In a fuel cell,methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is
$CH_3OH_{(l)} + \frac{3}{2} O_{2(g)} \rightarrow CO_{2(g)} + 2H_2O_{(l)}$
At $298 \ K$,standard Gibbs energies of formation for $CH_3OH_{(l)}$,$H_2O_{(l)}$,and $CO_{2(g)}$ are $-166.2$,$-237.2$,and $-394.4 \ kJ \ mol^{-1}$ respectively. If the standard enthalpy of combustion of methanol is $-726 \ kJ \ mol^{-1}$,the efficiency of the fuel cell will be .......... $\%$.
$CH_3OH_{(l)} + \frac{3}{2} O_{2(g)} \rightarrow CO_{2(g)} + 2H_2O_{(l)}$
At $298 \ K$,standard Gibbs energies of formation for $CH_3OH_{(l)}$,$H_2O_{(l)}$,and $CO_{2(g)}$ are $-166.2$,$-237.2$,and $-394.4 \ kJ \ mol^{-1}$ respectively. If the standard enthalpy of combustion of methanol is $-726 \ kJ \ mol^{-1}$,the efficiency of the fuel cell will be .......... $\%$.
- A$87$
- B$90$
- C$97$
- D$80$
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Consider the strong electrolytes $Z_{m}X_{n}$,$U_{m}Y_{p}$ and $V_{m}X_{n}$. Limiting molar conductivity $(\Lambda^0)$ of $U_{m}Y_{p}$ and $V_{m}X_{n}$ are $250 \ S \ cm^2 \ mol^{-1}$ and $440 \ S \ cm^2 \ mol^{-1}$,respectively. The value of $(m + n + p)$ is . . . . . Given:
$Ion$ $\lambda^0 \ (S \ cm^2 \ mol^{-1})$ $U^{p+}$ $50.0$ $Y^{m-}$ $50.0$ $V^{n+}$ $60.0$ $X^{m-}$ $50.0$ $Z^{n+}$ $40.0$
$\lambda^0$ is the limiting molar conductivity of ions. The plot of molar conductivity $(\Lambda)$ of $Z_{m}X_{n}$ $vs$ $c^{1/2}$ is given below.
| $Ion$ | $\lambda^0 \ (S \ cm^2 \ mol^{-1})$ |
|---|---|
| $U^{p+}$ | $50.0$ |
| $Y^{m-}$ | $50.0$ |
| $V^{n+}$ | $60.0$ |
| $X^{m-}$ | $50.0$ |
| $Z^{n+}$ | $40.0$ |
$\lambda^0$ is the limiting molar conductivity of ions. The plot of molar conductivity $(\Lambda)$ of $Z_{m}X_{n}$ $vs$ $c^{1/2}$ is given below.
During the electrolysis of carnallite,$MgCl_2$ is decomposed and not $KCl$. This is because of
Difficult
View SolutionFind the solubility product $(K_{sp})$ of a saturated solution of $Ag_2CrO_4$ in water at $298 \ K$,if the $emf$ of the cell $Ag | Ag^{+} (\text{satd. } Ag_2CrO_4 \text{ solution}) || Ag^{+} (0.1 \ M) | Ag$ is $0.591 \ V$ at $298 \ K$.
Medium
View SolutionSolutions $A$,$B$,and $C$ of the same strong electrolyte offered resistances of $50 \ \Omega$,$100 \ \Omega$,and $150 \ \Omega$ in a given conductivity cell. The resistance observed if they are mixed in a volume proportion which is the reciprocal of their resistances and tested in the same conductivity cell would be ............. $\Omega$.
Difficult
View SolutionConsider the cell reaction at $300 \ K$: $A_{(s)} + B^{2+}_{(aq)} \rightleftharpoons A^{2+}_{(aq)} + B_{(s)}$. Its $E^{\circ}$ is $1.0 \ V$. The $\Delta_{r}H^{\circ}$ of the reaction is $-163 \ kJ \ mol^{-1}$. What is $\Delta_{r}S^{\circ}$ (in $J \ K^{-1} \ mol^{-1}$) of the reaction? $(F = 96500 \ C \ mol^{-1})$
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