Table 2:

Experimental standard enthalpies of processes involving ${\mathrm{B}\mathrm{r}}_2$ and HBr at the reference temperature $T=298.15\mathrm{K}$ considered by CODATA^a,b

Eq. No.38	Process	$-\frac{{\Delta }_{\text{r}}{H}_{\text{m}}^{\circ }}{\mathrm{kJ}\cdot {\mathrm{mol}}^{-1}}$	Reference
71	$0.5{\mathrm{H}}_2\left(\mathrm{g}\right)+0.5{\mathrm{B}\mathrm{r}}_2\left(\mathrm{g}\right)=\mathrm{H}\mathrm{B}\mathrm{r}\left(\mathrm{g}\right)$	51.92 ± 0.45	50
72	${\mathrm{C}\mathrm{l}}_2\left(\mathrm{g}\right)+2\mathrm{H}\mathrm{B}\mathrm{r}(\mathrm{a}\mathrm{q}$, diss. $)={\mathrm{B}\mathrm{r}}_2(\mathrm{l})+2\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q}$, diss. $)$	See text	51,52
73	${\mathrm{C}\mathrm{l}}_2\left(\mathrm{g}\right)+2\mathrm{H}\mathrm{B}\mathrm{r}(\mathrm{a}\mathrm{q}$, diss. $)={\mathrm{B}\mathrm{r}}_2(\mathrm{l})+2\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q}$, diss. $)$	91.54 ± 0.64	53,54
75	$\mathrm{H}\mathrm{B}\mathrm{r}\left(\mathrm{g}\right)=\mathrm{H}\mathrm{B}\mathrm{r}(\mathrm{a}\mathrm{q}$, diss. $)$	85.144 ± 0.060	45
78	$0.5{\mathrm{H}}_2\left(\mathrm{g}\right)+0.5{\mathrm{B}\mathrm{r}}_2\left(\mathrm{l}\right)=\mathrm{H}\mathrm{B}\mathrm{r}(\mathrm{a}\mathrm{q}$, diss. $)$	120.37 ± 0.80c	55,56
79	${\mathrm{B}\mathrm{r}}_2\left(\mathrm{l}\right)={\mathrm{B}\mathrm{r}}_2\left(\mathrm{a}\mathrm{q}\right)$	0.83 ± 0.20	57
80	${\mathrm{B}\mathrm{r}}_2\left(\mathrm{l}\right)={\mathrm{B}\mathrm{r}}_2\left(\mathrm{a}\mathrm{q}\right)$	2.17 ± 0.20d	58
81	$\mathrm{H}\mathrm{B}\mathrm{r}\left(\mathrm{g}\right)=\mathrm{H}\mathrm{B}\mathrm{r}(\mathrm{a}\mathrm{q}$, diss. $)$	86.01 ± 1.00c	59
82	${\mathrm{B}\mathrm{r}}_2\left(\mathrm{a}\mathrm{q}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)=2\mathrm{H}\mathrm{B}\mathrm{r}($ aq,diss. $)$	240.94 ± 0.15	56,60

^aThe following reference values at $T=298.15\mathrm{K}$ recommended by CODATA³⁸ were used in the regression: ${\text{Δ}}_{\text{f}}{H}_{\text{m}}^{\circ }\left({\text{Br}}_2(\text{g})\right)=30.91\text{kJ}\cdot {\text{mol}}^{-1}$, ${\text{Δ}}_{\text{f}}{H}_{\text{m}}^{\circ }(\text{HCl}(\text{aq},\text{diss}.))={\text{Δ}}_{\text{f}}{H}_{\text{m}}^{\circ }\left({\text{Cl}}^{-}(\text{aq}.)\right)=-167.08\text{kJ}\cdot {\text{mol}}^{-1}$, $S_{\text{m}}^{\circ }\left({\text{H}}_2(\text{g})\right)=130.68\text{J}\cdot {\text{K}}^{-1}\cdot {\text{mol}}^{-1}$, $S_{\text{m}}^{\circ }\left({\mathrm{Br}}_2(1)\right)=152.51\text{J}\cdot {\text{K}}^{-1}\cdot {\text{mol}}^{-1}$, $S_{\text{m}}^{\circ }\left({\text{Br}}^{-}(\text{aq})\right)=82.55\text{J}\cdot {\text{K}}^{-1}\cdot {\text{mol}}^{-1}$, and $S_{\text{m}}^{\circ }(\text{HBr}(\text{g}))=198.70\text{J}\cdot {\text{K}}^{-1}\cdot {\text{mol}}^{-1}$

^bValues obtained by the weighted least-squares regression: ${\text{Δ}}_{\text{f}}{H}_{\text{m}}^{\circ }\left({\text{Br}}_2(\text{aq})\right)=-(0.97\pm 0.40)\text{kJ}\cdot {\text{mol}}^{-1}$, ${\text{Δ}}_{\text{f}}{H}_{\text{m}}^{\circ }(\mathrm{HBr}(\text{g}))=-(35.85\pm 0.28)\text{kJ}\cdot {\text{mol}}^{-1}$, and ${\text{Δ}}_{\text{f}}{H}_{\text{m}}^{\circ }(\mathrm{HBr}(\text{aq},\text{diss}.))={\text{Δ}}_{\text{f}}{H}_{\text{m}}^{\circ }\left({\text{Br}}^{-}(\text{aq})\right)=-(120.98\pm 0.24)\text{kJ}\cdot {\text{mol}}^{-1}$

^cObtained from the standard Gibbs energy using the reference values from footnote $a$

^dassumed incorrect in this work