Ms. DiOrio's AP Chemistry Classroom - Home



Unit 1 Problem SetName: ____________________________ #______AP Chemistry Block: __________Section 1: Mass Spectrometry and Average Atomic MassGiven the following data, calculate the average atomic mass of neon.Isotope% Abundance20Ne90.4821Ne0.2722Ne9.25Answer the next 3 questions given the following mass spectra:2a. Based on the mass spectrum of atom Y, which of the following statements is false? peak A and peak D come from atoms that have the same number of electronsthere are seven isotopes of atom Ypeak C comes from the most abundant isotope of atom Ypeak D comes from an atom with 4 more protons than the atom that gave peak B 2b. The identity of compound Y is: zirconium c. americium molybdenum d. einsteinium 2c. Which peak comes from an atom with the greatest number of neutrons? A c. C all peaks in the spectrum have d. D the same number of neutrons Given the mass spectrum, determine the average atomic mass of lithium.229303452461937937Sketch the mass spectrum given the following data:Section 2: Molar Mass and Percent CompositionWhat is the percent by mass of the anion in lithium periodate, LiIO4?What is the molar mass of oxalic acid?A chemist has found 2.0 moles of a mysterious compound contained 48g of carbon, 8g of hydrogen, and 64g of oxygen. What is the molecular formula of the compound?Section 3: Combustion AnalysisA 1.50 g sample of hydrocarbon undergoes complete combustion to produce 4.40 g of CO2?and 2.70 g of H2O. What is the empirical formula of this compound?A 0.2500 g sample of a compound known to contain carbon, hydrogen and oxygen undergoes complete combustion to produce 0.3664 g of CO2?and 0.1500 g of H2O. What is the empirical formula of this compound?Quinone, which is used in the dye industry and in photography, is an organic compound containing only C, H, and O. What is the empirical formula of the compound if you find that 0.105 g of the compound gives 0.257 g of CO2?and 0.0350 g of H2O when burned completely? Given a molecular weight of approximately 108 g/mol, what is its molecular formula?A carbohydrate is a compound composed solely of carbon, hydrogen and oxygen. When 10.7695 g of an unknown carbohydrate (MW = 128.2080 g/mol) was subjected to combustion analysis with excess oxygen, it produced 29.5747 g CO2?and 12.1068 g H2O. What is its molecular formula?Section 4: Gravimetric AnalysisIn an experiment, a student is given 2.94g of a mixture containing anhydrous MgCl2 and KNO3. To determine the percentage by mass of MgCl2 in the mixture, the student uses excess AgNO2(aq) to precipitate the chloride ion as AgCl(s). The student determines the mass of the AgCl precipitate to be 5.48 g. On the basis of this information, calculate each of the following. The number of moles of MgCl2 in the original mixtureThe percent by mass of MgCl2 in the original mixtureYou dissolve 0.4500 g of impure potassium chloride in water and add an excess of silver nitrate. You get 0.8402 g of insoluble silver chloride. Calculate the percent by mass of?KCl?in the original sample.A .9157 g mixture of calcium bromide and sodium bromide is dissolved in water and silver nitrate is added to the solution. If the mass of the precipitate formed is 1.6930g, what is the % by mass of sodium bromide in the original mixture?Section 5: StoichiometryA 10.0 g sample containing calcium carbonate and an inert material was placed in excess hydrochloric acid. A reaction occurred producing calcium chloride, water, and carbon dioxide. Write a balanced equation for the reaction. When the reaction was complete, 1.55 g of carbon dioxide gas was collected. How many moles of calcium carbonate were consumed in the reaction?If all the calcium carbonate initially present in the sample was consumed in the reaction, what percent by mass of the sample was due to calcium carbonate? If the inert material was only silicon dioxide, what was the mole fraction of silicon dioxide in the mixture?In fact, perhaps there had been some other material present in the original sample that was not so inert and generated a gas during the reaction. Would this have caused the calculated percentage of calcium carbonate in the sample to be higher, lower or have no effect? Justify your response. Section 6: Solutions, Concentration, and DilutionTypical blood serum is about 0.14 M NaC1. What volume of blood contains 1.0 mg NaC1? Calculate the mass of solid NaC1 that must be added to 1.50 L of a 0.100 M AgNO3 solution to precipitate all the Ag+ ions in the form of AgC1. To analyze the alcohol content of a certain wine, a chemist needs 1.00L of an aqueous 0.200 M K2Cr2O7 (potassium dichromate) solution. How much solid K2Cr2O7 must be weighed out to make this solution?What volume of 16 M sulfuric acid is needed to prepare 1.5 L of a 0.10 M H2SO4 solution?Section 7: Solubility and Net Ionic EquationsUsing the solubility rules, predict if a reaction will occur. If a precipitate forms, identify the compound.KNO3 (aq) and BaCl2 (aq)Na2SO4 (aq) and Pb(NO3)2 (aq)KOH(aq) and Fe(NO3)3 (aq)For each of the following reactions, write the molecular equation, the complete ionic equation, and the net ionic equation. Aqueous potassium chloride is added to aqueous silver nitrate to form a silver chloride precipitate plus aqueous potassium nitrate. M:CI:NI:Aqueous potassium hydroxide is mixed with aqueous iron(III) nitrate to form a precipitate of iron(III) hydroxide and aqueous potassium nitrate. M:CI:NI:Section 8: Acids/Bases and TitrationsWhat volume of a 0.100 M HC1 solution is needed to neutralize 25.0 mL of 0.350 M NaOH? In a certain experiment, 28.0 mL of 0.250 M HNO3 and 53.0 mL of 0.320 M KOH are mixed. Calculate the amount of water formed in the resulting reaction. What is the concentration of H+ and OH- ions in excess after the reaction goes to completion? A student carries out an experiment to standardize (determine the exact concentration of) a sodium hydroxide solution. To do this the student weighs out a 1.3009-g sample of potassium hydrogen phthalate (KHC8H4O4, often abbreviated KHP). KHP (molar mass 204.22 g/mol) has one acidic hydrogen. The student dissolves the KHP in distilled water, adds phenolphthalein as an indicator, and titrates the resulting solution with the sodium hydroxide solution to the phenolphthalein endpoint. The difference between the final and initial buret readings indicates that 41.20 mL of the sodium hydroxide solution is required to react exactly with the 1.3009 g KHP. Calculate the concentration of the sodium hydroxide solution. Section 9: Redox ReactionsBalance the following redox reactions in acidic solution:Mn2+ + BiO3- MnO4 + Bi3+ClO3- + Cl- Cl2 + ClO2P + Cu2+ Cu + H2PO4-PH3 + I2 H3PO2- + I-NO2 NO3- + NOBalance the following redox reactions in basic solution:MnO4- + C2O42- MnO2 + CO2Cu(NH3)42+ + S2O42- SO32- + Cu + NH3Zn + NO3- Zn(OH)42- + NH3Al + OH- AlO2- + H2 ................
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