How much energy (in J) is lost when a sample of iron with a mass of 27.9 g cools from 78.0 C to 23.0 C ? Express tour answer with the appropriate units. Answer Boxes shows as : Value = Units=

Answer 1

You can use the formula q = mC∆T where...

q = heat = ?

m = mass = 27.9 g

C = specific heat = 0.450 J/g/deg (looked it up)

∆T = change in temperature = 78.0 - 23.0 = 55.0 degrees

Solving for q: q = (27.9 g)(0.450 J/g/deg)(55.0 degrees) = 690.5 J = 691 J (to 3 significant figures)

The sign would be negative (-) since heat was LOST from the iron.

Value = -691

Units = joules