Hi there, I have some serious problems with a couple of questions. Need help for exam revision. 1.1 The problem statement, all variables and given/known data A 2kg chunck of ice at -10Celsius is added to 5kg of water at 45Celsius. What is the final temperature of the system? 1.2 Relevant equations specific heat capacity of ice - 2100 Jkg-1K-1 specific heat capacity of water - 4190 Jkg-1K-1 latent heat of fusion for ice - 334 000 Jkg-1 1.3 The attempt at a solution Using formula E=mC(change in)T E1 - 2 x 2100 x 10 = 42000J E2 - 2 x 334 000 = 668 000J E3 - 668 000 + 42 000 = 710 000J E4 - 710 000=5 x 4190 x (change in)T T=33.89Celsius, so final temperature is 45-33.89=11.11, but the correct answer has to be 7.9Celsius. 2.1 The problem statement, all variables and given/known data A cylinder with a piston contains 0.2 kg of water at 100 Celsius. What is the change in internal energy of the water when it is converted to steam at 100Celsius at a constant pressure of 105 Nm-2? 2.2 Relevant equations latent heat of vaporisation of water - 2.26 x 106 Jkg-1 density of water - 1000 kgm-3 density of steam - 0.6 kgm-3 2.3 The attempt at a solution Using (change in) U=(change in)Q - P x (change in)V U=internal energy, Q=heat, P=pressure, V=volume Change in heat is 2.26 x 106 x 0.2 = 452 000 J Can't manage more :(. Supposed answer is 418.7 kJ.