Heat Energy
CH 6A - Chapter 4
Instructor: J.T.
A 500.0 g piece of iron is heated in a flame and dropped into 400.0 g of water at 10 degree C C. The
temperature of the water rises to 90.0 C. How hot was the iron when it was removed from the flame?
(The specific heat of iron is 0.473 J/ g C)
Heat lost by iron = Heat gained by water
q(iron) = q(water)
q = m. c. ∆t
X = initial temperature of iron.
𝑱
We know: The specific heat of water is : (𝟒. 𝟏𝟖𝟒 𝒈 ℃)
(𝟓𝟎𝟎. 𝟎 𝒈) (𝟎. 𝟒𝟕𝟑
(𝟐𝟑𝟕
𝑱
℃
𝑱
𝑱
) (𝒙 − 𝟗𝟎. 𝟎℃) = (𝟒𝟎𝟎. 𝟎 𝒈) (𝟒. 𝟏𝟖𝟒 𝒈 ℃) (𝟗𝟎. 𝟎℃ − 𝟏𝟎. 𝟎 ℃)
𝒈℃
) 𝒙 − 𝟐. 𝟏𝟑 × 𝟏𝟎𝟒 𝑱 = 𝟏. 𝟑𝟒 × 𝟏𝟎𝟓 𝑱
(𝟐𝟑𝟕
𝒙=
𝑱
) 𝒙 = 𝟏. 𝟓𝟓 × 𝟏𝟎𝟓 𝑱
℃
𝟏. 𝟓𝟓 × 𝟏𝟎𝟓 𝑱 ℃
= 𝟔𝟓𝟒 ℃
𝟐𝟑𝟕 𝑱
A 20.0 g piece of metal at 203 C is dropped into 100 water at 25.0 C . The water temperature rose
to 29.0 C. Calculate the specific heat of metal (J/g C). Assume that all of the heat lost by the metal
is transferred to the water and no heat is lost to the surroundings.
q(metal) = q(water)
q = m. c. ∆t
X = the specific heat of metal.
𝑱
We know: The specific heat of water is : (𝟒. 𝟏𝟖𝟒 𝒈 ℃)
(20.0 𝑔)(𝑥)(203. ℃) = (100.0 𝑔) (4.184
𝐽
) (29.0℃ − 25.0℃)
𝑔℃
(3480 𝑔℃)𝑥 = 1674 𝐽
𝑥=
1674 𝐽
𝐽
= 0.48
3480 𝑔℃
𝑔℃