science teacher's guide - DepEd Naga City

Activity3What is the Evidence that a Solution is Saturated?Teacher's GuideModule 1: SolutionsAnswers to QuestionsQ1. The solution appears uniform throughout. It is homogeneous.Q2. Five and ½ teaspoons of sugar were added when there was excessundissolved sugar observed remaining in the container.Q3. Five teaspoons of sugar is the maximum amount that can dissolvein 20 mL of water.Note:Activity 3 is done at room temperature only. The effect of temperatureon solubility is not yet discussed in Grade 7. Activities 4 to 6 will deal onlywith the factors affecting how fast a solid solute dissolves in water.While in general, solubility of solute increases as temperature isincreased, it should be noted that the relationship between temperature andsolubility is not simple. Faster dissolving does not necessarily mean moreextensive dissolving. It is important to distinguish the effect of temperatureon how fast the process of dissolving takes place from its effect on the finalamount of solute that will completely dissolve.The solubility of some solutes decreases as temperature increases.On the other hand, there are solutes that increase their solubility at highertemperatures. For some other solutes, their solubility is not affected by anincrease in temperature. Since the effect of temperature on different solutesis more accurately explained using solubility curves, Grade 7 students arenot expected to use these solubility curves, which will be taken up in Grade9. The effect of temperature on the solubility of gases in liquids will also betaken up also in Grade 9.Teacher Demonstration: Concentration of SolutionsMaterialsWHAT ARE THE PROPERTIES OF SOLUTIONS?food color (blue, yellow, or green)medicine dropperswater4 clear, transparent bottlesstirrerGrade 7 Science: MatterDiversity of Materials in the Environment 4