When 2 moles of C2H6 are completely burnt 3120 kJ of heat is liberated- Calculate the heat of formation- Hf- for C2H6- Given Hf0 for CO2g and H2Ol are -395 and -286 kJ respectively-

2C_2H_6+7O_2⟶ #10;4CO_2+6H_2O #10; Δ H_reaction= 3120 kJ #10; Δ H_reaction=(Δ #10;H_f^o)_products (Δ H_f^o)_reactants #10; ∴ ...

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Standard XII

Chemistry

Heat of Formation

When 2 mole...

Question

When $2$ moles of $C_{2} H_{6}$ are completely burnt $3120 k J$ of heat is liberated. Calculate the heat of formation,
$△ H_{f}^{\circ}$ for $C_{2} H_{6}$ . Given $△ H_{f}^{0}$ for $C O_{2} (g)$ and $H_{2} O (l)$ are $- 395$ and $- 286 k J$ respectively.

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Solution

$2 C_{2} H_{6} + 7 O_{2} ⟶ 4 C O_{2} + 6 H_{2} O$

$Δ H_{r e a c t i o n} = - 3120$ $k J$

$Δ H_{r e a c t i o n} = (Δ H_{f}^{o})_{p r o d u c t s} - (Δ H_{f}^{o})_{r e a c t a n t s}$

$∴ - 3120 = - [2 \times Δ H_{f}^{o} (C_{2} H_{6}) + 7 \times Δ H_{f}^{o} (O_{2})] + [4 \times Δ H_{f}^{o} (C O_{2}) + 6 \times Δ H_{f}^{o} (H_{2} O)]$

$⟹ - 3120 = - 2 \times Δ H_{f}^{o} (C_{2} H_{6}) + 7 \times 0 - 4 \times 395 - 6 \times 286$

$⟹ 2 \times Δ H_{f}^{o} (C_{2} H_{6}) = 3120 - 1580 - 1716$

$⟹ 2 \times Δ H_{f}^{o} (C_{2} H_{6}) = - 176$

$⟹ Δ H_{f}^{o} (C_{2} H_{6}) = - 88$ $k J$

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Q. When

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moles of

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are completely burnt,

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When 2 mole of $C_{2} H_{6}$ are completely burnt, 3129 KJ of heat is liberated. Calculate the heat of formation of $C_{2} H_{6} . △ H_{f}$ for $C O_{2} & H_{2} O$ are -395 KJ and -286 KJ respectively.

Q. When

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C_{2} H_{6}

are completely burnt,

3129 k J

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C_{2} H_{6}

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When 2 moles of C2H6 are completely burnt 3120 kJ of heat is liberated. Calculate the heat of formation,△H∘f for C2H6. Given △H0f for CO2(g) and H2O(l) are −395 and −286 kJ respectively.

When $2$ moles of $C_{2} H_{6}$ are completely burnt $3120 k J$ of heat is liberated. Calculate the heat of formation,
$△ H_{f}^{\circ}$ for $C_{2} H_{6}$ . Given $△ H_{f}^{0}$ for $C O_{2} (g)$ and $H_{2} O (l)$ are $- 395$ and $- 286 k J$ respectively.