After making 300ml salt solution (sufficient amount of salt in each container until there is undissolved salt at the bottom), divide this solution into three (100ml) parts and place in cup A, Cup B and Cup C. You should have 3 samples A (ice water bath) , B (room temperature water bath) and C (warm water bath) . Let solution stand for 10 minutes at respective temperature bath.
Select three test tubes, label them 1, 2 and 3 and weigh them. Record weight in lab book as wt. test tube (pg. 21)
Measure 1ml of salt solution in warm water bath (glass C) and transfer to the test tubes. Record the temperature of the solution in glass after transferring 1ml of the solution into the test tube. Repeat this step 2 more times until all three test tubes (1,2 and 3 have 1ml
Weigh each test tube with the measured salt solution inside of it. Record the mass of each of the test tube and solution in wt. of test tube + solution column (pg. 21). Repeat for the 2 other test tubes.
Light burner (stove burner if you have a gas stove) and use the test tube holder to grab the test tube and hold it above the flame at an angle. Move the test tube in and out of the flame until all the water evaporates from the test tube leaving a dry white residue.
Alternative method to obtain dry residue shown below, this will take longer time to evaporate the water: Hot plate is being used to evaporate water from all 3 test tubes to obtain salt residue. High heat is avoided (even when using pyrex), test tubes slowly lose water until all three have dry salt residue.
Let test tube with dry salt residue cool and measure weight. Record on page 21 in the wt. of test tube + salt column.
Repeat this for the other 2 temperatures.
Complete the data table and answer follow-up questions.
To calculate wt of solution:
Wt. of solution = Wt of test tube + solution – wt of test tube
To calculate wt of salt:
Wt. of salt = Wt of test tube + salt – wt of test tube
To calculate % salt
% Salt = Wt. of salt X 100
Wt. of solution
Calculate the average of percentages A1, A2, A3, repeat for B1,B2,B3 and C1, C2,C3 . You should have 3 average percentages that correspond with 3 different temperatures.
Plot a graph of average percent (y-axis) versus temperature (x-axis), you should only have 3 points to plot.
Use ruler to draw best-fit line .
Use your plotted graph to determine solubility of NaCl at the desired temperature. Find 40 degrees on your x axis, and draw a dotted vertical line that touches your best fit line. Read the Y value on the graph at the intersection point, this is the % solubility of NaCl you enter for part 17b.
please provide pictures
