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Review Session-6

# Review Session-6 - REVIEW SESSION‐ 6 ...

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Unformatted text preview: REVIEW SESSION‐ 6  Chemical Kine6cs  14.3) You perform a series of experiments for the reac7on AB+C and ﬁnd  that the rate law: Rate=k[A]x. Determine the value of x in each of the following  cases: (a) There is no rate  change when [A] is tripled (b) The rate increases by  a factor of 9 when [A] is tripled (c) When [A] is doubled, the rate increases by a  factor of 8   14.3) You perform a series of experiments for the reac7on AB+C and ﬁnd  that the rate law: Rate=k[A]x. Determine the value of x in each of the following  cases: (a) There is no rate  change when [A] is tripled (b) The rate increases by  a factor of 9 when [A] is tripled (c) When [A] is doubled, the rate increases by a  factor of 8   (a) No change in rate, x=0, Rate = k [A]0  zero order reac7on.    14.3) You perform a series of experiments for the reac7on AB+C and ﬁnd  that the rate law: Rate=k[A]x. Determine the value of x in each of the following  cases: (a) There is no rate  change when [A] is tripled (b) The rate increases by  a factor of 9 when [A] is tripled (c) When [A] is doubled, the rate increases by a  factor of 8   (a) No change in rate, x=0, Rate = k [A] 0  zero order reac7on in A.    (b) Rate  increases by 9 7mes when [A] is tripled  2nd order in A   14.3) You perform a series of experiments for the reac7on AB+C and ﬁnd  that the rate law: Rate=k[A]x. Determine the value of x in each of the following  cases: (a) There is no rate  change when [A] is tripled (b) The rate increases by  a factor of 9 when [A] is tripled (c) When [A] is doubled, the rate increases by a  factor of 8   (a) No change in rate, x=0, Rate = k [A] 0  zero order reac7on in A.    (b) Rate  increases by 9 7mes when [A] is tripled  2nd order in A   (c) Rate  increases by 8 7mes when [A] is doubled  3rd order in A   14.16) A ﬂask charged with 0.1 mol of A and allowed to react to form B  according to the hypothe7cal gas phase reac7on A(g)B(g). The following  data are collected: (a) calculate the number of B at each 7me in the table (b)  Calculate the average disappearance of A for each 40 sec 7me interval, in units  of mol/s.  Time  Moles of A  0  0.1  40  0.067  80  0.045  120  0.030  160  0.020  14.16) A ﬂask charged with 0.1 mol of A and allowed to react to form B  according to the hypothe7cal gas phase reac7on A(g)B(g). The following  data are collected: (a) calculate the number of B at each 7me in the table (b)  Calculate the average disappearance of A for each 40 sec 7me interval, in units  of mol/s.  Time  Moles of A  Moles of B  0  0.1  0  40  0.067  0.033  80  0.045  0.055  120  0.030  0.070  160  0.020  0.080  14.16) A ﬂask charged with 0.1 mol of A and allowed to react to form B  according to the hypothe7cal gas phase reac7on A(g)B(g). The following  data are collected: (a) calculate the number of B at each 7me in the table (b)  Calculate the average disappearance of A for each 40 sec 7me interval, in units  of mol/s.  Moles of B  ΔMoles of A  Time  Moles of A  0  0.1  0  ‐  40  0.067  0.033  ‐0.033  80  0.045  0.055  ‐0.022  120  0.030  0.070  ‐0.015  160  0.020  0.080  ‐0.010  14.16) A ﬂask charged with 0.1 mol of A and allowed to react to form B  according to the hypothe7cal gas phase reac7on A(g)B(g). The following  data are collected: (a) calculate the number of B at each 7me in the table (b)  Calculate the average disappearance of A for each 40 sec 7me interval, in units  of mol/s.  Moles of B  ΔMoles of A  Rate (‐ΔMoles of A/s)  Time  Moles of A  0  0.1  0  ‐  ‐  40  0.067  0.033  ‐0.033  8.3X10‐4  80  0.045  0.055  ‐0.022  5.5X10‐4  120  0.030  0.070  ‐0.015  3.8X10‐4  160  0.020  0.080  ‐0.010  2.5X10‐4  14.20) For each of the following gas phase reac7ons, write the rate expression  in terms of the appearance of product or disappearance of reactant?  (A) 2H2O(g) 2H2(g)+ O2(g)  (B) 2SO2(g)+O2(g)  2SO3(g)  (C) 2NO(g)+2H2(g)  N2(g)+2H2O (g)  14.20) For each of the following gas phase reac7ons, write the rate expression  in terms of the appearance of product or disappearance of reactant?  (A) 2H2O(g) 2H2(g)+ O2(g)  Rate = ‐Δ[H2O]/2Δt = Δ [H2]/2Δt = Δ [O2]/Δt  (B) 2SO2(g)+O2(g)  2SO3(g)  Rate = ‐Δ[SO2]/2Δt = ‐Δ [O2]/Δt = Δ [SO3]/2Δt  (C) 2NO(g)+2H2(g)  N2(g)+2H2O (g)  Rate = ‐Δ[NO]/2Δt = ‐Δ [H2]/2Δt = Δ [N2]/Δt= Δ [H2O]/2Δt   14.21) Consider the combus7on of hydrogen gas: 2H2+O22H2O. If hydrogen  is burning at the rate of 0.85 mol/s, what is the rate of consump7on of oxygen?  What is the rate of forma7on of water vapor?  Rate = Δ[H2O]/2Δt = ‐Δ [H2]/2Δt = ‐Δ[O2]/Δt  14.21) Consider the combus7on of hydrogen gas: 2H2+O22H2O. If hydrogen  is burning at the rate of 0.85 mol/s, what is the rate of consump7on of oxygen?  What is the rate of forma7on of water vapor?  Rate = Δ[H2O]/2Δt = ‐Δ [H2]/2Δt = ‐Δ[O2]/Δt  Rate of burning of H2, ‐Δ[H2] = 0.85 mol/s  Consump7on of Oxygen = ‐Δ[O2]/Δt = ‐Δ [H2]/2Δt  = 0.85/2 = 0.425 mol/s  14.21) Consider the combus7on of hydrogen gas: 2H2+O22H2O. If hydrogen  is burning at the rate of 0.85 mol/s, what is the rate of consump7on of oxygen?  What is the rate of forma7on of water vapor?  Rate = Δ[H2O]/2Δt = ‐Δ [H2]/2Δt = ‐Δ[O2]/Δt  Rate of burning of H2, ‐Δ[H2] = 0.85 mol/s  Consump7on of Oxygen = ‐Δ[O2]/Δt = ‐Δ [H2]/2Δt  = 0.85/2 = 0.425 mol/s  Rate of forma7on of water = Δ[H2O]/2Δt = ‐Δ [H2]/2Δt = 0.85 mol/s.  14.21)(b) The reac7on 2NO+Cl22NOCl is carried out in a closed vessel. If  par7al pressure of NO is decreasing at the rate of 23 torr/min, what is the rate  of change of total pressure of the vessel?  Rate = ‐ΔPNO/2Δt = ‐Δ PCl2/Δt = ΔPNOCl/Δt  ‐ΔPNO/Δt = ‐23 torr/min  ΔPCl2/Δt = ‐23/2 = ‐12 torr/min   ΔPNOCl/Δt = +23 torr/min  ΔPT/Δt = ‐23‐12+23 = ‐12 torr/min  14.24)Consider a hypothe7cal reac7on between A, B and C that is ﬁrst order in  A, zero order in B and second order in C.  (a) Write rate law for the reac7on  (b) How does rate law changes when [A] is doubled and other reactants held  constant?   (c) How does rate law changes when [B] is tripled and other reactants held  constant?   (d) How does rate law changes when [c] is tripled and other reactants held  constant?   (d) By what factor does the rate change when the concentra7ons of all  reactants tripled?  14.24)Consider a hypothe7cal reac7on between A, B and C that is ﬁrst order in  A, zero order in B and second order in C.  (a) Write rate law for the reac7on  Rate = k[A][C]2  (b) How does rate law changes when [A] is doubled and other reactants held  constant?   (c) How does rate law changes when [B] is tripled and other reactants held  constant?   (d) How does rate law changes when [c] is tripled and other reactants held  constant?   (d) By what factor does the rate change when the concentra7ons of all  reactants tripled?  14.24)Consider a hypothe7cal reac7on between A, B and C that is ﬁrst order in  A, zero order in B and second order in C.  (a) Write rate law for the reac7on  Rate = k[A][C]2  (b) How does rate law changes when [A] is doubled and other reactants held  constant?   Rate doubles  (c) How does rate law changes when [B] is tripled and other reactants held  constant?   (d) How does rate law changes when [c] is tripled and other reactants held  constant?   (d) By what factor does the rate change when the concentra7ons of all  reactants tripled?  14.24)Consider a hypothe7cal reac7on between A, B and C that is ﬁrst order in  A, zero order in B and second order in C.  (a) Write rate law for the reac7on  Rate = k[A][C]2  (b) How does rate law changes when [A] is doubled and other reactants held  constant?   Rate doubles  (c) How does rate law changes when [B] is tripled and other reactants held  constant?   Rate: No Change  (d) How does rate law changes when [c] is tripled and other reactants held  constant?   (d) By what factor does the rate change when the concentra7ons of all  reactants tripled?  14.24)Consider a hypothe7cal reac7on between A, B and C that is ﬁrst order in  A, zero order in B and second order in C.  (a) Write rate law for the reac7on  Rate = k[A][C]2  (b) How does rate law changes when [A] is doubled and other reactants held  constant?   Rate doubles  (c) How does rate law changes when [B] is tripled and other reactants held  constant?   Rate: No Change  (d) How does rate law changes when [c] is tripled and other reactants held  constant?   Rate increases by 9 7mes  (d) By what factor does the rate change when the concentra7ons of all  reactants tripled?  14.24)Consider a hypothe7cal reac7on between A, B and C that is ﬁrst order in  A, zero order in B and second order in C.  (a) Write rate law for the reac7on  Rate = k[A][C]2  (b) How does rate law changes when [A] is doubled and other reactants held  constant?   Rate doubles  (c) How doesrate law changes when [B] is tripled and other reactants held  constant?   Rate: No Change  (d) How does rate law changes when [c] is tripled and other reactants held  constant?   Rate increases by 9 7mes  (d) By what factor does the rate change when the concentra7ons of all  reactants tripled?  Rate increases by 27 7mes  14.28) Reac7on is in ethylalcohol at 330K: C2H5Br (alc)+ OH‐ (alc)C2H5OH (l) +Br‐(alc) is ﬁrst order in each ethylbromide and hydroxide ion. When [C2H5Br] is  0.0477M and [OH]‐ is 0.1M, the rate of disappearance of ethylbromide is  1.7X10‐7M/s.  (a) What is the value of rate constant?  (b) What are the units of rate constant?  (c) How would the rate of disappearance of ethylbromide change if the  solu7on diluted by adding an equal volume of ethylalcohol solu7on?  14.28) Reac7on is in ethylalcohol at 330K: C2H5Br (alc)+ OH‐ (alc)C2H5OH (l) +Br‐(alc) is ﬁrst order in each ethylbromide and hydroxide ion. When [C2H5Br] is  0.0477M and [OH]‐ is 0.1M, the rate of disappearance of ethylbromide is  1.7X10‐7M/s.  (a) What is the value of rate constant?  ‐Δ[C2H5Br]/Δt= Rate =k[C2H5Br][OH]‐  Rate = 1.7X10‐7 M/s  k= rate/[C2H5Br][OH]‐ =  1.7X10‐7/(0.0477)(0.1) = 3.6X10‐5  (b) What are the units of rate constant?  (c) How would the rate of disappearance of ethylbromide change if the  solu7on diluted by adding an equal volume of ethylalcohol solu7on?  14.28) Reac7on is in ethylalcohol at 330K: C2H5Br (alc)+ OH‐ (alc)C2H5OH (l) +Br‐(alc) is ﬁrst order in each ethylbromide and hydroxide ion. When [C2H5Br] is  0.0477M and [OH]‐ is 0.1M, the rate of disappearance of ethylbromide is  1.7X10‐7M/s.  (a) What is the value of rate constant?  ‐Δ[C2H5Br]/Δt= Rate =k[C2H5Br][OH]‐  Rate = 1.7X10‐7 M/s  k= rate/[C2H5Br][OH]‐ =  1.7X10‐7/(0.0477)(0.1) = 3.6X10‐5  (b) What are the units of rate constant?  k= (M/s)/ (M)(M) = M‐1s‐1  (c) How would the rate of disappearance of ethylbromide change if the  solu7on diluted by adding an equal volume of ethylalcohol solu7on?  14.28) Reac7on is in ethylalcohol at 330K: C2H5Br (alc)+ OH‐ (alc)C2H5OH (l) +Br‐(alc) is ﬁrst order in each ethylbromide and hydroxide ion. When [C2H5Br] is  0.0477M and [OH]‐ is 0.1M, the rate of disappearance of ethylbromide is  1.7X10‐7M/s.  (a) What is the value of rate constant?  ‐Δ[C2H5Br]/Δt= Rate =k[C2H5Br][OH]‐  Rate = 1.7X10‐7 M/s  k= rate/[C2H5Br][OH]‐ =  1.7X10‐7/(0.0477)(0.1) = 3.6X10‐5  (b) What are the units of rate constant?  k= (M/s)/ (M)(M) = M‐1s‐1  (c) How would the rate of disappearance of ethylbromide change if the  solu7on diluted by adding an equal volume of ethylalcohol solu7on?  Adding equal volume of ethylalcohol reduces the concentra7on of  reactants by a factor of two  rate(R') = (1/2) (1/2)(R) = 1/4R  New rate (R') will be ¼ th of orizinal rate (R).   Using the table 14.2, (a) determine the rate law, (b) rate constant and  (c) rate of the reac7on when the concentra7ons of both reactants  raised to [0.1M]  Using the table 14.2, (a) determine the rate law, (b) rate constant and  (c) rate of the reac7on when the concentra7ons of both reactants  raised to [0.1M]  (a)  Rate = k [ NH 4 + ][ NO2− ] € Using the table 14.2, (a) determine the rate law, (b) rate constant and  (c) rate of the reac7on when the concentra7ons of both reactants  raised to [0.1M]  (a)  Rate = k [ NH 4 + ][ NO2− ] € (b) From the table, Ini7al rate = 5.4 X 10‐7M/s  [NH4]+ = 0.0100 M, [NO2]‐ = 0.200 M   5.4X10‐7 M/s  k  =   = 2.7 X 10‐4 M‐1s‐1  [0.01 M] [0.20M]  Using the table 14.2, (a) determine the rate law, (b) rate constant and  (c) rate of the reac7on when the concentra7ons of both reactants  raised to [0.1M]  (a)  Rate = k [ NH 4 + ][ NO2− ] € (b) From the table, Ini7al rate = 5.4 X 10‐7M/s  [NH4]+ = 0.0100 M, [NO2]‐ = 0.200 M   5.4X10‐7 M/s  k  =   = 2.7 X 10‐4 M‐1s‐1  [0.01 M] [0.20M]  (c) Rate = [2.7 X 10‐4M‐1s‐1][0.10M] [0.10M] = 2.7 X 10‐6 M/s    14.36) (a) For a second order reac7on, what quan7ty, when graphed vs 7me,  will yield a straight line? (b) how do the half lives of ﬁtst and second order  reac7ons diﬀer?  14.36) (a) For a second order reac7on, what quan7ty, when graphed vs 7me,  will yield a straight line? (b) how do the half lives of ﬁtst and second order  reac7ons diﬀer?  (a)  A graph of 1/[A] Vs 7me yields a straight line for second order reac7on  (b)  Half life of a ﬁrst order reac7on independent of ini7al concentra7on of  reactant [A]0, t½ = 0.693/k  (c)  Half life of a second order reac7on dependent of ini7al concentra7on of  reactant [A]0, t½ = 1/k[A]0  14.38) Molecular iodine [I2(g)], dissociates into iodine atoms at 625K with a  ﬁrst order rate constant of 0.271s‐1. (a) What is the half life of this reac7on?  (b) If you start with 0.05M of I2 at this temperature, how much will remain  aler 5.12s assuming that the iodine atoms do not recombine to form I2?  14.38) Molecular iodine [I2(g)], dissociates into iodine atoms at 625K with a  ﬁrst order rate constant of 0.271s‐1. (a) What is the half life of this reac7on?  (b) If you start with 0.05M of I2 at this temperature, how much will remain  aler 5.12s assuming that the iodine atoms do not recombine to form I2?  (a) For ﬁrst order reac7on: t ½ = 0.693/k = 0.693/0.271s‐1= 2.56 s  14.38) Molecular iodine [I2(g)], dissociates into iodine atoms at 625K with a  ﬁrst order rate constant of 0.271s‐1. (a) What is the half life of this reac7on?  (b) If you start with 0.05M of I2 at this temperature, how much will remain  aler 5.12s assuming that the iodine atoms do not recombine to form I2?  (a) For ﬁrst order reac7on: t ½ = 0.693/k = 0.693/0.271s‐1= 2.56 s  (b) For ﬁrst order reac7on: ln[A]t= ‐kt + ln[A]0  [A]0 = 0.05, k=0.271, t= 5.12  ln[I2]t = ‐(0.271X 5.12)+ ln(0.05)      = ‐1.387 ‐2.995 = ‐4.39   [I2]t = exp(‐4.39) = 0.0125M  14.38) Molecular iodine [I2(g)], dissociates into iodine atoms at 625K with a  ﬁrst order rate constant of 0.271s‐1. (a) What is the half life of this reac7on?  (b) If you start with 0.05M of I2 at this temperature, how much will remain  aler 5.12s assuming that the iodine atoms do not recombine to form I2?  (a) For ﬁrst order reac7on: t ½ = 0.693/k = 0.693/0.271s‐1= 2.56 s  (b) For ﬁrst order reac7on: ln[A]t= ‐kt + ln[A]0  [A]0 = 0.05, k=0.271, t= 5.12  ln[I2]t = ‐(0.271X 5.12)+ ln(0.05)      = ‐1.387 ‐2.995 = ‐4.39   [I2]t = exp(‐4.39) = 0.0125M  Another way: 2.56sec is the half life for this reac7on  2.56sec  2.56sec  0.05M of I2 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐> 0.025M of I2 ‐‐‐‐‐‐‐‐‐‐‐> 0.0125M of I2  (Total: 5.12sec)  ...
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