4. Calculate the total heat required to convert 23.6 g of ice at -27 ºC to steam at 121 ºC. Hint: Calculation involves more than 1 step. 5.How much heat, in kJ, is needed to convert 12.8 g of ice at -18 ºC to steam at 118 ºC? Hint: Calculation involves more than 1 step.

Consider the reduction reactions and their equilibrium constants. cu+(aq)+e−↽−−⇀cu(s)pb2+(aq)+2e−↽−−⇀pb(s)fe3+(aq)+3e−↽−−⇀fe(=6.2×108=4.0×10−5=9.3×10−3 cu + ( aq ) + e − ↽ − − ⇀ cu ( s ) k =6.2× 10 8 pb 2 + ( aq ) +2 e − ↽ − − ⇀ pb ( s ) k =4.0× 10 − 5 fe 3 + ( aq ) +3 e − ↽ − − ⇀ fe ( s ) k =9.3× 10 − 3 arrange these ions from strongest to weakest oxidizing agent.