Two 20.0-g ice cubes at - 20.0 °c are placed into 205 g of water at 25.0 °c. assuming no energy is transferred to or from the surroundings, calculate the final temperature, tf, of the water after all the ice melts.

Taking in account that ice cubes are made with water, both substance has the same heat propieties, so then only needs to consider mass and temperatures to reach a solution and use a weighted average of the initial temperatures, 2 ice of 20 gr. at - 20ºC or 253.15º K and 205 gr of water at 25ºC or 298.15ºK, then final temperature, Tf is: Tf = ((2*20*253.15) + (205*298.15)) / (2*20+205) = 290.8ºK or 17.65ºC The final temperature after ice melts decrease till 17.65ºC