Heat of Formation

Purpose

to verify that heat is released when a new bond is formed

to calculate the amount of heat (cal/g) released when CuSO4 is hydrated by applying the specific heat formula (mass (g) x Δt°C x Cp)

CuSO4(s) + 5H2O(l) CuSO4*5¬¬H2O(s)

Materials

Styrofoam calorimeter and cover

test tube

distilled water

anhydrous CuSO4

dropper pipette

electronic balance (.01g)

scoopula

temperature probe (computer)

graduated cylinder

buret

ruler

beaker

stirring rod

goggles

apron

Procedure

1. Use the buret to measure out 20 mL of H2O into the stryoforam calorimieter

2. Find the mass (g) and the length (mm) of your test tube and record the measurements in the data table.

3. Use scoopula to measure 1 g of anhydrous CuSO4 into the test tube. Record measurement in the data table.

4. Measure the height (mm) of CuSO4 within the test tube, record measurement in the data table.

5. Place the test tube and temperature probe through the holes in the calorimeter cover.

Test-tube spice-rack

Line art representation of a Test tube

Eight cavity test tube mold courtesy of Lake Charl...

Make sure the test tube is touching the bottom of the cup. See Figure 1.

6. Start taking the temperature of the water in the calorimeter using the temperature probe and computer.

7. With a dropper pipette add enough distilled water into the test tube so that the anhydrous salt is covered. Record the number of drops you use.

8. Determine the amount of drops used to cover the cupric sulfate in mL by filling a 10 mL graduated cylinder with the same amount of drops

9. Determine the increase in temperature using the temperature probe and computer and once the temperature has stabilized record the data in the data table.

Data Table

length of test tube 12.5 cm

height of CuSO4¬ in test tube 1.5 cm

mass of test tube 12.11 g

volume of H2O added 4...