T540: Prep Notes

Introduction

Equal masses of aluminum and lead are heated in boiling water.  The metals are then placed in separate beakers containing equal volumes of room temperature water.  The temperature change in each amount of water is measured and specific heats can be determined.

Equations 

Using the mass of the metal, the mass of water in the cooling beaker, and the change in temperature of the water, the specific heat capacity for the metal can be found.

qH2O = mH2O . cH2O . ΔTH2O

qmetal = -qH2O

cmetal = qmetal/(mmetal . ΔTmetal)

The ΔTmetal is Tf-Ti, where Tf is the final temperature and Ti is the initial.  The initial temperature is that measured in the boiling water.  The final temperature of the metal is that measured in the cooling beaker.

Supplies

1.         Prepare the following chemicals:

    • Prepare equal masses (~100g each) of lead and aluminum.  Weigh and include mass with demo.

2.         Assemble the following equipment:

    • 800mL beaker filled with 300 mL water for boiling (sufficient amount to cover metals).
    • 800mL beaker with room-temperature water
    • large graduated cylinder to measure water volumes
    • two styrofoam cups (nested in 400mL beakers for stability) with room-temperature water (fill from same source)
    • three thermometers (digital or mercury-filled)
    • hot plate
    • heat protected gloves
    • tongs
    • sieve and container to collect water 

To Conduct Demonstration

    1. Bring an 800mL beaker of water to boiling.
    2. Place equal masses of lead and aluminum in the boiling water and allow them to heat for several minutes.  Measure the temperature of the water.
    3. Remove the metals and place them in separate beakers containing the same volume of room-temperature water.
    4. Stir water and measure the maximum temperature reached in each beaker.

 Demo Time: 10 – 15  minutes

Safety and Disposal

Use tongs and/or heat-protective gloves to remove hot metals.