Work Sheet for Heat Capacity

Work Sheet for Measuring HEAT CAPACITY

You will be assigned one substance for which you will determine its relative heat capacity (i.e.: relative to that of water, which is 1.0). The following chart should facilitate your data gathering. After you have made your determination, we will gather the data from all groups and fill in the last column of the chart.

The equation you are using is:

|(Δtemp_water x mass_water)/(Δtemp_x x mass_x)| = C_rel = the SPECIFIC heat capacity of the thing you added

Directions:

Using a level metric measuring cup, put 50 ml of room temperature water into a styrofoam cup. Write its mass in the second empty box after your substance in the chart below.
Using YOUR thermometer, measure the temperature of the water in the cup, and write that value in the empty box at the top lefthand corner of the table below.
With the least amount of handling (perhaps using a perforated plastic ladle), fish out your assigned substance from the icewater bath, bounce it on the towel to eliminate clinging water, and place it in your cup of 50 ml room temperature water. (If you have been assigned ice-water, use 50 ml measuring cup of icewater - but NO ice!)
Swirl for a minute or two so as to attain thermal equilibrium
Measure the temperature of the water, and write that in the empty box at the top righthand of the chart.
Lift out substance and measure its mass on the scale in front of the room, and write that value in the fourth empty box after your substance.
Calculate the temperature change in the water and in the substance, and write those in the remaining empty boxes after your substance.
The multiply the first two values and divide that by the product of the 3rd and 4th values, and place your answer in the fifth empty box. Report your answer to the instructor.

Questions

Which of the substances is the "control"?
Make an additional column, and write in the atomic/molecular/formula weights of the ice-water (18), Al (27), Fe (56) and Pb (207). What correlation exists between those values and your relative heat capacity determinations?
Why would you expect the relative heat capacity of 99°c water to be different from that of ice-water?
Silica glass, SiO₂, has a "formula weight" of 60. Based on your calculations for ice-water, aluminum, iron and lead, what should its relative heat capacity be? Is your experimental determination much too large or too small? Explain the discrepency.
Is your conclusion made in the previous question supported by your determinations for paraffin and plastic?
Since high-polymers (very long ones) undergo chemical reactions (e.g.: enzymes, DNA), is their reactivity mostly due to their huge overall masses? (Finally, we get to a physical basis behind chemistry!)

carbon (coal)
aluminum

T_{water_o}=
numerator denominator T_{water_eq}=

Substance Δtemp_water X mass Δtemp_substance X mass_substance C_rel and notes

ice water
≅ 1.0
*
*

iron
*

lead
*

glass
(quartz = 0.22-0.25)

paraffin wax

plastic

(other)

(other)

* Check your results with those of another class

T_{water_o}=	numerator	denominator		T_{water_eq}=
Substance	Δtemp_water X mass	Δtemp_substance X mass_substance		C_rel and notes
ice water				≅ 1.0
			*
			*
iron				*
lead				*
glass				(quartz = 0.22-0.25)
paraffin wax
plastic
(other)
(other)
* Check your results with those of another class