8/23/2019 Determination of Oxygen in Potassium Chlorate

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Mason Keller

Determination of Oxygen in Potassium Chlorate

Purpose: This lab was performed to apply stoichiometry to an actual experimental result and to

determine the concentration of oxygen in potassium chlorate.

Procedure: 

1.  Heat a clean, dry porcelain crucible and cover on a pipestem triangle supported by a ring

stand strongly for 2 minutes. Using clean tongs, transfer the crucible to a clean wire gauze to

cool. When cool, weigh the crucible and cover to the nearest .91g, Record the mass n your

data table.

2.  Transfer approximately 2g of potassium chlorate to the weighed crucible. Determine the

mass of the crucible, contents, and cover to the nearest .01g and record.

3.  Place the crucible on the pipestem triangle, place the cover in position, and heat very gently

for 2 minutes. At 2 minute intervals, gradually increase the temperature until the crucible is

heated strongly. Keep the crucible covered until near the end of the heating, After 10

minutes, remove the burner, take off the crucible cover, and place it on a clean asbestos

square. Heat the crucible strongly, without cover, for 2 or 3 minutes longer. Allow the

crucible to cool, preferable again on a clean wire gauze, and again determine the mass of 

the crucible, contents, and cover to the nearest .01g.

4.  To make sure that all of the oxygen has been removed from the potassium chlorate, the

crucible and cover should be heated again for a about 3 minutes, cooled, and reweighed.

This should be performed repeatedly until the measurements agree within .01g.

Data and Calculations:

KClO3 Crucible,

Original

After 

10min

heating

After 1st

3min

heating

After 2nd

3min

heating

After 3rd

3min

heating

1.99 19.05 20.52 20.5 20.47 20.32

These data were used to calculate the theoretical mass of oxygen and the percentage error.

Theoretical Yield of Oxygen

1.99g KClO3 *

1mol KClO3 *

3mol O*

16g O=

0.78g

O1 122.6g KClO3 1mol KClO3 

1mol

O

8/23/2019 Determination of Oxygen in Potassium Chlorate

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Mason Keller

Percent of Oxygen in KClO3 

.78g* 100 = 0.63% = 0.0063

122.6g

Mass in Grams

OriginalCrucible

and Lid

Original

KClO3 

Final

Crucible,Lid, and

KClO3 

ExperimentalOxygen

Mass

19.05 + 1.99 - 20.32 = 0.72

Percent Error 

Experimental

andTheoretical

Oxygen Mass

(g)

Theoretical

Oxygen

Yield (g)

0.06 / 0.78 * 100 = 7.7%

Conclusion:

The lab went well, excepting the fact that we broke our crucible cover and had to compensate

by measuring in a new lid. However, we did not have enough time to heat to a constant weight. With a

7.7% error, we feel that we were accurate enough for the time we had.