Activity 2

Factors Affecting Solubility

Glory Grace E. Ortiga

Ivan Mary A. Pascual

De La Salle University-Dasmarinas

Dasmarinas, Cavite Philippines

ABSTRACT

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The activity entitled Factors Affecting Solubility demonstrated how temperature and polarity of solute and solvent affects solubility. A gram of KCl was heated to 40ºC in an ignition tube. The solution was stirred and noted of the take noted of the solubility of KCl. Another gram of KCl was added to the mixture and does the same procedure again. The whole procedure was repeated with NaCl. The solubility of solids in liquids with the effect of temperature shows that the higher the temperature the higher the solubility will be. On the other hand, in determining the effect of polarity of the solute and solvent experiment, it resulted that the highly polarity of the solvent, the higher the miscibility is. In the third procedure, which is the influence of another substance, a pinch of iodine crystal shakes with 10mL water. It was added a pinch of potassium iodide crystals and shake the mixture and it resulted to highly solubility.

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INTRODUCTION

Thesolubility of a solute is the maximum quantity of solute that can dissolve in a certain quantity of solvent or quantity of solution at a specified temperature. The solubility of a solid in a liquid is most affected by temperature, nature of solute particles, and nature of the solvent particles. In general, an increase in temperature increases the solubility of a substance but there are some exceptions to this rule. In order for a solvent to dissolve a solute, the particles of the solvent must be able to separate the particles of the solute and occupy the intervening spaces. Polar solvent molecules can effectively separate the molecules of other polar substances. This happens when the positive end of a solvent molecule approaches the negative end of a solute molecule. A force of attraction then exists between the two molecules. The solute molecule is pulled into solution when the force overcomes the attractive force between the solute molecule and its neighbouring solute molecule. Ethyl alcohol and water are examples of polar substances that readily dissolve in each other.

In the case of gases, an increase in temperature decreases the solubility of gases in liquids while

increased pressure increases their solubility.

Polar solvent dissolve polar solutes to produce solutions, while non-polar solvents dissolve non- polar solutes. The rule of thumb then is “Like dissolves like”. A substance tends to dissolve in a solvent which is chemically related in composition to the substance.

The rate of solution is a measure of how fast a substance dissolves. Some of the factors determining the

rate of solution are size of the particles, stirring, amount of solute already dissolved and temperature.

MATERIALS AND METHODS

A gram of KCl was heated at 400C in an ignition tube. The solution was stirred and take noted of the solubility of KCl. Another gram of KCl was added to the mixture and do the same procedure again. The whole procedure was repeated with NaCl.

A gram or 1mL of the solutes of potassium chloride, coconut oil, toluene, copper sulfate was determined

the solubility in 1mL water, 1mL isopropyl alcohol and 1ml (1:1V/V water: isopropyl alcohol.