7.5 pts Question 4 The electrical components of a refrigeration unit malfunction
ID: 587683 • Letter: 7
Question
7.5 pts Question 4 The electrical components of a refrigeration unit malfunctioned, releasing 70kJ of energy (assume all of this energy enters the ice system). If the unit contained 100.0 g of ice held at -10° C, what will the final temperature be (in Celsius, rounded to the nearest whole digit)? Boiling point Melting point Enthalpy of vaporization Enthalpy of fusion Specific heat capacity (solid) 2.11 J(g K) Specific heat capacity (liquid) 4.18 J/(g K) Specific heat capacity (gas) 2.08 J/g·K) 373 K 273 K 2,260 J/g 334 J/gExplanation / Answer
Energy required to change the temperature of ice from - 10°C to 0°C
Q1 = m x Cp x (T2-T1)
= 100 g x 2.11 J/g-K x 10 K
= 2110 J = 2.11 kJ
ICE convert to water
Q2 = m x enthalpy of fusion
= 100 g x 334 J/g
= 33400 J = 33.4 kJ
Total energy released = Q1 + Q2 + Q3
Q3 = 70 - 2.11 - 33.4 = 34.49 kJ
Q3 is the energy required to reach the temperature of Water from 0°C to T °C
Q3 = m x Cp x (T-0)
34.49 * 1000 J = 100 g x 4.18 J/g-K x ( T )K
T = 82.5 °C