A 2.00-kg block of ice is at STP (0°C, 1 atm) while it melts completely to water. What is its change in entropy? (For ice, Lf = 3.34 ´ 105 J/kg)
To find the change in entropy when the block of ice melts completely, we need to use the formula:
ΔS = q/T
Where ΔS is the change in entropy, q is the heat transferred, and T is the temperature. In this case, we'll also need to account for the latent heat of fusion, Lf.
The heat transferred during the phase change from ice to water can be calculated using the formula:
q = m * Lf
Where q is the heat transferred, m is the mass, and Lf is the latent heat of fusion.
Plugging in the values:
m = 2.00 kg (mass of the ice)
Lf = 3.34 × 10^5 J/kg (latent heat of fusion for ice)
q = 2.00 kg * 3.34 × 10^5 J/kg
q = 6.68 × 10^5 J
Next, we need to find the temperature T at which the phase change occurs. At STP (standard temperature and pressure), the melting point of ice is 0°C or 273.15 K.
Finally, we can calculate the change in entropy:
ΔS = q/T
ΔS = (6.68 × 10^5 J)/(273.15 K)
Calculating this value will give us the change in entropy for the system.