Purpose: Collect the experimental data necessary to construct a solubility curve for potassium nitrate (KNO3) in water.
Materials: Balance, hot plate, microspatula, 4 boiling tubes (18 x 150-mm), boiling tube holder, boiling tube rack, 400-mL beaker, thermometer, graduated cylinder, stirring rod, iron ring, utility clamp, wire gauze, marking pencil, potassium nitrate (KNO3), distilled water, safety goggles, lab apron
Procedure:
1. Using a marking pencil, the boiling tubes were labeled 1 through 4. They were placed on the boiling tube rack.
2. On a balance, exactly 2.0 g of potassium nitrate (KNO3) were measured out. The salt was poured into boiling tube #1.
3. Step 2 was repeated for the following masses of KNO3 and added to the boiling
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tube indicated: 4.0g to boiling tube #2, 6.0g to boiling tube #3, 8.0g to boiling tube #4 4.
Exactly 5.0-mL of distilled water was added to each boiling tube.
5. A 400-mL beaker was filled about three-fourths full with tap water. This was used a water bath. The beaker was placed on a hot plate and heated to 90C and the temperature was adjusted to maintain the water at about this temperature.
6. The KNO3-water mixture was stirred with a glass stirring rod until the KNO3 was completely dissolved. The stirrer was removed and rinsed. Using the boiling tube holder, the tube was removed.
7. Step 6 was repeated with boiling tube #2 and a warm thermometer (after being placed in the hot water bath) was placed into the solution in boiling tube #1. The boiling tube was held up to the light and the first sign of crystallization was observed As the instant crystallization began, the temperature was observed and
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recorded. 8. Steps 6 and 7 were followed for all four boiling tubes. All temperatures were recorded. Lab Safety: Tie back long hair and secure loose clothing when working with an open flame. Be sure to use a boiling tube holder when removing tubes from the hot water bath. Always wear safety goggles and a lab apron or coat when working in the lab. Results and Data: Boiling Tube # Grams of KNO/ 5.0-mL H2O Crystallization Temperature (C) 1 2.0g/5.0-mL 35 2 4.0g/5.0-mL 51 3 6.0g/5.0-mL 66.1 4 8.0g/5.0-mL 84.5 Calculations: 1.
2.0g/5.0-mL x 20 = 40.g/100-mL
4.0g/5.0-mL x 20 = 80.g/100-mL
6.0g/5.0-mL x 20 = 120g/100-mL
8.0g/5.0-mL x 20 = 160g/100-mL
2. See graph paper for 2 and 3.
Conclusions and Questions:
1. A. 30C: 30g KNO3
B. 60C: 105g KNO3
C. 70C: 130g KNO3
2. Saturated is a term describing a mixture that already contains the maximum amount of solute that will dissolve at that temperature. When a solution can hold more solute than it currently contains, it is called unsaturated. When a solution contains even more that solute than will dissolve, it is supersaturated.
3. A. Supersaturated because that point falls about the solubility curve for KNO3.
B. Unsaturated because that point falls below the solubility curve for KNO3.
4. No, not all ionic compounds fit that description, however the solubility of most ionic compounds increase along with the temperature. When a substance dissolves, it goes from a solid to a liquid, which is an endothermic reaction. When heat is added and the temperature become higher, the extra heat favors the endothermic reaction causing more solid to dissolve rather than crystallize.
5. The solubility of a gas decreases with temperature (e.g., cold water will hold more gas than hot water). For sketch, see back of graph
paper.
Start with the hot water and first measure the temperature. Record it. 8. Then pour 40 ml into the beaker. You can measure how much water was used by looking at the meniscus.
5.) One at a time, place your test tubes in the water bath and heat the first test tube to 25 , the second to 50 , the third to 75, and the last to 100 degrees c. Remeber to stir with your stirring rod every so often.
tablet to completely dissolve in water at different temperatures. Input variables -. Varying surface area of Alka-Seltzer tablet, i.e. if cut into smaller pieces or crushed it will increase the surface area. ( If the surface area is increased (more powdered) the rate of reaction. also increases in the number of people.
Mixed melting point was used to confirm the identity of the product. The smaller the range, the more pure the substance. When the two substances are mixed; the melting point should be the same melting range as the as the melting range obtained after filtering. If the mixed melting point is lower one taken from the crystals, then the two substances are different.
The procedure of the lab on day one was to get a ring stand and clamp, then put the substance in the test tube. Then put the test tube in the clamp and then get a Bunsen burner. After that put the Bunsen burner underneath the test tube to heat it. The procedure of the lab for day two was almost exactly the same, except the substances that were used were different. The
3. Why are the crucible and lid heated at the beginning of the experiment before being weighed?
In this experiment, you will study the effect that several solutes have on the Freezing Point of water. When a solute is dissolved in a liquid, the temperature at which that liquid freezes decreases, because the molecules of the solute become attached to the water molecules, making it more difficult for the water to form its crystaline shape and form into ice. This process is called Freezing Point Depression. In this experiment, you will be determining which of five salts most affects the Freezing Point of water.
I believe that the solubility of the KNO3 will increase at a proportional rate to the increase in the temperature of the water. [IMAGE]When the KNO3 dissolves, it can be classed as a chemical reaction. It follows therefore that in order for the KNO3 to dissolve, an activation energy barrier must be overcome. Activation energy is the energy required to kick-start a chemical reaction. If the activation energy barrier is not reached (i.e. if the particles do not have enough energy on collision to react) then the reaction will not proceed and the KNO3 cannot dissolve in the water.
Potassium is an element on the periodic table that is symbolized by the letter K. The atomic number of this element is 19. At room temperature this element is a solid. Potassium can be found in two forms: either pure or compounds. Pure potassium is described as a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive in water However, Potassium forms many compounds such as Potassium chloride, which is the most common potassium compound (Gagnon, 1). This form of Potassium is especially used in fertilizers as a salt substitute. Another potassium compound is Potassium hydroxide, which is used to make soap, detergents and drain cleaners. Potassium carbonate is used to make some types of glass and soaps. This is also obtained as a byproduct of ammonia. Lastly, Potassium superoxide can create oxygen from water vapor and carbon dioxide. An example of this reaction is “2KO2 + H2O + 2CO2 => 2KHCO3 + O2” (Gagnon, 1). Gagnon also says, “it is used in respiratory equipment and is produced by burning potassium metal in dry air. Potassium nitrate (KNO3), also known as saltpeter or nitre, is used in fertilizers, match heads and pyrotechnics” (Gagnon, 1). Sir Humphrey Davy discovered this element in England in 1807 (Helmenstine, 1). Steve Gagnon, maintainer of the Jefferson Lab website page says, “Sir Humphry Davy first isolated metallic potassium in 1807 through the electrolysis of molten caustic potash (KOH)” (Gagnon, 1). Gagnon also writes, “a few months after discovering potassium, Davy used the same method to isolate sodium. Potassium can be obtained from the minerals sylvite (KCl), carnallite (KCl·MgCl2·6H2O), langbeinite (K2Mg2(SO4)3) and polyhalite (K2Ca2Mg(SO4)4·2H2O). These minerals are often found in ancient...
Measuring cylinder to measure small amounts of fluids. Pipette to gather small amounts of fluids. Test tube holder to hold test tubes. 2. Molar Salt solutions to submerge potato chips in.
Plan 1. Collect 4 different sized beakers 2. Boil some water in the kettle 3. Pour 50ml into each beaker 4. After 1 minute check temperature 5.
2. In the large beaker, put water and boil it completely. After that, remove the beaker from heat. 3. Sample tubes (A-D) should be labeled and capped tightly.
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0.1M HCl, 10 mL of 0.1N KMnO4, 0.2 g. KI, 5 mL of alcohol, and 5 mL of
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