I. Which Solute Is More Soluable?
II. Introduction:
Question:
Which two substances (sodium chloride and sodium nitrate) have the most solubility?
Hypothesis:
If we dissolve the two substances separately in water, then the sodium chloride will dissolve more because the ions in the solid is so strong that only highly polar solvents like water dissolve the sodium chloride well (NaCl).
Background Information:
Solubility: the rate at which a solute dissolves in a solvent.
Saturated: contains as much as can be dissolved in the solvent.
Solute: substances that are dissolved in the solvent.
Solvent: heterogeneous mixture in which particles are dispersed through a fluid but not dissolved in it.
NaCl: (Sodium Chloride)
Represents 1:1 ratio of sodium and chloride
The attraction between the NA+ and the Cl- ions in the solid is so strong that only highly polar solvents like water dissolve NaCl well.
When dissolved in water, the sodium chloride framework disintegrates as the Na+ and Cl- ions become surrounded by the polar water molecules. The chloride ions are strongly solvated, each being surrounded by an average of 6 molecules of water.
NaNo3: (Sodium Nitrate)
White solid, very soluable in water
Sodium nitrate is also synthesized industrially by neutralizing nitric acid with sodium carbonate or sodium bicarbonate
Sodium nitrate was used extensively as a fertilizer and a raw material for the manufacture of gunpowder in the late 19th century.
****(Information for Sodium Chloride and Sodium Nitrate came from Wikipedia)
III. Materials/Illustration:
Test Tubes (2-4)
Rubber Stoppers (2-4)
10 ml H2O (cold tap water)
Graduated Cylinder
Sodium Chloride (NaCl)
Sodium Nitrate (NaNo3)
Test Tube Holder/Rack
Scale (Electronic Balance)
Scoops
Pipette (optional)
IV. Variables
Independent (manipulated)
The substances: Sodium Chloride (NaCl) and Sodium Nitrate (NaNo3)
Dependent (responding)
Grams of Solute
Constant (control)
Amount of H2O (water), Amount of shakes (80 shakes)
V. Procedures:
1. Gather materials (from the materials list)
2. Set up lab on a flat surface as shown in the diagram/illustration.
3. Use the scale (electronic balance; already tared) to weight the container of the Sodium Chloride (NaCl).
4. Record the mass of the container into your data table under “Initial Mass” for Sodium Chloride.
5. Fill the graduated cylinder with exactly 10 ml. of cold tap water from the sink. After, record the volume into your data table under “Volume”.
6. Pour the contents (10ml. cold tap water) from the graduated cylinder into one of the test tubes.
7. Using the scoop/scooper, place 2-3 scoops of the Sodium Chloride into the test tube.
8. Use the rubber stopper to cover the top of the test tube.
9. Holding your thumb or finger over the rubber stopper, shake the test tube 80 times.
10. Check the test tube to see if the Sodium Chloride has dissolved by holding the test tube horizontally and rolling it to see if there are any particles left.
11. Repeat steps #7 - #10 until the substance inside the test tube becomes saturated. Meaning, that it contains as much Sodium Chloride as can be dissolved in water. (the Sodium Chloride can no longer be dissolved in the solvent and small particles/grains start to show)
12. Once your substance is saturated, take the container of your Sodium Chloride and place it on the scale (electronic balance; already tared).
13. Record the mass of the container into your data table under “Final Mass”.
14. Repeat steps #3 - #13 for 2 more trials.
15. Once you are done with all three trials for the Sodium Chloride, Repeat steps #3 – 13 for Sodium Nitrate.
VI. Observations and Data:
Sodium Chloride (NaCl)
Trials
