Science 14 Unit A: Investigating Properties of Matter Chapter 3 Mixtures and Their Uses pp. 40-57 WORKBOOK Name:
3.1 Two Kinds of Mixtures pp. 42-44 Read pp. 42-43 Mixtures are represented on the right side of the classification of matter flowchart See Figure 3.1 p. 42 Mechanical Mixtures two or more types of particles visible (observable components) o Example: orange juice with pulp, concrete, chocolate chip cookie, etc. Solutions two or more substances are combined and you can NOT see the difference between them (uniform mixture) appear to have only one type of particle that looks the same throughout o Example: iced tea, syrup, pop, shampoo Parts of a Solution: 1) Solute substance that dissolves. There is less of this in the solution. Example: hot chocolate crystals 2) Solvent substance in which the solute dissolves. There is more of this in the solution. The universal solvent is water because almost everything will dissolve in it. Solute (less) dissolved in Solvent (more) o solute + solvent = solution See Figure 3.4 p. 42 Determining if a substance is a mechanical mixture or a solution: 1) Visually see one or more types of particles, i.e. sand and marbles mixed observable components, therefore a mechanical mixture 2) Pour the mixture through a filter. If a substance collects in the filter, then it is a mechanical mixture. If nothing is collected in the filter, then the mixture is a solution. 3) Use distillation to confirm that a solution is not a pure substance 1
Classification of Matter Practice Matter can by classified as a pure substances or a mixture. Classify each of the following substances as an element (E), compound (C), solution (S), or mechanical mixture (M). 1) sand 1) fresh air 2) salt 2) carbon dioxide (CO 2 ) 3) pure water (H 2 O) 3) gold 4) soil 4) salt water 5) soda 5) salad dressing 6) bronze 6) oxygen 7) chocolate milk 7) silver 8) hydrogen peroxide (H 2 O 2 ) 8) apple pie 9) iced tea 9) potassium 10) soda 10) calcium carbonate (CaCO 3 ) 11) Kool-Aid 11) sugar water 12) coffee with milk 12) cup of tea, with floating tea leaves 13) baking soda (NaHCO 3 ) 13) chocolate chip cookie Discuss CYU p. 44 #1-3 2
Read p. 45 3.2 What are Solubility and Concentration? pp. 45-50 Concentration describes the amount of solute in a solution [ x ] means concentration of substance x usually show the amount of grams of solute in one liter of solvent (g/l) o Example: Round-up is a herbicide, glyphosate, that is diluted with water. [glyphosate] = 7.0g/L There is 7.0 g of glyphosate in 1L of product. The rest is water. can also show as percent weight per volume (% W/V) o Example: household hydrogen peroxide has a concentration of 3% W/V There is 3g of peroxide in 100mL of product. The rest is water. C = quantity of solute quantity of solution saturated maximum [solute] in solution at specified conditions Read p. 46 Solubility describes how easily a solute will dissolve in a solvent to make a solution. Example: rocks have a very low solubility (difficult to detect dissolving) whereas sugar has a high solubility and dissolves almost instantly When a solute does dissolve we say it is soluble in that solvent. o Example: sugar and salt are very soluble in water If the solute does not dissolve, it is insoluble in that solvent. o Example: oil and gasoline are insoluble in water. i.e. water and oil are immiscible See Figure 3.6 p. 46 Discuss Lava Lamp Demonstration Increase Solubility: 1) add heat ( T solubility) 2) agitate (stir) 3) break solute into smaller pieces (increase surface area) 4) apply pressure (compress solution increase solubility) 3
How Does Temperature Affect Solubility? Investigation 3-A p. 47 Think About it Based on the particle theory, what happens to the particles of a substance as it is heated? Do you think heating a solution will increase the amount of solute that will dissolve? In this investigation you will examine data showing various substances ability to dissolve in water at different temperatures as well as develop a theory about how temperature affects solubility. What to Do Follow the instructions listed on page 47 in the textbook. There is space on the next page of your workbook to construct a graph. Analysis Please record your answers below or on an attached sheet of loose leaf. 1. Are the graphed lines straight or curved? 2. Examine the lines of the graph. As temperature increases, what happens to the lines? 3. Extrapolate the data on the graph to predict the solubility of each solute at 95 C. 4. Which solute has the highest solubility at each of the following temperatures? a) 20 C b) 60 C c) 95 C 5. What happens to the solubility of a solute as the temperature of a solution increases? 4
How Does Temperature Affect Solubility? Continued 5
Read p. 49 How Soap Works grease is not soluble in water, however, it is soluble in a soap solution soap has the ability to dissolve in water or oil to form a solution soap can dissolve grease or other oil stain so that when it is rinsed, the stain gets washed away with the water. See Figure 3.7 p. 49 Discuss CYU p. 50 #1-5 6
Solubility of a Gas BLM 3-4 Carbon dioxide escapes from your pop as it warms, making it go flat. Ice water contains more oxygen than warm water. Bubbles form on the inside of a glass of water as it sits on the counter. How are these facts related to solubility? As you know, particles in a substance move faster when they heat up. You also know that the particles in a gas move very quickly. As a solution heats up, its particles move more and more quickly. Eventually, the particles of the gas are moving so quickly that they can escape their bonds with the liquid. Purpose Examine the graphs provided and answer the questions in the space provided. 7
Solubility of a Gas BLM 3-4 Continued Analysis 1. Examine the solubility of carbon dioxide graph. a) What is its solubility at refrigerator temperature (about 6 C)? b) What is its solubility at room temperature (about 25 C)? c) Does the solubility of carbon dioxide change more from 20 50 C or from 50 80 C? 2. Examine the solubility of oxygen graph. a) The freezing point of water is 0 C. What is the solubility of oxygen at that temperature? b) What is the maximum concentration of oxygen in fish tank water at about 24 C? c) Which will contain more oxygen, boiling water or an ice cube? Explain. 3. Which is more soluble at 20 C, oxygen or carbon dioxide? 4. How can you prevent pop from going flat? 5. Whipped cream is a frothy mixture of air in cream. As the mixture heats up, what will happen to the air in it? Will the cream stay whipped? Explain. 6. Write a hypothesis about the relationship between temperature and the solubility of a gas. 8
3.3 Separating Mixtures pp. 50-55 Read p. 50 Read Did You Know and Off the Wall p. 50 Dirty water is a mechanical mixture and the pure water needs to be separated from the impurities before it is drinkable. Read p. 52 Crystallization separation process where the solvent is evaporated, leaving crystal solute behind to be collected o Example: salt left when evaporate ocean water Read p. 54-55 Purifying Water Water Treatment Plant Process: See Figure 3.9 p. 54 1) Add alum (coagulant chemical) to impure water which surrounds bacteria, viruses and dirt particles, making the alum very heavy. 2) The heavy alum sinks to the bottom and the clearer i. water is then easily separated. 3) Charcoal filters to remove any remaining dissolved i. impurities. 4) Add chlorine to water to kill any remaining bacteria. Distillation process where a solution is boiled and the vapor from it is collected separates solution into solute and solvent when steam (water vapor) cools and condenses it forms pure drinkable water. o Anything that was dissolved in the water (i.e. salts, minerals, bacteria, viruses, etc.) will remain behind. Different from crystallization because distillation collects purified solvent instead of collecting the solute crystals formed Read Career Connect p. 55 Discuss CYU p. 55 #1-4 9
Chapter 3 Review Questions 1) Describe the difference between a mechanical mixture and a solution. (3.1) 2) What are the two parts of a solution? Define each part. (3.1) 3) Brass is a solution made of approximately 80 percent copper and 20 percent zinc. Which part is the solute and which is the solvent? (3.1) 4) If you poured a mixture through a filter, what result would help you identify the mixture as a solution? (3.1) 5) Explain the difference between solubility and concentration. (3.2) 6) If a substance is insoluble, can we describe the concentration of that substance in the solution? Explain. (3.2) 7) You have been provided with four substances: table salt, cooking oil, water, and petroleum jelly. Which combinations will form a solution? Explain why. 8) The concentration of salt in the oceans is about 33 g/l. Explain what this means. (3.2) 10
9) What is the relationship between temperature and solubility? (3.2) 10) Discuss why water is considered the universal solvent, and why petroleum jelly will not dissolve in water. (3.2) 11) Describe the three steps that illustrate how soap works in a washing machine to get your clothes clean. (3.2) 12) Draw a labelled diagram that shows the relationship between crystallization, distillation, and evaporation. (3.3) 13) You are stranded on a boat in the ocean and are becoming dehydrated. You need water to survive. Describe the procedure you could use to get pure water from the salt water in the ocean. (3.3) 14) Describe three ways to make bacteria-infested water safe to drink. (3.3) 11
Complete Chapter 3 Review Questions p. 56 #1-8 Please record your answers below or on an attached sheet of loose leaf. 12