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  1. #1

    Aug 2011
    -
    2,564

    Energy Changes in Chemical Reactions
    ɡ . : ء .
    .

    :
    12-3-: q= mcT .
    2- 12-1 : .

    - .
    - .
    - .
    - .
    - .
    - .

    - 4.18J/g.0C ϡ

    1- T=48-25= 230C m=95.4g q=849J c=?
    q= mcT
    849J=(95.4g)c(230C)
    c= 0.387 J/g.0C
    2- .
    3- c=3.5J/g.0C m=4kg q=250kJ T=?
    q= mcT
    250kJ=(4kg)( 3.5J/g.0C) T
    T= 17.90C

    :
    12-3-: .
    1-12-2: .

    - .
    - (3-3).
    - : ɿ ӡ ɿ ӿ

    ( ) ( ) ( ).

    :

    12-3-: .
    12-3-: H .
    2-12-2: .
    2-12-1: .
    3-12-2: .

    - .
    - .
    - . : ( ) ( ).
    - .
    - H0.
    - (1).

    H
    ɡ :
    H=H()-H()
    H=H( )-H( )

    1- ء .
    2- .

    (1) ( )
    : 25 .
    : 5-6 .

    :
    1- 8g .
    2- .
    3- .


    1- : q= mcT T c=4.18 J/g.0C m=8g
    2- ( )
    3- .
    4- NH4NO3 NH4Cl
    5- .


    ) . E (
    ( ) ɡ (w) (q ) ∆E=q-W
    q=W .
    (P) (V) P∆V P∆V ء H ( ) PV H=E+PV ∆H=∆E+P∆V+V∆P ∆E ∆E=q-w w=P∆V :
    ∆H= q-P∆V+P∆V+V∆P V∆P ∆H= q + ∆H= q .

    ѡ ѡ 208kJ .

    :
    12-3-: .
    4-12-2-: .

    - H .
    - ( ) .
    - ɡ .

    C4H10(g)+13/2O2(g) → 4CO2(g)+5H2O(g) H= -5742kJ/mol
    C4H10(g)+13/2O2(g) → 4CO2(g)+5H2O(g) + 5742kJ/mol

    :

    12-3-: .
    12-3-: .
    2-12-1: .
    1-12-3: .
    3-12-2: .
    3-12-3: .

    - .
    - .
    - H=nHX .
    - q H .
    - .
    - .

    - (2) .

    1- H=nHfr
    = 100Kg(1000g/Kg)(mol/18g)
    =5.5x103 mol
    H=(5.5x103 mol)(-6.03kJ/mol)
    = -3.35x104kJ
    2- - H=-114kJ
    - = 2
    =-114kJ/2
    -57kJ/mol
    (2)
    : 30 .
    : 5-6 .
    ..

  2. #2

    Aug 2011
    -
    2,564

    :

    :
    1- .
    2- .
    3- .

    1- C2 H5OH(l) +3O2(g) → 2CO2(g) +3H2O(l)
    2- (q1 )= X T
    = X 0.387J/g.0C
    0.387J/g.0C
    (q2)= q2=mcT
    = q1+q2

    .
    3- . : ɡ ɡ .

    (1) ( )
    Molar Enthalpy of Neutraliza
    : .
    :
    .

    1- HCl(aq)+NaOH(aq) → NaCl(aq)+ H2O(l)
    2- T= T2-T1 T2 (+) T1 .

    3- =4.18J/g.0C
    = 40g T ȡ
    q= mcT ɡ :
    (HCl )= x
    = 20x1/1000=0,02mol
    (NaOH)
    =
    0.02mol
    4- : ɡ ɡ .

    : .
    : .
    : .
    : (0.1M ) (0.1M) (2 ) ߡ (Styrofoam ) 100mL (2).
    :
    1- 25mL ݡ .
    2- 25mL .
    3- ӡ ء .


    1- :
    Ý- ∆T = .
    ȝ- =4.18 J/g.0C .
    - 50g .
    - : q= mcT
    2- .
    :

    Ag+(aq) + Cl-(aq) → AgCl(s)

    Ag+= (Cl-)
    = 0.1 x 25/1000= 0.0025mol (Ag+)
    H= q -66kJ

    3- ȿ .
    . : ɡ ɡ .
    2- ɿ .
    -66kJ/mol

    :

    12-3-: ɡ .
    12-3-: .
    2-12-1: .
    1-12-3: .
    3-12-2: .


    - ̿
    - .
    - .

    (3):
    : 20 .
    : 5-6 .
    :
    1- .
    2- ӡ ɡ .
    1g of water=1mL of water

    1- = - .
    2- q=?, m= (water+ice),c=4.18J/g.0C, ∆T= T2-T1
    q= mcT ɡ + .
    3- ɡ .



    . (∆Hfus ) : = Hliquid-Hsolid ∆Hfus ɡ . (18g ) 6.0kJ/mol 40kJ ɡ . ɡ (CO2 ) (∆Hsub ) :
    ∆Hsub= Hvap-Hsolid Hsolid :
    Hsolid= Hliquid - ∆Hfus
    :
    ∆Hsub= Hvap (Hliquid -∆Hfus) Hvap Hliquid (∆Hvap ) :
    ∆Hsub= ∆Hvap+ ∆Hfus


    ѡ :

    :
    12-3-: ɡ .
    1-12-3: .

    2-12-2: .
    3-12-2: .

    - H0f.
    - .
    - ( ) ( ) ɡ () .
    -
    :
    H0rxn = nH0f( ) - nH0f( )
    - .

    C6H6(g)+15/2O2(g)→6CO2(g) +3H2O(l)
    H0rxn = nH0f( ) -nH0f( )
    -3273kJ/mol= [(6x-393.5)+(3x-285.8)]-[0+(2x C6H6)]
    HC6H6= 54.6kJ/mol

    :
    12-3-: .
    1-12-1: .
    4-12-2: .

    - .
    - .
    - .
    - .

    1- (2 ) (6 ) (8 ) :
    H0=4016kJ 2C3H7OH(l)+9O2(g) → 6CO2(g)+8H2O(l)
    6C(graphite)+ 6O2(g) 6CO2(g) H0=-2361kJ/mol
    8H2(g)+4O2(g) 8H2O(l) H0=-2286.4kJ/mol

    6C(graphite)+8H2(g)+O2(g)2C3H7OH(l) H0= 631.4kJ/mol
    2- H0 -850.2kJ/mol .

    3-
    -106.3kJ/mol= C2H5Br +(52.2+-36.4)
    H0f (C2H5Br)= -122.1kJ/mol

    4- q= mcT
    m= 13.7+85.0=98.7g, c=4.18J/g.0C,
    ∆T=19.7-23.4=-3.70C
    q= -1526kJ
    :
    =13.7/331
    =0.04mol
    Hsol= -38162.3kJ/mol
    ..

  3. #3

    Jul 2011
    -
    15,678

    :

    ..
    ...


  4. #4
      Eiman
    Jul 2011
    -
    14,750

    :


    .......

  5. #5

    Jul 2012
    5,302

    :



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