CHEMISTRY 1211 TEST #3 (100 pts)     5/xx/03                Name __________________

GPC - Dunwoody -     Dr. Kim 's Section                                   Calculator & Model _________________

Use a Scantron Form (4pts each). Do not blacken a bubble if your choice is F or G.

1mi=1.609km; 1ft=0.3048m; 1lbs=453.6g; 1gal=3.785L; 1mL=1cm³; g=9.807m/s²;
1cal=4.184J; 1atm=760mmHg=10,334mmH₂O=101,325Pa=14.7psi; Density(Hg)=13.60g/mL; m_e=9.109x10^-31kg R=0.08206L^.atm/(K^.mol)=8.315J/(K^.mol); c=2.9979x10⁸m/s; h=6.626x10^-34J^.s; R_H=2.180x10^-18J; 1L^.atm=101.3J.

Note: This test is for  "The Gasesous State" and "Thermo chemistry".

1. Which gas is colorless, odorless, and toxic? (A) CO₂, (B) NO₂, (C) NH₃, (D) H₂S, (E) CO.

2. Which gas has the highest density?              (A) CO₂, (B) NO₂, (C) NH₃, (D) H₂S, (E) CO.

3. Which gas moves the fastest at STP?          (A) CO₂, (B) NO₂, (C) NH₃, (D) H₂S, (E) CO.

4. Which is NOT a unit of pressure? (A)kg/(m^2.s²), (B)kg/(m^.s²), (C) inHg, (D) psi(=lb/in²), (E)Pa.

5. Avogadro's Law tells us that 1 mole of H₂ gas must have the same (A) mass, (B) volume, (C) density, (D) number of atoms as 1 mole of CO₂ or any other gas has.

6.  Find a pressure (due to water and atmosphere) at a depth which is 300 ft under a sea surface.
    (A) 1, (B)5, (C)8, (D) 9, (E) 10 atm. (Density of sea water=1.03 g/cm³)

7. Convert an average atmospheric pressure of metro-Atlanta from millimeters of mercury column to millimeters of water column:  735 mmHg = (A) 10, (B) 100, (C) 1000, (D) 10,000, (E) 100,000 mmH₂O.

8.  You want to drink a water from a well with a narrow opening. A very thin long straw is given. A barometer reads 755 torr. At what lung's pressure can you drink it? A(832), B(740), C(712), D(682) torr, E(None of these). (Depth between your mouth and the water surface is 1 yards).

9. Find a molar volume of a gas at 100^oC. A(22.4), B(24.5), C(30.6), D(62.8), E(89.6) L.

10. The partial pressures of N₂ , O₂ and Ar in the normal air(1 atm, dry) are 0.78, 0.21 and 0.01 atm,
respectively, because their (a) mass %, (b) mole(or volume) %, are 78, 21 and 1 each. When the air is compressed to one half of its original volume at the same temperature, partial pressure of O₂ will be ca. (c) 0.4, (d) 0.20, (e) 0.1 atm. A(a,c), B(a,d), C(a,e), D(b,c), E(b,d), F(b,e).

11. Find the average molar mass of a fully wet air. A(28.5), B(28.6), C(28.7), D(28.8), E(28.9) g/mol. (This question is for an open book exam).

12. According to the Graham's Law, CO₂ gas will diffuse/effuse
    A(0.5), B(0.8), C(1.2), D(1.5), E(2.1) times faster than SO₂ gas at a same condition.

13. A balloon with 5.41dm³ (=1.43gal) of He gas at 24^oC and 101.5 kPa is heated to 35^oC.
      If the new pressure is 92.8kPa, what is the new volume(L)?
    A(4.76), B(5.12), C(5.28), D(6.14), E(24.8) dm³.

14.  Dry air is (a) denser (or heavier), (b) lighter, than humid air. Density of air is directly proportional to (c) square root, (d) first power of its molar mass. Therefore, it  is easier to hit a home run in a humid whether than a a dry weather if other conditions are the same. A(a,c), B(a,d), C(b,c), D(b,d).

15. Find a density of air in a hot Summer day in Atlanta at 35^oC and 29inHg(=736mmHg).
    (          ) g/L. (M_air=29g/mol).

16. The rms speed of H₂ molecules at 4 K is about A(one tenth), B(the same), C(10 times),
D(100 times), E(1,000 times) of/as a speed of a jet air plane which is about 500 MPH.

17. The mean-free-path, an average distance a gas molecule can travel without colliding  to another molecule, of a gas is ca. (a) 0.1 mm, (b) 0.1 km at STP: it (c) increases, (d) decreases, with decreasing pressure. A(a,c), B(a,d), C(b,c), D(b,d).

18. According to the Kinetic Molecular Theory, the average (a) Momentum, (b) Kinetic Energy, of a gas molecule is (c) directly, (d) inversely proportional to its absolute temperature.
A(a,c), B(a,d), C(b,c), D(b,d).

19. Real gases behave as if they are ideal gas under conditions of (a) higher, (b)lower, temperature and (c) higher, (d) lower, pressure. A(a,c), B(a,d), C(b,c), D(b,d), E(-).

20. A mass of gas vapor with a volume of 200mL at 99^oC and 745mmHg is measured to be 0.540g. The compound must be A(CH₄), B(C₂H₆), C(C₆H₆), D(C₆H₁₂), E(C₈H₁₈) .

21.How many moles of gas are in a gas sample occupying 0.750 L at 0.316 atm and 25 ^oC?
    A(58.0), B(7.36), C(0.463), D(0.0969). E(0.00969) moles.

22.  In what season air molecules bombard onto your skin at an RMS velocity of ca. 525 m/s
(to make you feel either cold, warm, or hot). Human skin can be a speedometer for the gases.
A(Winter), B(Spring or Fall), C(Summer), D(Cant' telll).

23. Equal Volume of ammonia, NH₃, and Nitrogen (N₂) at the same temperature and presssure have the same
A(masses), B(density), C(number of atoms), D(number of molecules), E(mass percent nitrogen).

24. Given two containers of the same size at the same pressure and temperature, one containing SO₂ molecules and the other containing  CH₄ molecules , which of the following comparison is correct?
A (The kinetic energies of the SO₂   and CH₄  molecules are the same.)
B (The mass of the matter in each containers are the same.)
C (The average speeds of  the two kinds of the molecules are the same.)
D (The number of  CH₄  molecules is four times as great as the number of  SO₂  molecules.)
E (The number of  CH₄  atoms  ii each container is the same.)

25.  What volume of Cl₂ in liters can be prepared from 3.0 L of HCl gas and 3.0 L of O₂ gas if all volumes are measured at the same temperature and pressure? The equation for the reaction is

        4 HCl  +  O₂   ->     2H₂O  +  2 Cl₂     (all gases)

A(1.5 L), B(2.0 L), C(2.5 L), D(3.0 L), E(6.0 L).

26. . What gases are third most abundant in air with 0%(dry) and 100%(fully wet) humidity?
A(Ar, CO_2, ), B(CO₂, Ar), C(CO₂ , H₂O), D(Ar, H₂O), E(Ar, Ar), respectively.

27.  Convert an average atmospheric pressure,  640mmHg, of Denver  from to millimeters of mercury column to inches of a mercury  column:
       640 mmHg = (A) 25, (B) 26, (C) 27, (D) 28, (E) 29 inHg.

28. When solid ammonium nitrite undergo decomposition, only gases are produced, according to the equation
            NH₄NO_2(s)   -> N_2(g) + 2 H₂O_(g)
what is the total volume of the gases produced at 546 K and 1.00 atm of a pressure when 128 grams of ammonium nitrite undergo es the above reaction?
      A(89.5), B(134.), C(179), D(269), E(403) L.

29. At standard conditions, 4.16 liters of a gas weighed 6.32 grams.
      I.  What's the molar mass? A(26), B(30), C(34), D(36), E(48) g/mol.
     II.  The gas must be          A(C₂H₂),  B(NO),  C(PH₃),  D(HCl),  E(CH₃SH).

30. If 2.00 L of xenon at 300 torr and 4.00 L of argon at 600 torr are put in a 6.00 L of container, what will be the final pressure be ?
A(3,000 torr), B(900 torr), C(500 torr), D(480 torr), E(450 torr).

Thermochemistry starts from Here.

32.  The most dominant form of internal energy(U) in a balloon with He gas in it at room temperature is
    A(Gravitational Potential Energy), B(Rotational Kinetic Energy), C(Vibrational Kinetic Energy),
    D(Translational Kinetic Energy), E(Radiant Energy).

33. A gas expands in volume from 1.0 L to 3.0L at constant temperature. Calculate the work done by the gas if it expands against a constant pressure of 1.0 atm

  A(0.10 kJ), B(0.20 kJ), C(0.30 kJ), D(0.40 kJ), E(0.50 kJ).

34. You wish to heat water to make coffee. How much heat (J) must be used to raise the temperature
    of a half gallon(1.89kg) of tap water (enough for 10 cup) from 20 to 96^oC(near the ideal brewing temperature).
    Assume that it requires 4.184 J to raise temperature of 1.00g of tap water by 1.00^oC.
    A(0.60 kJ), B(6.0 kJ), C(60 kJ), D(600kJ), E(6,000kJ).

35.  Ehthalpy(H) of a system is defined as
A(Sum of kinetic energy of all particles in a system),
B(Sum of potential energy of all particles in a system),
C(Sum of kinetic energy & potential energy of all particles in a system),
D(Sum of kinetic energy & potential energy of all particles minus pressure  times volume of a system).
E(Sum of kinetic energy & potential energy of all particles  plus pressure  times volume of a system).

36. The sign of DH for the process  H₂O(g) →  H₂O(l) is

A (positive and the process is endothermic), B (negative and the process is endothermic),

C (positive and the process is exothermic),  D (negative and the process is exothermic).

37. Given the thermochemical equation:        N_2(g) + 3H_2(g) → 2NH_3(g); DH= -91.8 kJ
    How much heat will be  evolved when 1,480 kg of ammonia is produced at a constant pressure?.

   A(1x10⁶), B(2x10⁶), C(3x10⁶), D(4x10⁶) kJ

38. 0.562g of graphite is burned in a calorimeter at 25.00^oC at 1atm to reach temperature of 25.89^oC.
    C_(graphite) + O_2(g) → CO_2(g) Heat capacity of the calorimeter is 20.7 kJ/^oC.
    Find DH^o_f (kJ/mol) for CO_2(g). A(0.86), B(-221), C(221), D(-393), E(393).

39. Which of the following has a standard enthalpy of formation (DH_f^o ) value of a zero?

  A(Na⁺(g)), B(Na⁺(aq)), C(Na(g)), D(Na(l)), E(Na(s)).

40. Which reaction is being referred to when the standard enthalpy of formation,  DH_f^o (MgCl_2(s))= -641.8 kJ/mol,  of  magnesium chloride is spoken ?

A. Mg_(s)   +  2Cl_(g)     →     MgCl_2(s),    
B. Mg_(l)    +  2Cl_(g)     →    MgCl_2(s),  
C. Mg_(s)   +   Cl_2(l)     →     MgCl_2(s),   
D. Mg_(s)   +   Cl_2(g))   →     MgCl_2(s),    
E. Mg²⁺_(aq)+ 2Cl^-_(aq) →     MgCl_2(s).    

41.  Given the thermochemical equation:    4 NH_3(g) + 5O_2(g) → 4 NO(g) + 6 H₂O_(g);  DH^o= -906.0 kJ
    Find DH for the following reaction:         NO(g) + 3/2 H₂O_(g)   →  NH_3(g) + 5/4 O_2(g)

   A(3624),  B(226.5), C(453.0), D(-1816), E(-453.0)  kJ

42.   Manganase metal can be obtained by reducing manganase dioxide with aluminum. Find DH^o  for the reaction:
       4 Al_(s)+ 3 MnO_2(s)   →  2 Al₂O_3(s)+ 3 Mn_(s)
Given the following enthalpy of formation (DH)data:
        2Al_(s) +  3/2O_2(s)  →   Al₂O_3(s) ;    DH^o=-1,676kJ
         Mn_(s) + O_2(s)       →   MnO_2(s) ;    DH^o=-521kJ
 A(-1,789), B(-1,155), C(0.00), D(+1,155), E(+1789) kJ.

44. How much heat is generated from the neutralization reaction above?
 A(2.134), B(21.34), C(213.4), D(2,123), E(21,134) kJ

45. Find the enthalpy change (DH_rxn) for the neutralization reaction.  Assume that the heat capacity and the density of the final solution are same as those of H₂O.
A(54), B(55), C(56), D(-54), E(-55), F(-56) kJ/mol.

46.  Find the heat generated ( -DH^o_comb) when 1 mole of methane is burned;
    CH_4(g)+ 2O_2(g) → CO_2(g)+ 2H₂O_(g) knowing that H^o_f are -74.9, -393.5 & -241.8kJ/mol
    for CH_4(g), CO_2(g) & H₂O_(g) respectively.

A(890.2 kJ),  B(802.2 kJ), C(980.2 kJ), D(568.5 kJ), (568.5 MJ).
47. Find energy required to heat 40. gal of water from 20^oC to 60^oC.   

A(6.06 kJ), B(6.06 MJ), C(25.3 kJ), D(25.3MJ).

48. If the efficiency of the  burner is 50%, how many   mol and  kg  of CH₄ are needed?

A(63 mol, 1.01 kg), B(32 mol, 0.505 kg) , C(16 mol, 0.252 kg), D(8.8mol, 0.126 kg).

49.  What's the volume, in L at 1 atm and 25^oC,  of the  CH₄ are needed?

A(3080), B(1540), C(770), D(385) L.

50. If the gas is contained in a10 gal container at 25^oC, what will be the pressure in psi?

A(120), B(230), C(600), D(2230) psi.

                                                 Some Additional Practice Problems

1. An average human breathe 12 times a minute. During each breath 500 mL  of air molecules are inhaled and exhaled. Estimate a total mass of air in tons which Wolfgang Amadeus Mozart breathed(inhaled) during his life time of 35 years.
 About   A(1), B(10) , C(100), D(1,000), E(10,000) tons.

2. From the normal atmospheric pressure and the surface area of Earth (radius=4,000 mi), estimate the total mass of air contained in the entire atmosphere.
            A(10¹⁵), B(10¹⁸), C(10²¹), D(10²⁴), E(10²⁷) tons.

3. What fraction of atmospheric molecules was breathed (inhaled) by Mozart during his life?
            A(10^-10), B(10^-12), C(10^-14), D(10^-16), E(10^-18), approximately.

                                              *             *             *             *             *
4.  Find the mass, in mg, of H₂ gas produced by the reaction:
                2HCl_(aq)+Zn_(s)  →  ZnCl_2(aq)+H_2(g)
56.0 mL of gas is collected over water at 22^oC ant 765 mmHg total pressure. (Vapor pressure of water at 22^oC is 19.8mmHg).
      A(11.1), B(11.4), C(12.9), D(14.1), E(8.4), F(4.8) mg.

                                             *             *             *             *             *

5. When sodium hydrogen carbonate (NaHCO₃, baking soda) is heated it decomposes to Na₂CO₃, CO₂, and H₂O. Write the balanced equation for this reaction. What volume (in liters) of CO₂ gas at 75^oC and 756mm Hg will be produced from 26.8g of baking soda?
 

6. Calculate a RMS velocity of the air molecules at the room temperature, 25^oC . 
       A(400), B(450), C(500), D(550), E(600) m/s.

7.  How many moles of air molecules contained in a room (20 ft x 30 ft x 10 ft) in Atlanta (i.e., 740 mmHg) at the room temperature?    (              ) mols.

8. Then estimate total kinetic energy of all air molecules in this room using the rms velocity calculated above. (E_k=(1/2) mv²)
A( 26 J), B(26 kJ), C(26 MJ), D(26 GJ), E(26 PJ).

9. Find a potential energy of 50 gal water on a dam of 100 m height.
      A( 0.185), B(1.85), C(18.5), D(185), E(1,850) kJ.

10. Which energy is the largest?

     A(Potential energy of 50 gal water on a dam of 100m height),
     B(Kinetic energy of all of gases in this room, 20ft x 30 ft x 10 ft),
     C(Energy of 1 mol of UV light of =200nm),
     D(30.6kJ=1g of coal), E(Energy required to vaporize 1 mol of water at 100^oC: 40.7 kJ/mol).
     F(Energy required to break all of H-H bonds in 1 mol of H₂ gas: 432kJ/mol).

(rev.  08/03/05, 10/22/01, 11/05/98, MHK)