Ahmed Mohammed
17-nov-2013
Abstract In this experiment, you will study the effect of changing temperature on the amount of solutet will dissolve in a given amount of water. In this experiment, you will completely dissolve different quantities of potassium nitrate, KNO3, in the same volume of water at a high temperature. As each solution cools, you will monitor temperature using a computer-interfaced Temperature Probe and observe the precise instant that solid crystals start to form. At this moment, the solution is saturated and contains the maximum amount of solute at that temperature.
MATERIALS : computer hot plate
Vernier computer interface stirring rod Logger Pro potassium nitrate, KNO3
Temperature Probe distilled water
2 utility clamps 400 mL beaker four 20* 150 mm-test tubes 10 mL graduated cylinder or pipet test tube rack 250 mL beaker ring stand
PROCEDURE
1. Obtain and wear goggles.
2. Label four test tubes 1-4. Into each of these test tubes, measure out the amounts of solid shown in the second column below (amount per 5 mL). Note: The third column (amount per 100 g of H2O) is proportional to your measured quantity, and is the amount you will enter for your graph in Step 7 below.
Test tube number
Amount of KNO3 used per 5 mL H2O (weigh in Step 2)
Amount of KNO3 used per 100 g H2O (use in Step 10)
1
2
40
2
4
80
3
6
120
3. Add exactly 5.0 mL of distilled water to each test tube (assume 1.0 g/mL for water).
4. Connect the probe to the computer interface. Prepare the computer for data collection by opening the file “12 Temp and Solubility” from the Chemistry with Vernier folder of Logger Pro.
5. Fill a 400 mL beaker three-fourths full of tap