Sample Heat Transfer Problem:

How many joules of heat are needed to raise the temperature of a 50 g piece of copper metal from 5 ^oC to 30 ^oC?

Problem Solution:

• Use the equation q = m(ΔT)C_p
• If the specific heat is not given in the problem, it must be looked up.
• Add numbers to the equation: q = 50 g Cu (30 ^oC − 5 ^oC) 0.385 j/g • C^o
• Notice that the units of specific heat are such that everything except heat units cancel in the equation!
• Solve for ΔT: 30 ^oC − 5 ^oC = 25 C^o (ΔT is always positive)
• Solve the equation: q = (50 g) (25 C^o) (0.385 j/g • C^o) = 481 joules

Heat Calculations