[d1rtYd33dS]

About 4.00 g of hydrogen gas undergoes combustion and produces water in its liquid form state. Eventually, the temperature of the liquid is lowered to 273 K. How much energy must be released to the surroundings so that the water will be totally frozen?

[Orcio_87]

You are curious about the released energy, but first you should be curious about the water's thermodynamical properties (heat of formation and heat of phase transition).

[Darshan]

4 gm hydrogen produces 36 gm water. That is 2 moles. Enthalpy of solidification of water at 273K is 6.01KJ permol.
So answer is 2*6.01=12.02Kj energy is released.

[Orcio_87]

What about lowering the temperature to 273 K ? Does cooling not mean releasing of the heat ?

[Borek]

4 gm hydrogen produces 36 gm water. That is 2 moles. Enthalpy of solidification of water at 273K is 6.01KJ permol.
So answer is 2*6.01=12.02Kj energy is released.

Please read the forum rules, especially the part about giving final answers.

[Borek]

What about lowering the temperature to 273 K ? Does cooling not mean releasing of the heat ?

The way I read the question it asks only about the heat released after water was cooled to the freezing point.

Besides, there is not enough information to calculate anything else.