QJEEM20Ch5aaf: JEE Main 2020 Chemistry - Class 11 JEEM20Ch5aaf Solution: The standard heat of formation ( Δ f H 298 0 ) of ethane (in…

Question

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The standard heat of formation

(Δ_{f} H_{298}^{0})

of ethane (in kj/mol), if the heat of combustion of ethane, hydrogen and graphite are - 1560, -393.5 and -286 Kj/mol, respectively is :

Accepted Answer

2C(graphite)+ 3H(g)

\to

C₂H₆(g)

Δ_{f} H

(C₂H₆) = 2

Δ H

_comb(C_graphite) + 3

Δ H

_comb(H₂)

-

Δ H

_comb(C₂H₆)

= – (286

\times

2) - (393.5

\times

3) -(-1560)

= -572 –1180.5+1560 = -192.5 kJ/mole

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