what is the internal energy chane of 500g of molten lead as it solidifies at its melting temperature? Neglect its small volume change.
To calculate the internal energy change of 500g of molten lead as it solidifies at its melting temperature, we need to consider the phase change from the liquid state to the solid state.
The internal energy change during a phase transition can be calculated using the formula:
ΔQ = mL
Where:
ΔQ is the internal energy change (in Joules)
m is the mass of the substance (in kilograms)
L is the latent heat of fusion (in Joules per kilogram)
The latent heat of fusion (L) is the amount of heat energy required to change one kilogram of a substance from the solid phase to the liquid phase (or vice versa) at its melting point.
For lead, the latent heat of fusion is approximately 24,500 J/kg.
Now let's calculate the internal energy change:
1. Convert the mass from grams to kilograms: 500 g = 0.5 kg.
2. Substitute the values into the formula: ΔQ = 0.5 kg × 24,500 J/kg.
3. Calculate the result: ΔQ = 12,250 J.
Therefore, the internal energy change of 500g of molten lead as it solidifies at its melting temperature, neglecting its small volume change, is 12,250 Joules.