PHYSICAL SCIENCE

EXPERIMENT #6

SOLUTIONS AND SOLUBILITY

 

DATE:________NAME:____________________________SECTION:________ ID#:_____________

 

INTRODUCTION

 

A mixture is a sample of matter composed of two or more substances in varying amounts that are not chemically combined. Mixtures can be homogeneous or heterogeneous. A solution is a homogeneous mixture of two or more substances. The substance in excess in a solution is called the solvent. The substance dissolved is the solute. Solutions in which water is the solvent are called aqueous solutions. A solution in which the solute is present in only a mall amount is called a dilute solution. If the solute is present in a large amount, the solution is concentrated solution. When the maximum amount of solute possible is dissolved in the solvent, the solution is called a saturated solution. The concentration is frequently expressed in terms of the number of grams of solute dissolved in a given quantity of solvent. Example: a solution of salt in water might contain 5 grams of salt for each 100 grams of water.

 

The solubility of a given solute is the amount of solute that will dissolve in a specified volume of solvent (at a given temperature) to produce a saturated solution. The solubility depends on the temperature of the solution. If the temperature increases, the solubility of the solute almost always increases.

 

OBJECTIVE

 

1.                    To determine the concentration of a salt in water solution

 

2.                    To determine the solubility of a substance as a function of temperature.

 

 

APPARATUS

 

 

Salt in water solution of unknown concentration, salt, distilled water, evaporation dish, glass beaker, ring stand with holder to support beaker, thermometer, Bunsen burner, lighter, and beam balance.

 

 

PROCEDURE

 

1.                    The concentration of a solution can be determined by separating the solute from the solvent. Find the weight of each, then calculate the ratio of grams of solute to 100 grams of solvent.

 

(a)                 Weigh a clean, dry, evaporating dish.

 

(b) Obtain from the instructor about 4 cubic centimeters of a salt solution of unknown

concentration. Pour the solution into the evaporating dish.

 

(c)     Weigh the dish plus solution. Record in Data Table 1 (Part 1)

 

(d) Place the evaporating dish on a beaker of gently boiling water and let the water evaporate

from the salt.

 

 

 

(e)     When the water has completely evaporated from the dish, remove the dish from the

Beaker, cool, then remove any moisture from the bottom of the dish. Weigh the dish and residue. Record in the data table.

 

(f)      Determine from your data the weight of the solute and the weight of the solvent in your

Sample.

 

(g)     Determine the concentration as grams of solute per 100 grams of solvent.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Data Table 1

 

Part 1

 

Trial 1 Trail 2

1.                    Weight of clean, dry evaporating dish ________g _________ g

 

2.                    Weight of evaporating dish plus solution .. ________g __________ g

 

3.                    Weight of evaporating dish plus dry residue . ________ g __________ g

 

4.                    Weight of solvent (computed) .. ________ g __________ g

 

5.                    Weight of solute (computed) ________ g __________ g

 

6.                    Grams of solute per 100 grams of solvent (computed) ________ g __________ g

 

Average _________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

QUESTIONS

 

1.                    Define a solution. Give an example.

 

 

 

 

 

2.                    What is a saturated solution?

 

 

 

 

3.                    Distinguish between solvent and solute.

 

 

 

 

 

4.                    Define solubility. Give an example