A 19 kg block of iron at 23 C is rapidly heated by a torch s

A 1.9 kg block of iron at 23 C is rapidly heated by a torch such that 17 kJ is transferred to it. What temperature would the block of iron reach assuming the complete transfer of heat and no loss to the surroundings? If the same amount of heat was quickly transferred to a 890 g pellet of copper at 22 C, what temperature would it reach before losing heat to the surroundings?

Express the final temperatures of the iron and copper in C to two significant figures separated by a comma.

Solution

mass of iron block = 1.9 kg = 1900 g

heat transferred = 17 kJ = 17000 J

specific heat = 0.45 J / goC

Q = m Cp dT

17000 = 1900 x 0.45 x (Tf - 23)

Tf - 23 = 19.88

Tf = 42.88 oC

final temperature = 42.88 oC

b)

mass of pellet = 890 g

temperature = 22 oC

17000 = 890 x 0.385 x (Tf - 22)

Tf = 71.6

final temperature = 71.6 oC