason for this result?It is less because more HC2H3O2(aq) reacted with the base.It is the same because the half-equivalence point has not been reached.It is the same because all of the coefficients in the neutralization equation are 1.It is greater because HC2H3O2(aq) is a proton donor.K2SO3(aq) + 2 HNO3(aq)→2 KNO3(aq) + SO2(g) + H2O(l)According to the balanced chemical equation above, when 100.0mL of 0.100MK2SO3(aq) is mixed with 100.0mL of 0.200 M HNO3(aq) at 30°C and 1 atm, the volume of SO2 gas produced is 0.24 L. If it is assumed that the reaction goes to completion, which of the the following changes would double the volume of SO2 produced at the same temperature and pressure? (For each change, assume that the other solutions and volumes remain the same.)Using 200.0 mL of the 0.100 M K2SO3(aq), because it then becomes the reactant in excessUsing 200.0 mL of the 0.200 M HNO3(aq), because the volume of SO2 produced is inversely proportional to the number of moles at constant temperature and pressureUsing 200.0 mL of 0.100M K2SO3(aq) and 200.0 mL of 0.200 M HNO3(aq), because these are the required stoichiometric amountsUsing 400.0 mL of 0.100M K2SO3(aq) and 200.0 mL of 0.200 M HNO3(aq), because this provides the same number of moles of each reactantZn(s) + 2 HCl(aq)→ZnCl2(aq) + H2(g)When the reaction represented above proceeds, heat is produced. Which of the following best describes the reaction?It is a combustion reaction because heat is produced by the reaction.It is a double replacement reaction because 2Cl atoms are added to Zn.It is an acid-base reaction because HCl is an acid that is capable of exchanging H+.It is an oxidation-reduction reaction because zinc is oxidized and hydrogen is reduced.Which of the following best describes the process represented above that takes place when NH3 is added to water?It is a single replacement reaction in which an electron pair on N is replaced with an H atom.It is an acid-base reaction in which a proton is exchanged from H2O to NH3.It is a precipitation reaction in which NH4OH, an insoluble solid, is produced.It is an oxidation-reduction reaction in which the oxidation number of N changes from ?3 to ?4.2 Mg(s) + SiCl4(l) ? 2 MgCl2(s) + Si(s)Which of the following statements about the reaction represented above is correct?It is an oxidation-reduction reaction, and Mg is oxidized.It is an oxidation-reduction reaction, and electrons are transferred from SiCl4 to MgIt is an oxidation-reduction reaction, and the oxidation number of Cl changes from +4 to +2.It is not an oxidation-reduction reaction because none of the oxidation numbers change.C6H5COOH(aq) + NaOH(aq)→C6H5COONa(aq) + H2O(l)Which of the following identifies a conjugate acid-base pair in the reaction represented above?ACIDCONJUGATE BASEA.C6H5COOHOH－B.C6H5COOHC6H5COO－C.OH－H2OD.OH－C6H5COO－In the reaction between C5H5N(aq) and HCl(aq) represented above, C5H5N acts asa Br?nsted-Lowry basea Br?nsted-Lowry acidthe conjugate base of HClthe conjugate acid of [C5H5NH]+Based on the Br?nsted-Lowry theory of acids and bases, which of the following species can act as both a conjugate acid and a conjugate base?HS?CH3COO?H3O+NH4+5 Fe2+(aq) + MnO4?(aq) + 8 H+(aq) ? 5Fe3+(aq) + Mn2+(aq) + 4 H2O(l)Which of the following represents the oxidation half-reaction based on the balanced ionic equation shown above?Fe2+(aq) + e? ? Fe3+(aq)Fe2+(aq) ? Fe3+(aq) + e?MnO4?(aq) ? Mn2+(aq) + 5e?MnO4?(aq) + 5e? ? Mn2+(aq)Al(s)→Al3+(aq) + 3e?Sn2+(aq) + 2e?→Sn(s)Based on the half-reactions represented above, which of the following is the balanced ionic equation for the oxidation-reduction reaction between Al(s) and Sn2+(aq) ?Al(s) + Sn2+(aq)→Al3+(aq) + Sn(s) + e?3 Al(s) + 2 Sn2+(aq)→3 Al3+(aq) + 2 Sn(s)2 Al(s) + 3 Sn2+(aq)→2 Al3+(aq) + 3 Sn(s)Al(s) + Sn2+(aq) + 2e?→Al3+(aq) + Sn(s) + 3e?Zn(s) + CuSO4(aq)→Cu(s) + ZnSO4(aq)When a zinc plate is placed in an aqueous solution of copper sulfate, elemental copper forms, as represented by the equation above. Which of the following represents the reduction half-reaction of the reaction?Cu2+(aq) + 2e?→Cu(s)Cu(s)→Cu2+(aq) + 2e?Zn(s) + 2e?→Zn2?(aq)Zn(s)→Zn2+(aq) + 2e? A student combines a solution of NaCl(aq) with a solution of AgNO3(aq), and a precipitate forms. Which of the following is the balanced net ionic equation for the formation of the precipitate?Ag+(aq) + Cl?(aq)→AgCl(s)Na+(aq) + NO3?(aq)→NaNO3(s)NaCl(aq) + AgNO3(aq)→NaNO3(s) + AgCl(aq)NaCl(aq) + AgNO3(aq)→NaNO3(aq) + AgCl(s)A student combines a solution of NaCl(aq) with a solution of AgNO3(aq), and a precipitate forms. Which of the following is evidence that ionic bonds formed during the precipitation?The resulting solution is colorless.The resulting solution conducts electricity.The precipitate has a high melting point.The temperature of the solution did not change significantly during the precipitation.A student combines a solution of NaCl(aq) with a solution of AgNO3(aq), and a precipitate forms. Assume that 50.0 mL of 1.0 M NaCl(aq) and 50.0 mL of 1.0 M AgNO3(aq) were combined. According to the balanced equation, if 50.0 mL of 2.0 M NaCl(aq) and 50.0 mL of 1.0 M AgNO3(aq) were combined, the amount of precipitate formed woulddouble, because all of the coefficients are 1double, because the amount of one of the reactants was doublednot change, because all of the coefficients are 1not change, because the amount of AgNO3(aq) did not change UNIT 4 PROGRESS CHECK - FRQQuestion 1HCl(aq) + NaOH(aq)→NaCl(aq) + H2O(l)A student was given the task of titrating a 20. mL sample of 0.10 M HCl(aq) with 0.10MNaOH(aq). The HCl(aq) was placed in an Erlenmeyer flask. An equation for the reaction that occurs during the titration is given above.According to the equation for the reaction, if the amount of the reactants is halved, how does this affect the amount of H2O(l) produced in the reaction?The equation above is not written in net ionic form. Write the correct net ionic equation for the reaction.In the equation you wrote in part (b), which species is a proton acceptor?How many moles of HCl are in the 20. mL sample of 0.10 M HCl(aq)?The graph above shows the results of the titration of the 20.mL sample of 0.10MHCl(aq) with 0.10 M NaOH(aq). On the graph, draw an X to identify the location of the equivalence point of the titration.The student performs a second titration using the 0.10 M NaOH(aq) solution again as the titrant, but this time with a 20.mL sample of 0.20 M HCl(aq) instead of 0.10 M HCl(aq).The box below to the left represents ions in a certain volume of 0.10 M HCl(aq). In the box below to the right, draw a representation of ions in the same volume of 0.20 M HCl(aq). (Do not include any water molecules in your drawing.)g) On the graph in part (d), carefully draw a curve that shows the results of the second titration, in which the student titrates a 20.mL sample of 0.20MHCl(aq) with 0.10MNaOH(aq).(h) The student made observations related to the contents of the Erlenmeyer flask during the titration. Identify an observation that could have led the student to conclude that a chemical change took place during the titration. ................
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