Solutions Lab

SC IS 3.2.1 LAB

3.2.1. Solutions Lab

Background:

A solution is a homogeneous mixture of one or more solutes dissolved in a solvent.

* solvent: the substance in which a solute dissolves to produce a homogeneous mixture.

* solute: the substance that dissolves in a solvent to produce a homogeneous mixture.

Note that the solvent is the substance that is present in the greatest amount.

Water is considered the universal solvent.

The amount of solute that can be dissolved in a definite amount of solvent is used as the measure of solubility. The conventional reference for solubility is the number of grams of solute that can dissolve in 100 mL of solvent.

A solution that has reached its maximum solubility is called a saturated solution. A solution may, however, become supersaturated, due to what can be attributed to a kinetic factor. Temperature and pressure may contribute to the kinetic factor; therefore, they also affect the solubility of a solute.

Electrolytes or ionic substances are soluble in water due to hydration. Due to the strong polarity of the water molecule, the positive and negative ions are pushed apart. In general, reasonable-sized ions are believed to have six water molecules around them, but these water molecules readily exchange with those in the medium.

Purpose:

* To determine if the amount of solute that can be dissolved in water will increase with an increase in temperature.

* To compare two different solutes and observe if their solubility is affected differently by differing temperatures.

Materials:

* Salt

* Sugar

* Measuring Spoons

* Measuring Cups

* Clear Cup

* Thermometer

* Water

* Spoon

* Ice

Procedure:

Part I

1. Make a hypothesis as to what you believe will happen.

2. Make 6 ounces water cold - add ice cubes - take the temperature and record. The temperature of the water should be approximately 1 or 2 deg C (34-35.5 deg F).

3. Add a teaspoon of salt and mix - continue mixing until it is dissolved -- once it has dissolved, add Ð... a teaspoon of salt and continue mixing until dissolved. Continue this process until no more salt will dissolve. Record the total amount of salt added.

4. Make 6 ounces of water room temperature -- take temperature and record. The temperature of the water should be approximately 25 deg C (77 deg F).

5. Add a teaspoon of salt and mix. Continue mixing