Help me study for my Biology class. I’m stuck and don’t understand.
Procedure
- Gather the volumetric flask, distilled water, graduated pipet, pipet bulb, sugar, scale, glass beaker, cup (plastic or drinking), scissors, and a sheet of white paper.
- Tare the digital scale by pressing the Φ/T button so that the scale reads 0.0 g.
- Remove the stopper for the volumetric flask from the top of the flask.
- Place the dry volumetric flask on the scale to determine its mass. Record the mass of the volumetric flask in Data Table 8.
Note: You will use the mass of the dry volumetric flask throughout the experiment.
- Cut a small square of white paper, fold it in half and then in quarters, and place it on the scale.
- Tare the scale by pressing the Φ/T button so that the scale reads 0.0 g with the paper on it. See Figure 16.
- Place 8.0 grams of sugar on the paper. Record the mass in Data Table 8.
- Carefully transfer the sugar from the white paper into the volumetric flask.
- Add approximately 15 mL of distilled water to the volumetric flask containing the 8.0 g of sugar, and swirl the flask until the sugar is completely dissolved in the water.
- Once the sugar is dissolved, use the short stem pipet to add additional water to the 25 mL mark. See Figure 17.
- Record the total volume in Data Table 8.
- Determine the concentration of the sugar solution in the volumetric flask using the following equation:
%m/v=Mass of Sugar (g)Total Volume (mL)×100%
- Record the concentration of the sugar solution in three places: In Data Table 8, for “Concentration,” in Data Table 9 for “Final Concentration” in the “Solution 0” row, and in Data Table 9 under “Initial Concentration” in the “Solution 1” row.
- Tare the scale by pressing the Φ/T button so that the scale reads 0.0 g.
- Place the volumetric flask containing the solution on the scale.
- Subtract the mass of the dry, empty volumetric flask from the mass of the flask containing the solution. The difference is the mass of the sugar solution.
- Record the mass of the sugar solution in Data Table 9 for “Solution 0.”
- Calculate the density of the sugar solution and record it in Data Table 9 for “Solution 0.”
- Pour the sugar solution (Solution 0) into the dry, empty 100 mL glass beaker.
- Rinse the volumetric flask well with distilled water.
- Use the serological (graduated) pipet to transfer 2.5 mL of Solution 0 into the volumetric flask.
- Add approximately 15 mL of distilled water to the volumetric flask containing Solution 0 and swirl to thoroughly mix.
- Using the short stemmed pipet, continue adding distilled water to the 25 mL mark of the flask.
- Tare the scale by pressing the Φ/T button so that the scale reads 0.0 g and then place the volumetric flask containing the solution on the scale.
- Subtract the mass of the dry, empty volumetric flask from the mass of the flask containing the solution.
- Record the mass of the new sugar solution in Data Table 9 for “Solution 1.”
- Calculate the density of the sugar solution and record in Data Table 9 for “Solution 1.”
- Determine the Final Concentration (% m/V) for Solution 1 using the following equation:
C1×V1=C2×V2In this equation:C1=Initial Concentration of Solution 0,V1=Volume Transferred,V2=25 mL,C2=Final Concentration of Solution 1
- Record the Final Concentration of “Solution 1” in Data Table 9 under “Final Concentration.”
- Keep Solution 0 for the remainder of the experiment
- Pour Solution 1 from the volumetric flask down the drain.
- Repeat steps 20-31 for the remaining 3 dilutions using Solution 0 (4.5 mL, 3.0 mL, and 6.0 mL) in Data Table 9.
Note: In step 21, transfer the appropriate volume of sugar solutions (4.5 mL, 3.0 mL, and 6.0 mL). Use the concentration of solution to determine the concentration after dilusion.
- Create a graph displaying the relationship between Concentration and Density for the sugar solution. The x-axis on the chart will be Concentration and the y-axis is Density. Upload an image of the graph into Graph 1.