hot metal + water = Tf??? Yet again I find i am stumped by having no clue as to what I did in this incredibly easy problem. Simple right? 1 = water 2 = copper m1c1 delta T1 = -m2c2 delta T2 This simplifies to... m1= (-m2c2 delta T2)/(c1 delta T1) which is... (-(110*.2*(25.6-82.4)))/((4.18*(25.6-22.3)) = 95.8533g Computer says i'm wrong and it slapped me I then did the lazy way and calculated the energy required to lower the copper's temperature. With that, I manually figured out how much water there was and got the exact same answer. Where am I going wrong here?