Chemistry Homework Help!

Question

Suppose you can transfer the heat -134663.9 kJ with 100% efficiency to 1.00 L of water initially at 25°C. After the heat transfer takes place, what are the state and temperature of the water? ( there is 1.000 kg of each element of the equation 2Al + 3CuO ---> Al₂O₃ + Cu. Standard enthalpy is -1204.1 kJ).

Answer 1

There seems to be two different, unrelated things here, Alysa. I will work on the one related to the heat transfer. Consider also that you have way too many digits for a practical, working problem, but I'll go with what you have.

q = mcΔT {Note that the - sign merely let's you know that heat is released. It dopes not enter into this calculation. Also, since the density of water is 1.00 g/mL, 1.00 L = 1000 g (or 1.00 x 10³ g in keeping with 3 sig figs)}

134663.9 kj = [(1.00 x 10³ g) (4.184 J/g ^oC x 1 kJ/1 x 10³ J) (T_f - 25^oC)]

Solving for T_f results in a value of ~ 1290 K. This would make the state of the water a gas since water boils at ~373 K.