In a calorimeter (water equivalent = 40 gm) are 200 gm of water and 50 gm of ice all at 0∘C. Into this is poured 30 gm of water at 90∘C. What will be the final condition of the system?
16.25 gm ice, 266.75 gm water
Let us assume that all ice melts and warms up. Thus we will assume that T > 0.
Heat lost by water added = Heat gained by ice to melt
Heat to warm water formed from ice and water added
Heat gained by calorimeter can.
⇒ 30 × 1 × (90−T) = 50 × 80 + (50 + 200) × 1 × (T − 0) + 40 × 1 ×(T−0)
⇒ 2700−30T = 4000+250T+40T
⇒ T = −4.1∘C
Hence our assumption that T > 0 is wrong, since hot water added is not able to melt all of the ice.
Therefore the final temperature will be 0∘C
Let m = mass of ice finally left in the can.
Heat lost by water = heat gained by melting ice
⇒ 30 × 1 × (90−0) = (50−m) × 80
⇒ m = 16.25 gm
Finally there is 16.25 gm of ice and (200 + 30 + 33.75) = 266.75 gm of water at 0∘C