Tip for Problem 4

Both copper (Cu) and silver (Ag) are often cast. Which type of foundry would be more expensive to operate based solely on energy costs? By how much?

	Copper (Cu)	Silver (Ag)
Melting Point	1084^oC	962^oC
Heat of Fusion	2.85x10^10 J/m^3	1.97x10^10 J/m^3
Solid Heat Capacity	3.43x10^6 J/(m^3K)	3.43x10^6 J/(m^3K)
Liquid Heat Capacity	5.48x10^6 J/(m^3K)	2.88x10^6 J/(m^3K)

To help you prepare the answer consider the following.

• Explain what you are calculating? Why?
• Does it make more sense to compare equal masses or equal volumes?
• What is the best way to express the answer as a difference or as a ratio?
• Because the question calls for the answer to be based solely on energy costs, one can ignore the purchase price of the copper and silver.