Q1 a ∆ M = M1 - M2 ∆M = 0.068kg - 0.024kg = 0.044kg Q1b E = m L f E = L f , 15,000 J = 341,000 J/kg ∆M 0.044kg
Q2a ∆ M = M1 - M2 ∆M = 0.152kg - 0.144kg = 0.008kg E = m L v E = L v 18400 J = 2,300,000 J/kg ∆M 0.008kg
Q3a. Heat transferred from water: E = m c θ = 0.12 x 4200 x (15-9) = 3024 J Q3b. Heat transferred to newly formed water warming from 0C to 9 C: E = m c θ = 0.008 x 4200x 9 = 302 J Q3c. Energy to melt 0.008kg ice = 3024J - 302 J = 2722J Energy to melt 1 kg ice = 2722 J = 340,250 J/kg 0.008 kg
Q4 Energy required to vaporise 0.1kg water :E = m L f E = 0.1 x 2.25 x106 E = 2.25 x105 J Power (W) = energy transferred (J) or P = E= time taken (s) t so t = E P = 2.25 x105 J 3000 W = 75 s