General Chemistry Sample Exam 2 and Outline To C

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					                                General Chemistry Sample Exam 2 and Outline



    Chapter 4 Stoichiometry Calc. & formulas
  1 Chemical Equation
                                                                     Chapter 5       Gaseous State
      Type of Reactions
                                                                     1  Units of Pressure
  2 Atomic and Molc' Wt
                                                                     2 Ideal Gas Law
      AW, MW, FW
                                                                            Boyle's Law
      % Composition
                                                                            Charles Law
  3 The mole
                                                                            Avogadro's Law
  4 Empirical Formula determination
                                                                        Combined Gas Law
      Mol. Formula determination
                                                                     3 Molar mass by PV=nRT
      From Combustion Analysis
                                                                            M = m/n = (m•RT)/PV
  5 Stoichiometry problems:
                                                                     4 Dalton's Law of Partial Pressure
      Molecules to moles
                                                                            PT=Pa + Pb + ...
      Mass to moles
      Volume to moles                                                         Collecting gas over water
      Using the balance equation, molesa to molesb                   5    Stoichiometry and Gas Laws
                                                                     6    Kinetic Molecular Theory
  6 Quantitative Information
      Calculating Limiting reagents                                           KE=1/2 mu2
      Determining the amount of excess                                        urms = (3RT / M)1/2
      % yield calculations                                                    Maxwell-Boltzmann Distribution profile
  7 Solution Composition                                             7    Diffusion (mixing of gas)
      Concentrations and Molarity                                         Effusion (passage of gas through hole)
      Dilution Calculation                                           8    Real gas
  8 Properties of Solution                                                    Van der Waal equation
      Aqueous solution (Water)
      Ions in Water
      Molecules in Water
      Electrolytes: Weak electrolytes: nonelectrolytes
  9 Acid / Base
      Titration calculations and concepts
      The experimental setup
      Acid-Base Stoichiometry
  10 Ionic Equations
  11. Metathesis Reaction
      Ppt reaction and solubility table
  12 Oxidation – Reduction
      Electron transfer through single displacement
      Activity Series


Conversion information:
     System                LENGTH:                       VOLUME                   MASS                      Temperature
     English:     1 ft = 12 in                 1 gal = 4 qt              1 lb = 16 oz              T o F = 1.8T o C + 32
                  1 mile = 5280 ft             1 qt = 2 pints            1 ton = 2000 lb
                                               1 pt = 16 fl oz
     SI-          2.54 cm = 1 in               0.946 L = 1 qt            453.6 g = 1 lb                     (T o F ! 32)
     English:     1.609 km = 1 mi              3.785 L= 1 gal            28.35 g = 1 oz            T oC =
                                               29.57 mL = 1 fl oz.       1 kg = 2.205 lb                        1.8
     Misc. info                      1 mole = 6.02•1023                                    Density H2O: 1.0 g / cc
General Solubility Table:
     Soluble substances                                                  Insoluble substances
     containing -                    Exceptions                          containing -                                  Exceptions
     nitrates, (NO3-)                                                    carbonate (CO32-)
                                     None                                                                              slightly soluble
     chlorate (ClO3-)                                                    Phosphate (PO43-)
     perchlorate (ClO4-)
                                                                         chromate (CrO42-)
     Acetate (CH3COO-)
                                                                         Sulfides (S2-)
     Halogens (X-)                   Ag, Hg, Pb                          Hydroxides (OH-)                              Ca*, Sr, Ba, Alkali, NH4+
     X- = Cl-, Br-, I-                                                                                                 * marginally soluble
     Sulfates (SO42-)                Ca, Ba, Hg, Pb

     Alkali & NH4+                    None

   Soluble - dissolve, no precipitate (aq -phase)                  insoluble (or slightly soluble) - does not dissolve, precipitate forms. (s-phase)

Gas law equations:
                                               PV = nRT                                    m " P                                               L " atm
      Ideal Gas Law                                                      Denstiy(D) =            , m = mass                      R = 0.08206
                                                                                           n RT                                                mol " K
      Real Gas: vander Waal Equation              #    a " n2 &
                                                  %P +        ((V - n " b) = nRT
                                                        V2 '
                                                  %           (
                                                  $
                                                             !                                                     !
      STP                                      P = 1 atm, T = 0°C, 1 mole = 22.4 L
                                               PT = Pa + Pb + Pc + ...                                   (na + n b + n c + ...)R • T .
                                    !
      Dalton's Law of Partial Pressure                                                            PT =
                                                                                                                    VT

                                               Pa =   χ                       χ                   χ                         χ
                                                          a • PT       Pb =       b • PT      .  a = na / nT                    b = nb / nT
                                                    1                  3RT                                J
      Speed of Gas particles                   KE = mu2         urms =  !                     R = 8.314
                                                    2                   M                               mol " K
                                               ratea timeb   Mb
      Graham's Law of effusion                      =      =
                                               rateb timea   Ma
                                      !                      !             !
      Calorimetry                              qp =   ΔH = m Cs ΔT where ΔT = Tf - Ti, Cs (H2O) = 4.184 J/g•K

                                      !




_________________________________________________________________________________________________________
1   Combustion of a sulfide of bismuth compound, BixSy (50.00g) in O2 produced 45.30 g of dibismuth trioxide (Bi2O3).

    i) What are the IUPAC compound name, empirical formula and the formula weight of the bismuth sulfide (BixSy)

            compound?

    ii) What is the oxidation state of the sulfur and the bismuth in this compound?

    iii) Suppose in your combustion experiment, the BixSy compound also contained some bismuth oxide impurities, how

            would this affect the x-value in the empirical formula of BixSy (higher or lower and state your reason)?

    iv) Suppose instead of producing 45.30 g dibismuth trioxide in the final product of the combustion, 45.30 g of

            dibismuth pentaoxide is produced instead, how would this affect the y-value in the empirical formula of BixSy ?




2   Balance the following equations.
    i)      ___KOH(aq) + ___H2SO4(aq) → ___ K2SO4(aq) + ___H2O (aq)


    ii)         ___C4H14(l) + ____O2(g) → ___CO2(g) + ____ H2O(l)


    iii)        N2H4(l) + ___O2(g) → ___ NO2 (g) + ___ H2O (g)


    iv)         ___K2CO3 (aq) + ___H3PO4(aq) → ___ K3PO4 (aq) + ___CO2(g) + ____ H2O(l)


    v)          Arsenic(III)oxide + Hydrochloric acid → Arsenic(III)chloride + Dihydrogen monoxide

    vi)         Phosphorus + Bromine → Phosphorus tribromide

    vii)        Calcium carbonate decomposes to calcium oxide and carbon dioxide

    viii)       Copper(II)sulfate pentahydrate is dehydrated to ______ + ______

    Identify the type of reaction above.



3   A compound of Ca, C, N, and S was subjected to quantitative analysis and formula mass determination, and the following

    data were obtained. A 0.250 g sample was mixed with Na2CO3 to convert all of the Ca to 0.160 g of CaCO3. A 0.0268

    g sample of the compound was carried through a series of reactions until all of the S was changed to 0.0802 g of

    BaSO4. A 0.712g sample was processed to liberate all of its N as NH3, and 0.155 g NH3 was obtained. The formula

    mass was found to be 156 g/mol. Determine the empirical and molecular formulas of this compound.




4   2,4,6-Trinitrotoluene (TNT), C7H5N3O6 , can be prepared by the following two step synthesis:
    C6H6 + CH4 → C7H8 + H2
    2 C7H8 + 6 NO2 → 2 C7H5N3O6 + 3 H2


    If each step in this synthesis gives a 50% yield, how much C7H5N3O6 (TNT) in grams can be produced starting with
    780 g of benzene (C6H6) ?
5   Ethyl alcohol (booze), C2H5OH, also called grain alcohol, can be made by the fermentation of glucose, C6H12O6, which

    often comes from starch in grain:           ___ C6H12O6(aq) → ___ C2H5OH(l) + ___ 2CO2(g)

    Determine the maximum mass (theoretical yield) of ethyl alcohol, which could be produced, from 750 g of glucose. If
    150 L of CO2 is collected after the fermentation, what is the % yield. Density of CO2 (g) is 1.96 g/ L.



6   Determine which of the following will dissolve in water, then classify these as

    (s) strong electrolyte, (w) weak electrolyte or (n) non-electrolyte.

    i) NH3            ii) PbSO4         iii) KHSO4       iv) Hg2Cl2        v) HNO3           vi) NH4OH         vii) C2H5OH

    Explain your answer



7   Write the net ionic equation for any reaction that occurs upon mixing each pair of solution:

    i) silver nitrate and barium chloride

    ii) Magnesium sulfate and barium hydroxide

    iii) Hydrochloric acid and strontium hydroxide.

    iv) Iron(III) sulfide and nitric acid



8   In each of the following reaction, indicate which metal ion is the stronger oxidizing agent, that is rank each metal Zn,

    Ag and Pb in order of ease of oxidation . (i.e., Most easily oxidized > next easily oxidize > most difficult to oxidize)

    i) Zn (s) + 2AgNO3 (aq) → 2 Ag (s) + Zn(NO3)2 (aq)

    ii) Pb (s) + 2AgNO3 (aq) → 2 Ag (s) + Pb(NO3)2 (aq)

    iii) Pb (s) + Zn(NO3)2 (aq) → NR.




9   Some sulfuric acid is spilled on a lab bench. Sprinkling some sodium bicarbonate on to the sulfuric acid can neutralize

    it. The reaction produces sodium sulfate, carbon dioxide and water.

    i) Write the molecular, ionic and net ionic equation and balance the equation (include the phases).

    ii) What is the limiting reagent and how much remains if 35 ml of 6.0 M sulfuric acid is spilled and 50 grams of sodium

        bicarbonate is added ?

    iii) What is the mass of carbon dioxide gas (g) that is produced ?

    iv) How many molecules of carbon dioxide are produced ?

    v) If 5.00 ml of water is actually produce, what is the % yield of water ?

    vi) How many oxygen atoms are involved in this reaction ?

    vii) If all the liquid is evaporated, what is the mass of sodium sulfate that is produced ?

    viii) What is the concentration of sodium sulfate if 20.0 g sodium sulfate is dissolved in the 5.00 ml water?
10   Consider 100 formula units (or molecules) of each:

     a) Tin(IV) hypoiodite                     b) carbon tetraiodide                 c) cadmium iodite

     i) Which compound contains the largest mass of iodine? How much is this mass in grams?

     ii) Which contains the greatest mass of metal atoms? For a 100 unit sample, what is the total of these metal atoms ?

     iii) If all three of these substances were mixed and added to water, calculate the total number of ions in solution.




11   Balance the following equations and then answer the questions below.

                 Potassium permanganate is added to hydrochloric acid to produce

                          chlorine gas, potassium chloride, manganese(II) chloride and water.

     i) How many moles of hydrochloric acid are required to react with 45 grams of potassium permanganate ?

     ii) How many chlorine molecules will be produced using 5.0 moles of potassium permanganate ?

     iii) To produce 55.0 grams of manganese(II) chloride, what mass of hydrochloric acid is required?

     iv) How many moles of water will be produce when 7.00 moles of potassium permanganate is consumed ?

     v) What is the maximum weight of chlorine that can be produced by reacting 35.0 g of potassium permanganate with

         45.0 g of hydrochloric acid ?

     vi) In v (above), if the %yield of chlorine in the reaction is 76%, how much (g) chlorine was actually recovered ?




12   Oxygen gas (2.00 mol) is introduce into a 44.8 L rigid container at 1.0 atm and 25°C. What amount of oxygen (in moles)

     is necessary to increase the temperature to 50°C if the pressure remains constant.




13   An analysis of a gas yielded an empirical formula of CH2F. If the rate of effusion for Helium is 4.06 times as fast as
     this gas,    rHe           ,
                          = 4.06 what is the molecular formula of this chlorofluorocarbons.
                 rCH 2F



14   Hydrogen can be prepared in the laboratory by the reaction of zinc and hydrochloric acid. The reaction is :

     Zn(s) + 2HCl(aq) --> ZnCl2(aq) + H2(g).       If 44.8 L of H2 is produce from the reaction, how much zinc was used,

     assume excess acid and STP conditions P = 1.0 atm, and T = 0°C.
15   Nitric oxide (NO) reacts with molecular oxygen as follows:

              2NO (g) + O2(g) →        2NO2(g)
                                                                                           NO                           O2
     Initially NO and O2 are separated as shown below. When the valve is             4.00 L                         2.00 L
                                                                                     0.500 atm                      1.00 atm
     opened, the reaction quickly goes to completion. Determine what gases

     remain at the end and calculate their partial pressure. Assume that the

     temperature remains constant at 25° C.



16   For each of the following pairs determine which gas has the largest Urms. Explain your reasoning.

     a) Ne (g) or N2 (g) at room temperature

     b) H2O (g) at 500°C, or NH3 (g) at 600 K

     c) CH4 (g) at 212 °F or NO2 (g) both at 373 K



17   Below are statements that may or may not explain how a hot air balloon rises when the air in the balloon is heated. If

     the statement is true, explain why it is consistent with the kinetic molecular theory, if the statement is not true,

     rewrite the statement such that it is consistent with the kinetic molecular theory.

     a) The average kinetic energy of the molecules increases and the collisions between the molecules and the walls of the

     balloon make it rise.

     b) The pressure of the gas inside the balloon increases, pushing up on the balloon.

     c) The gas expands, forcing some of tit to escape from the bottom of the balloon, and the decrease in the density of

     this gas lifts the balloon.

     d) The balloon expands, causing it to rise.

     e) The hot air rising inside the balloon produces enough force to lift the balloon.



18   The Kinetic molecular theory is a model, which tries to explain the behavior of gases at the molecular level. In the end

     though, it is just that, a model, and as such it breaks down under certain conditions and must be modified.

     In this essay,

     (a) discuss the KMT and how it can be used to explain the following:

     (i) why pressure increases with an increase in temperature at constant volume.

     (ii) why the Urms for a gas increases with temperature.

     (iii) why gases fill their container and why gases are compressible but solids and liquids are not.



     Then discuss how this model breaks down under certain conditions, and what corrections must be applied.

     (b) What two assumptions of the Kinetic molecular theory becomes invalid, and under what conditions does this occur?

     (c) How is the ideal gas law modified in order to account for these inconsistencies.