PRE-LAB DISCUSSION:The amount of heat required to raise the temperature of a solid body depends on its change in temperature (ΔT), its mass (m), and an intrinsic characteristic of the material forming the body called specific heat (cp)

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PRE-LAB DISCUSSION:The amount of heat required to raise the temperature of a solid body depends on its change in temperature (ΔT), its mass (m), and an intrinsic characteristic of the material forming the body called specific heat (c_p). The heat is calculated from the equation

Q = c_p x m x ΔT

The unit for c_p is thus heat per unit mass per unit temperature. The value of c_p does depend on the temperature. However, for the small temperature range we are interested in, it is a good approximation to regard c_p as temperature independent. Historically, heat (q) was measured in terms of calories. The calorie was defined as the amount of heat required to raise the temperature of 1 gram of water by 1 ºC from 14.5 ºC to 15.5 ºC at 1 atmosphere pressure. With this definition, the specific heat of water is 1.00 cal/(g · ºC). The use of the calorie began before it was established that heat is a form of energy and 1 calorie is equivalent to 4.18 J. The joule (J) has become the more favored unit in recent years. Thus, the units for c_p that we will use are J/(g · ºC). The specific heat of water is then 4.18 J/(g · ºC).

PURPOSE:The purpose of this lab is to apply the experimental methods of calorimetry in the determination of the specific heat of several metals.

1. PROCEDURE:Follow the guidelines for lab write-ups. Your lab must be submitted handwritten or typed. It cannot be a printed version of this page. It will be graded according to the standards in the Lab Rubric.
2. Use the Flash lab animation to observe the relationship between specific heat and temperature change for the known metals (Silver, gold, copper and iron).
3. Perform three trials for EACH of the two unknown metals (X and &). Record the mass of the sample, the initial temperature (T₁), the final temperature (T₂), and the energy absorbed (in joules).
4. Vary the mass of the sample and the initial temperature of the water and metal for each trial with a given material. In other words, no two trials for a given material should use both the same masses and the same initial temperatures.
5. At the end of each trial, hit the "Reset" button to prepare for the next trial.
6. Because no specific heat values are given for Metal X and Metal Y, you will be expected to use the experimental data to find the specific heat of each.

 

Flash simulation produced by Iowa State University

 

 

Results

OBSERVATIONS AND DATA:Metal____________Trial #1Trial #2Trial #3Mass of metal, m (g)gggInitial temperature of metal (T₁)ºCºCºCMass of water, m (g)gggInitial temperature of water (T₁)ºCºCºCFinal temperature of the system (T₂)ºCºCºC

 

CALCULATIONS: Show your work! You will repeat the calculations three times for both metals you test.

1. Calculate the value for Q_water, using the known values of m_water, ΔT_water and the specific heat of water, 4.18 J/(g·°C). Remember that ΔT = (T₂ - T₁). Do this for each trial, recording your results in the table. Be sure to show your calculations.
2. Recognize that the heat absorbed by the water was the heat lost by the metal. Change the sign on Q to a negative, and use that as Q_metal. Then...
3. Calculate the specific heat of the metal, C_p. C_p = Q_metal ÷ m_metal ÷ ΔT_metal. Be sure to show your work, and your results in the table below.

Material____________Trial #1Trial #2Trial #3Q_water      ºC      ºC      ºCC_p for the metal      J/(g · ºC)      J/(g · ºC)      J/(g · ºC)