How many grams of ice are needed to cool 250 ml of water from 75 degrees celcius to 5 degrees celcius?

Answer 1

Note the correct spelling of celsius.
Heat gained by ice + heat gained by melted water + heat lost by original water = 0

[mass ice x heat fusion] + [mass melted ice x specific water x (Tfinal-Tinitial)] + [mass 250mL water x specific heat water x (Tfinal-Tinitial)] = 0
Solve for mass ice (and melted ice). I think something like 200 g ice is necessary but that is an aproximation.