Home
Class 11
CHEMISTRY
The standard enthalpies of combustion of...

The standard enthalpies of combustion of `C_(6)H_(6)(l), C("graphite") and H_(2)(g)` are respectively `-3270 kJ "mol"^(-1), -394 kJ "mol"^(-1)` and `-286 kJ "mol"^(-1)`. What is the standard enthalpy of formation of `C_(6)H_(6)(l)` in kJ ` "mol"^(-1)`?

A

`-48`

B

`+48`

C

`-480`

D

`+480`

Text Solution

Verified by Experts

The correct Answer is:
B
(i) `C_(6)H_(6)(l) + 15/2O_(2)(g) to 6CO_(2)(g) + 3H_(2)O(l) DeltaH = -3270 kJ "mol"^(-1)`
(ii) `C(gr) + O_(2)(g) to CO_(2)(g) DeltaH = -394 kJ "mol"^(-1)`
(iii) `H_(2)(g) + 1/2O_(2)(g) to H_(2)O(l) DeltaH = -286 kJ "mol"^(-1)`
The required equation is
(iv) `6C(gr) + 3H_(2)(g) to C_(6)H_(6)(l),DeltaH` = ?
Multiply eq.(ii) by 6 and eq(ii) by 3 and adding we get :
(v) `6C(gr) + 15/2O_(2)(g) + 3H_(2)(g) to 6CO_(2)(g) + 3H_(2)O(l), DeltaH = -3222 kJ`
Subtract eq.(i) from eq.(v)
`6C(gr) + 3H_(2)(g) to C_(6)H_(6)(l) DeltaH = + 48 kJ "mol"^(-1)`.
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • THERMODYNAMICS

    MODERN PUBLICATION|Exercise Competition File (Matching Type Questions)|2 Videos

  • THERMODYNAMICS

    MODERN PUBLICATION|Exercise Competition File (Matrix Matching Type Questions)|4 Videos

  • THERMODYNAMICS

    MODERN PUBLICATION|Exercise Higher Order Thinking Questions|16 Videos

  • STRUCTURE OF ATOM

    MODERN PUBLICATION|Exercise Unit Practice Test|13 Videos

Similar Questions

Explore conceptually related problems

The molar enthalpies of combustion of C_(2)H_(2)(g), C("graphite") and H_(2)(g) are -1300,-394 , and -286 kJ mol^(-1) , respectively. The standard enthalpy of formation of C_(2)H_(2)(g) is

The enthalpy of combustion of methane, graphite and dihydrogen at 298K are -890.3 kJ mol^(-1), -393.5 kJ mol^(-1) and -285.8 kJ mol^(-1) respectively. Calculate enthalpy of formation of methane gas.

Knowledge Check

  • The standard enthalpies of combustion of C_(6)H_(6) (l) ,C ( graphite) and H_(2)(g) are respectively -3270 kJ mol^(-1), - 394kJ mol^(-1) and -286 kJmol^(-1) . What is the standard enthalpy of formation of C_(6)H_(6)(l) in kJ mol^(-1) /

    A
    `- 48`
    B
    `+48`
    C
    `-480`
    D
    `+480`

  • The standard enthalpies of combustion of C_(6)H_(6(l)),C_(("graphite"))and H_(2(g)) are respectively -3270 kJmol^(-1), -394 kJ mol^(-1) and - 286 kJ mol^(-1) . What is the standard enthalpy of formation of C_(6)H_(6(l)) in kJ mol^(-1)

    A
    `- 48`
    B
    `+ 48`
    C
    `- 480`
    D
    `+ 480`

  • If the enthalpies of formation of C_3H_8(g), CO_2(g) and H_2O(l) at standard conditions are -104 kJ mol^-1, -394 kJ mol^-1 and -286 kJ mol^-1 respectively then the standard anthalpy of combustion of 66 g of C_3H_8(g) will be

    A
    `- 2222 kJ`
    B
    ` - 2500 kJ`
    C
    `- 784 kJ`
    D
    `- 3333 kJ`

    • Similar Questions

    Explore conceptually related problems

    The standard enthalpy of formation of CO_(2)(g) , H_(2)O(l) and glucose (s) at 25^(@)C are -400.0 kJ mol^(-1),-300.0 kJ mol^(-1) and -1300.0 kJ mol^(-1) respectively. The standard enthalpy of combustion per gram of glucose at 25^(@)C is

    The standard enthalpies fo formation of CO_(2) (g), H_(2) O (1) , and glucose (s) at 25^(@)C are - 400 kJ mol^(-1), - 300 kJ mol^(-) , and - 1300 kJ mol^(-1) , respectively. The standard enthalply of combustion per gram of glucose at 25^(@)C is

    The enthalpy of combustion of methane, graphite and dihydrogen at 298 K are -890.3 kJ mol^(-1) , -393.5 kJ mol^(-1) and -285 kJ mol^(-1) respectively. Enthalpy of formation of CH_(4)(g) will be (a) -74.8 kJ "mol"^(-1) (b) -52.27 kJ "mol"^(-1) (c) + 74.8 kJ "mol"^(-1) (d) +52.26 kJ "mol"^(-1)

    The standard enthalpies of formation of CO_(2)(g), H_(2)O(l) and glucose (s) at 25^(@)C are -400 kJ/mol, -300 kJ/mol and -1300 kJ/mol, respectively. The standard enthalpy of combustion per gram of glucose at 25^(@)C is :

    The enthalpy of combustion of methane, graphite and dihydrogen at 298 K are, -890.3 kJ mol^(-1) , –393.5 kJ mol^(-1) and –285.8 kJ mol^(-1) respectively. Enthalpy of formation of CH_(4) (g) will be

    Home
    Profile