If 2.00 moles of lithium bromide are dissolved in 1000.0 grams of water at 25.0 °C, what is the final temperature of the water, assuming that all solutions have the same heat capacity as pure water (4.184 J/g-K)?

Respuesta :

Explanation:

The dissociation of lithium bromide is given by the thermochemical equation as,

[tex]LiBr\rightarrow Li^+\ +\ Br^-\ \Delta H=-48.83\ kJ/mol[/tex]

Number of moles, n = 2 moles

Molar mass of Lithium bromide is 86.845 g/mol

For the two moles, the heat released is, [tex]Q=2\times 48.83=97.66\ kJ=97660\ J[/tex]

For 2 moles of Lithium Bromide, [tex]m=2\times 86.845=173.69\ g[/tex]

Initial temperature, [tex]T_i=25^{\circ}C=298\ K[/tex]

The heat capacity is given by :

[tex]Q=mc\Delta T[/tex]

[tex]Q=mc(T_f-T_i)[/tex]

[tex]T_f[/tex] is the final temperature

[tex]T_f=\dfrac{Q}{mc}+T_i[/tex]

[tex]T_f=\dfrac{97660\ J}{173.69\ g\times 4.184\ J/g-K}+298\ K[/tex]

[tex]T_f=432.38\ K[/tex]

So, the final temperature of the water is 432.38 k. Hence, this is the required solution.