The purpose of this experiment is to find the solubility of salt in water at various temperatures.
Key results from this experiment are the temperatures at which the crystals start forming, letting us know that the salt has dissolved, and therefore telling us the solubility of the salt. We know, from comparing our results to the expected results, that we made a few major errors in our calculations involving the temperature at which the crystals started to form.
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Regardless, we concluded that the solubility of salt is not a stable figure, but varies depending on the amount of water, he amount of salt added, and the temperature of the water. The purpose of this lab is to determine the solubility of how much a salt can dissolve in water, of KC103 (potassium chlorate). In particular this lab will be determining the solubility at different temperatures.
The water molecules are arranged in a hexagonal shape. All of the oxygen atoms have a negative charge, point towards the hydrogen atoms of other water molecules, having a positive charge.
When the KCI hits the water, the K+ and Cl- ions dissociate. These ions will now be attracted to the appropriate opposite charges on the water and “fit in” between the water molecules ith the charges all aligned, causing the potassium chlorate to dissolve. Materials and Methods Large test tube and clamp 10-mL graduated cylinder Ring stand Tap water 110 oc thermometer Bunsen burner 4.
5-5. 0 g potassium chlorate Experimental Procedure Assemble the apparatus.
A 20 cm test tube is used with the thermometer as your apparatus then attached to a ring stand with a clamp. 4. 5-5 grams of salt was weighed on a balance, then the exact mass was recorded on a data sheet. A graduated cylinder was then used to measure out 10 mL of water, and then added to the salt in the apparatus.
The mass of the water added was recorded to the data sheet. The apparatus was then clamped to the ring stand, and heated. While being heated, the water in the test tube was being stirred continuously until crystals of salt were forming.
The exact temperature of the water was then recorded when the crystals tormed . The test tube was then cooled down until it was warm to the touch. Then about 4 mL of water is measured and added to the previous 10 mL in the test tube.
The experiment is then repeated 4 more times, adding 4 more mL of water to the test tube each time and recording the temperature of the water as crystals begin o form. Results. On the first session, with only 10 mL of water in the test tube the salt began crystallizing at 900C.
After adding 4 mL to the previous 10 mL of water in the test tube, the salt began crystallizing at 900C. With 18 mL of water in the test tube, the salt began crystallizing at 850C. With 22 mL of water in the test tube, the salt began crystallizing at 950C.
With 26 mL of water in the test tube, the salt began crystallizing at 890C. The general equation we used to find the salt concentration is the mass of salt/mass of water = x/100g water. For the first session, the equation would look like his; which x would equal 45gKC103/100g H20.
This process was repeated 4 more times to calculate the salt concentration for each session. Discussion. As you can see by the initial results, we were nowhere close to the expected results.
Part of the reason for this is we did not control the temperature of the test tube; rather let it sit and heat up until crystals formed. Another reason for faulty results is our group did not stir and watch the test tube as closely as we should have, allowing crystals to form and the test tube to rapidly heat up before we record the data.