5. Oxygen Bomb Calorimeter

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5. OXYGEN BOMB CALORIMETER

(EXPERIMENT NO. 4)

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1. OBJECTIVES:

a) To know the different heats of combustion of

different organic compounds.

b) To know the different parts of a bomb calorimeter.

c) To be familiar with the standard procedure ofoperation of a bomb calorimeter.

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2. THEORY / HYPOTHESIS:

The heats evolved in the complete combustion of many

organic compounds in oxygen have been carefully

determined.

The method ordinarily used is to burn the substance in a

combustion bomb and to measure the heat volume, the

experimentally measured DE 's are converted and

corrected to DH.

The term heat combustion refers to the amount of heat

liberated per mole of substance burned.

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2. THEORY / HYPOTHESIS: (CONT..)

Heats of combustion may be employed directly to

calculate heats of formation of organic compounds.

If the organic compounds contain only carbon,

hydrogen, and oxygen, the supplementary information

required is the heats of formation of carbon dioxide and

liquid water, the usual final oxidation products of such

compounds.

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A bomb calorimeter is an instrument for measuring the

heat of combustion of a substance in which the heat

liberated when the sample is ignited in an atmosphere,

that is of oxygen under pressure, is measured. It is used

to obtain precise thermochemical data.

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The primary equipment used in this experiment is the

bomb calorimeter which is made up of a bomb where

the sample is ignited, the bucket where definite volume

of water is placed and the electronic system which

measures the heat of combustion of the substance

burned.

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3. LIST OF APPARATUS:

Oxygen Bomb Calorimeter

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3. LIST OF APPARATUS:

Oxygen Bomb Calorimeter

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4. SET-UP OF APPARATUS:

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5. PROCEDURE:

1) Pelletized about 0.5 to 1 g of sample using the

pelletizer and place it inside the sample holder.

2) Measure exactly 10 cm of the fuse wire. Lock it in

its place in the bomb electrode forming a loop at its

center and its tip touching the sample.

3) Place the cover of the bomb. Be sure to tighten its

cover.

4) Fill the bomb with oxygen by connecting the

oxygen hose and push the oxygen button.

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5. PROCEDURE: (CONT..)

5) Using the lifting handle, lower the bomb in the

water, push the two ignition lead wires into the terminal

sockets.

6) Lower the bomb completely into water with its feet

spanning the circular boss in the bottom of the bucket.

Carefully check for leak.

7) Press start. Input the sample ID, the bomb number

and weight of the sample.

8) Wait for the first beeping sound and move away

from the calorimeter.

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5. PROCEDURE: (CONT..)

9) At the second beeping sound, record the heat of

combustion and press done.

10) Open the cover and remove the bomb and the

bucket. Remove the knob from the bucket and open the

knurled valve. Knob as the bomb had to release the

residual pressure.

11) After all the pressure has been released, examine

for unburned fuse wire.

12) Straightened the wire and measure its length.

Convert this length calories and subtract this from the

reading obtained.12



6. D ATA AND RESULTS:

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7. SAMPLE COMPUTATION:

8. QUESTIONS:

9. ANSWERS:

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10. DISCUSSION:

11. CONCLUSION / RECOMMENDATION:

12. REFERENCES:

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END

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5. Oxygen Bomb Calorimeter