( 0,1173 kg . 2,2 . 103 J kg-1 K-1 . -31°C ) + ( 0,1173 kg . 4,18 . 103 J kg-1 K-1 . 87°C ) + ( 0,1173 kg . 4,18 . 103 J kg-1 K-1 ) = smeltwarmte smeltwarmte=J kg-1 = rs
What are the units of the 2.2 4.18 ? Also, it appears you need to convert the C degrees to Kelvin.