Calorimetry Conservation of thermal energy: Final Temperature: m1 m2 TL Final Temperature:

Calorimetry Example An unknown material of mass .062 kg and temperature 87°C is dropped into .35 kg of water at 20°C. When thermal equilibrium is reached, both have a temperature of 25°C. Calculate the specific heat capacity of the unknown substance.

Calorimetry Problem: A 0.40 kg iron horseshoe that is initially at 500 oC is dropped into a bucket containing 20 kg of water at 22 oC. What is the final equilibrium temperature? Neglect any heat transfer to or from the surroundings.

Calorimetry Problem: A 200 g block of copper at a temperature of 90 oC is dropped into 400 g of water at 27 oC. The water is contained in a 300 g glass container. What is the final temperature of the mixture

Latent Heat Energy is required for a material to change phase, even though its temperature is not changing. (m) Mass of the object (L) Latent heat of the fusion or vaporization (Q) Thermal energy added

Heat of fusion, Lf: heat required to change 1 Heat of fusion, Lf: heat required to change 1.0 kg of material from solid to liquid Heat of vaporization, Lv: heat required to change 1.0 kg of material from liquid to vapor Heat 14 (13 of 32)

Latent Heat Q2= mLf Q4= mLv 3.33 x 105 J 22.6 x 105 J 1 kg Ice -50 oC 50 100 150 Q1= mcIDt 1.05 x 105 J Q3= mcWDt 4.19 x 105 J Q5= mcSDt 1.01 x 105 J Specific Heat Specific Heat Specific Heat

Heat required to convert 1 kg of ice at -50 oC to steam at 150 oC Q1 = 1.05 x 105 J Q2 = 3.33 x 105 J Q3 = 4.19 x 105 J Q4 = 22.6 x 105 J Q5 = 1.01 x 105 J 3.22 x 106 J

Problem: A large block of ice at 0 oC has a hole chipped in it, and 400 g of aluminum pellets at a temperature of 30 oC are poured into the hole. How much of the ice melts?

Problem: 100 W A heating coil is placed in a thermally insulated tank of negligible heat capacity. The tank contains 0.10 kg of water and 0.010 kg of ice, both initially at 0 °C. The coil delivers energy at a rate of 100 W.

Find the heat transferred to the water and ice by the heating coil in the first 10 s.

Find the time required to melt all of the ice

After the ice is melted find the additional time required to bring the water to a boil.