Calculate the standard heat of formation of carbon disulphide in liquid state. Given that the standard heat of combustion of carbon (s) sulphur (s) and carbon disulphide (l) are 393.3, - 29a72 and -1108.76 kJ mol-1 respectively is:

Question

Calculate the standard heat of formation of carbon disulphide in liquid state. Given that the standard heat of combustion of carbon (s) sulphur (s) and carbon disulphide (l) are 393.3, - 29a72 and -1108.76 kJ mol-1 respectively is: (A) + 128.02 kJ mol-1 (B) -12802 kJ mol-1 (C) + 12.802 kJ mol-1 (D) -128.02 kJ mol-1

Tardigrade Admin · Accepted Answer

Use Hesss law to solve the problem.
Given :

C (s) + O_{2} (g) \to C O_{2} (g) Δ H_{1} = - 393.3 k J

... (i)

S (s) + O_{2} (g) \to S O_{2} (g) Δ H_{2} = - 293.72 k J

...(ii)

C S_{2} (l) + 3 O_{2} (g) \to C O_{2} (g) + 2 S O_{2} (g)

Δ H_{3} = - 1108.76 k J

... (iii)
Required equation

C (s) + 2 S (s) - C S_{2} (g), Δ H = ?

Multiply Eq. (ii) by 2 and add to Eq. (i)

C (s) + 2 S (s) - 3 O_{2} (g) \to C O_{2} (g) + 2 S O_{2} (g)

Δ H_{4} = - 392.3 + 2 \times - 293.72 = - 979.14 k J

...(iv)
(iv) Subtract Eq. (iii) from Eq. (iv)

C (s) + 2 S (s) \to C S_{2}

Δ H = - 979.14 - (- 1108.76) = 128.02 k J m o l^{- 1}

Q. Calculate the standard heat of formation of carbon disulphide in liquid state. Given that the standard heat of combustion of carbon $(s)$ sulphur $(s)$ and carbon disulphide $(l)$ are $393.3, - 29 a 72$ and $- 1108.76 k J m o l^{- 1}$ respectively is:

$+ 128.02 k J m o l^{- 1}$

$- 12802 k J m o l^{- 1}$

$+ 12.802 k J m o l^{- 1}$

$- 128.02 k J m o l^{- 1}$

Q. Calculate the standard heat of formation of carbon disulphide in liquid state. Given that the standard heat of combustion of carbon (s) sulphur (s) and carbon disulphide (l) are 393.3,−29a72 and −1108.76kJmol−1 respectively is:

+128.02kJmol−1

−12802kJmol−1

+12.802kJmol−1

−128.02kJmol−1

Q. Calculate the standard heat of formation of carbon disulphide in liquid state. Given that the standard heat of combustion of carbon $(s)$ sulphur $(s)$ and carbon disulphide $(l)$ are $393.3, - 29 a 72$ and $- 1108.76 k J m o l^{- 1}$ respectively is:

$+ 128.02 k J m o l^{- 1}$

$- 12802 k J m o l^{- 1}$

$+ 12.802 k J m o l^{- 1}$

$- 128.02 k J m o l^{- 1}$