WHAT ARE THE FACTORS THAT

AFFECT THE SOLUBILITY OF

SDSA PRESENTATION BY: LYNDSEY, JORDY AND JEN

RESEARCH QUESTIONS

1. How does the polarity of the solvent affect the solubility of the solute?

2. How does the temperature of the solvent affect the solubility of the solute?

VARIABLES

Dependent Variables

Degree of solubility

Independent Variables

Temperature

Polarity of Solvent

Controlled Variables

Mass of Solute

Volume of Solvent

Sample Solute

Time

SODIUM DODECYL SULFATE (SDS)

Non-Polar Polar

• Anionic surfactant• Amphiphilic• Lowers the surface tension of aqueous

solutions• Used primarily in: soaps and detergents

THE SOLVENTS

1. Water

• Strongly Polar Solution

2. Isopropyl Alcohol

• Polar Solution

3. Vegetable Oil

• Non-Polar Solution

WHAT IS “SOLUBLE”?

• Dissociation of salt

• Lack of visible crystals

• 1g dissolves in 100mL

METHOD

• 100mL of solvent (water, isopropyl alcohol or vegetable oil) was measured into a 400 mL beaker that contained a stir bar

• The solvent was cooled/heated to the desired temperature

• 1 g of SDS was added to the beaker

• The solution was allowed to stir for 30s

• After 30s the solution was examined to determine if there was a homogeneous mixture

RESULTS

Temperature 4°C RT 40°C 70°C

Water Insoluble Soluble Soluble Soluble

Vegetable Oil Insoluble Insoluble Insoluble Insoluble

Isopropanol Soluble Soluble Soluble Soluble

OBSERVATIONS: WATER

Temperature: 4°CInsoluble

Room TemperatureSoluble

OBSERVATIONS: WATER

Temperature: 40°CSoluble

Temperature: 70°CSoluble

OBSERVATIONS: ISOPROPYL ALCOHOL

Temperature: 4°CSoluble

Room TemperatureSoluble

OBSERVATIONS: ISOPROPYL ALCOHOL

Temperature: 40°CSoluble

Temperature: 70°CSoluble

OBSERVATIONS: VEGETABLE OIL

Temperature: 4°CInsoluble

Room TemperatureInsoluble

OBSERVATIONS: VEGETABLE OIL

Temperature: 40°CInsoluble

Temperature: 70°CInsoluble

ANALYSIS: COMMON TRENDS

• The solubility of SDS in a nonpolar solution was independent of the temperature of the solution

• No clear trends were visible for polar solutions due to insufficient data

• SDS is mostly soluble in polar solutions

• SDS is insoluble in nonpolar solutions

SOURCES OF ERROR

• Errors associated with measurement

• Inconsistent room temperature

• Inconsistent stirring speed

• Production of bubbles from surfactant

• Influences the solubility determination

IMPROVEMENTS

• Require: Quantitative Analysis

• Determine the maximum concentration of the solute able to dissolve in the solvent at the given temperature

• Better regulation of temperature

• Purity of Solvent

• Investigation of Common Ion Effect by way of different solvents

CONCLUSION

• SDS is soluble in polar solutions at a variety of temperatures

• SDS is insoluble in nonpolar solutions

• The structural properties of isopropyl alcohol contain polar and nonpolar ends allowing it to associate with the amphiphilic properties of SDS resulting in a lack of bubbles