The standard heat of formation $\left( {{\Delta _f}H_{298}^0} \right)$ 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 :
Answer (integer)
-192
Solution
2C(graphite)+ 3H(g) $\to$ C<sub>2</sub>H<sub>6</sub>(g)
<br><br>${\Delta _f}H$(C<sub>2</sub>H<sub>6</sub>) = 2$\Delta H$<sub>comb</sub>(C<sub>graphite</sub>) + 3$\Delta H$<sub>comb</sub>(H<sub>2</sub>)<br><br> - $\Delta H$<sub>comb</sub>(C<sub>2</sub>H<sub>6</sub>)
<br><br>= – (286$\times$2) - (393.5$\times$3) -(-1560)
<br><br>= -572 –1180.5+1560 = -192.5 kJ/mole
About this question
Subject: Chemistry · Chapter: Thermodynamics · Topic: Zeroth and First Law
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