Week 2 - Properties of Mixtures and Fluids Using the Particle Model

3. Pure Substances, Mixtures and Solutions (continued)

Lesson 7: Pure Substances, Mixtures and Solutions (continued)

Textbook Readings

ScienceFocus 8
Pages 24-35
or
Science in Action 8
Page 17-21, 24-29, 34-35

In the previous lesson, you learned that clear ocean water is a solution. One of the dissolved materials in ocean water is salt. You might begin to wonder how much salt can dissolve in water. Does temperature matter? Does everything dissolve in water? These and many more questions will be answered as you examine closely what solutions are all about.

Background Information

As you read your text did you notice that there are many new terms. Be sure to define all of the following terms:

solute	solvent	solubility	concentration	unsaturated solution
agitation	soluble	aqueous	distillation	saturated solution
dissolve	crystallization	evaporation	saturation point	supersaturated solution

Experiment Time:

Read very carefully the descriptions of the factors that affect how quickly a solute dissolves in a solvent. Read the explanations of how the particle model of matter explains this effect.

In this lesson, you are asked to do one type of calculation - that is how to calculate the concentration of a solution in g/mL. An example follows:

You have dissolved 5 grams of sugar in your 250 mL cup of coffee. What is the concentration (in g/mL) of sugar in the coffee?

To solve this type of question, simply divide the mass of the solute by the volume of the solvent.

5 g sugar/ 250 mL coffee = 0.02 g/mL

Thus the concentration of sugar is 0.02 g/mL

Exercise 2.3