First slide

Batteries

Question

Standard free energies of formation (in kJ/ mol) at 298 K are – 237.2, – 394.4 and – 8.2 for H₂O(l), CO₂(g) and pentane (g), respectively. The value of $E_{cell}^{0}$ for the pentane-oxygen fuel cell is :

Moderate

Solution

${C_5}{H_{12}}_{\left( g \right)} + 8{O_{2\left( g \right)}} \to 5C{O_{2\left( g \right)}} + 6{H_2}{O_{\left( l \right)}}$

$\Delta {G^o} = G_{pro}^o - G_{rea}^o = \left[ {6\left( { - 273.2} \right) + 5\left( { - 394.4} \right)} \right] - \left[ { - 8.2} \right] = - 3387kJ$
Calculation of 'n' value
decrease in oxidation state of Oxygen atom = 2
Total decrease in oxidation state of Oxygen atom = 2 x 16 =32
$\Delta {G^o} = - nFE_{cell}^o \Rightarrow E_{cell}^o = \frac{{ - \Delta {G^o}}}{{nF}} = \frac{{3387}}{{32 \times 96.5}} = + 1.09V$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App