2.) How much heat must be absorbed at 1357 K to melt a bar of copper (80 * 10 * 12 cm) assume d = 8.93 g/cm^3.
The normal boiling point is 1357 K, and heat of fusion is 13.05 KJ/mol.
Answered below.
heatabsorved= masscopper*Heatfusion
remembering the mass= volume*density.
Watch your units. You will have to change either mass to moles, or heatfusion to kJ/gram.
To calculate the amount of heat required to melt the bar of copper, we need to calculate the mass of the bar and then use the heat of fusion value. Here's how you can do it step by step:
1. Calculate the volume of the bar:
Volume = length * width * height
Volume = 80 cm * 10 cm * 12 cm = 9600 cm^3
2. Convert the volume to mass using the density:
Mass = Volume * density
Mass = 9600 cm^3 * 8.93 g/cm^3 = 85848 g
3. Convert the mass to moles using the molar mass of copper:
Molar mass of copper (Cu) = 63.55 g/mol
Moles = Mass / Molar mass
Moles = 85848 g / 63.55 g/mol ≈ 1351.77 mol
4. Finally, calculate the amount of heat required using the heat of fusion:
Heat required = Moles * Heat of fusion
Heat required = 1351.77 mol * 13.05 kJ/mol = 17635.22 kJ
Therefore, approximately 17635.22 kJ of heat must be absorbed at 1357 K to melt the bar of copper.