For the reaction:
$CH_{4(g)} + 2O_{2(g)} \to CO_{2(g)} + 2H_2O_{(l)}$;
$\Delta_r H_{300} = -212.7 \ Kcal/mol$.
The absolute value of $\Delta_r U_{300}^o$ for this reaction is ....... $Kcal/mol$ $(R = 2 \ cal/mol-K)$.

Calculate $\Delta H^{\circ}$ for the reaction, $Na_2O_{(s)} + SO_{3(g)} \longrightarrow Na_2SO_{4(s)}$, given the following reactions:
$(A) \ Na_{(s)} + H_2O_{(l)} \longrightarrow NaOH_{(s)} + \frac{1}{2}H_{2(g)} \quad \Delta H^{\circ} = -146 \ kJ$
$(B) \ Na_2SO_{4(s)} + H_2O_{(l)} \longrightarrow 2NaOH_{(s)} + SO_{3(g)} \quad \Delta H^{\circ} = +418 \ kJ$
$(C) \ 2Na_2O_{(s)} + 2H_{2(g)} \longrightarrow 4Na_{(s)} + 2H_2O_{(l)} \quad \Delta H^{\circ} = +259 \ kJ$

For the reaction $2H_{(g)} \to H_{2(g)}$,the signs of $\Delta H$ and $\Delta S$ are:

The $\Delta E^o$ of combustion of $2-$methylpropene is $-X \ kJ \ mol^{-1}$. The value of $\Delta H^o$ is

In a reversible process,under what condition does the heat exchanged become a state function?

For a certain thermochemical reaction $M \rightarrow N$ at $T = 400 \ K$,$\Delta H^{\ominus} = 77.2 \ kJ \ mol^{-1}$ and $\Delta S = 122 \ J \ K^{-1} \ mol^{-1}$,the value of $\log K$ is $ . . . . . . \times 10^{-1}$.