Investigating the Standard Enthalpy of Potassium Nitrate
Stability
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Stable. Strong oxidizer - contact with combustible material may cause
fire. Incompatible with combustible materials, and strong reducing
agents.
Toxicology
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Harmful if swallowed. May cause reproductive disorders.
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Hazard: oxidizing
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Aim
The aim of this experiment is to determine the crystallisation
temperature of the solution potassium nitrate at different
concentrations and use information to find out the standard enthalpy
of potassium nitrate.
Equipment and reagents
· Boiling tubes
· Dark card
· Bunsen burner
· Thermometer
· Weighing scale
· Burette (50cm3)
· Clamp
· Stand
· Potassium nitrate
· Deionised water/ distilled water
Safety
· Wear goggles for eye protection at all times.
· Laboratory coats must be worn at all times.
· Wear gloves to avoid chemical contact to skin, potassium nitrate.
· Long hair was tied back when Bunsen burners were used.
Procedure
1. 10g of potassium nitrate were weighed out and placed into a
boiling tube, and then the exact mass was noted in a result table.
2. Exactly 8.0cm3 of deionised water was added to the boiling tube
containing the potassium nitrate. This was done by using a
burette.
3. The tube was then heated gently until the crystals were dissolved
and then the heat source was removed.
4. The tubes were allowed to cool for safety reasons. The
temperature at which the crystals were first appeared was noted. A
dark card was used for this purpose. The results were recorded.
5. A further 25cm3 of distilled water was added and steps 3-4 were
repeated.
6. A further 25cm3 of distilled water was added and steps 3-4 were
Each subsequent trial will use one gram more. 2.Put baking soda into reaction vessel. 3.Measure 40 mL vinegar. 4.Completely fill 1000 mL graduated cylinder with water.
The theoretical weight was 599.6 mg. This yields a percent yield of 3.7%. Table 1 also illustrates the experimental melting point of 99.3-102.1◦C. A melting point that has a range larger than 3◦C is indicative of impurities in the sample. A few possibilities of impurities could have been unreacted norbornene, and water. Evidence that supports that there was unreacted norbornene in the final sample was the fact that the product was a jelly-like structure. Norbornene by itself has a jelly-like structure. However, once norbornene reacted with the acid-catalyst (H2O2), then it should have changed the chemical structure of the molecule and once the solution was brought back down to room temperature, crystals should have formed. Since a jelly-like, or oil-like product was present at the end of the reaction, then this is indicative that there was unreacted norbornene in the sample. The second impurity that may have been present in the final product was water. Instead of adding 3 mL of sodium bicarbonate and then 3 mL of brine, 3 mL of brine was added first and then 3 mL of sodium bicarbonate was added. This experimental error caused excess aqueous solution to be added to the diethyl ether. Since excess water was added to the final product, about 4x the amount of anhydrous sodium sulfate was needed in order to remove the water from the product. This was another indication that there was too much water in
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In this report, we will be analyzing the current performance of Kingsford in the marketplace and identify the main cause of revenue deterioration. Thereafter, a comprehensive strategy and marketing plan will be presented.
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7.The covered crucible was placed over the flame of the Bunsen Burner using a ring stand.
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