Substances, Mixtures, and Solubility - McGraw-Hill Higher Education

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Start-Up Activities Particle Size and Dissolving Rates Why do drink mixes come in powder form What would happen if you dropped a big chunk of drink mix into the water Would it dissolve quickly Powdered drink mix dissolves faster in water than chunks do because it is divided into smaller particles, exposing more of the mix to the water. See for yourself how particle size affects the rate at which a substance dissolves. 1. Pour 400 mL of water into each of two 600-mL beakers. 2. Carefully grind a bouillon cube into powder using a mortar and pestle. 3. Place the bouillon powder into one beaker and drop a whole bouillon cube into the second beaker. 4. Stir the water in each beaker for 10 s and observe. 5. Think Critically Write a paragraph in your Science Journal comparing the color of the two liquids and the amount of undissolved bouillon at the bottom of each beaker. How does the particle size affect the rate at which a substance dissolves STEP 1 STEP 2 STEP 3 STEP 4 Solutions Make the following Foldable to help classify solutions based on their common features. Fold a vertical sheet of paper from side to side. Make the front edge about 1.25 cm shorter than the back edge. Turn lengthwise and fold into thirds. Unfold and cut only the top layer along both folds to make three tabs. Label each tab as shown. Solid Solutions Liquid Solutions Gaseous Solutions Find Main Ideas As you read the chapter, classify solutions based on their states and list them under the appropriate tabs. On your Foldable, circle the solutions that are acids and underline the solutions that are bases. Preview this chapter’s content and activities at ips.msscience.com 217 Joseph Sohm/ChromoSohm, Inc./CORBIS
What is a solution ■ Distinguish between substances and mixtures. ■ Describe two different types of mixtures. ■ Explain how solutions form. ■ Describe different types of solutions. The air you breathe, the water you drink, and even parts of your body are all solutions. Review Vocabulary proton: positively charged particle located in the nucleus of an atom New Vocabulary substance heterogeneous mixture homogeneous mixture • solution solvent solute • precipitate Substances Water, salt water, and pulpy orange juice have some obvious differences. These differences can be explained by chemistry. Think about pure water. No matter what you do to it physically—freeze it, boil it, stir it, or strain it—it still is water. On the other hand, if you boil salt water, the water turns to gas and leaves the salt behind. If you strain pulpy orange juice, it loses its pulp. How does chemistry explain these differences The answer has to do with the chemical compositions of the materials. Atoms and Elements Recall that atoms are the basic building blocks of matter. Each atom has unique chemical and physical properties which are determined by the number of protons it has. For example, all atoms that have eight protons are oxygen atoms. A substance is matter that has the same fixed composition and properties. It can’t be broken down into simpler parts by ordinary physical processes, such as boiling, grinding, or filtering. Only a chemical process can change a substance into one or more new substances. Table 1 lists some examples of physical and chemical processes. An element is an example of a pure substance; it cannot be broken down into simpler substances. The number of protons in an element, like oxygen, are fixed—it cannot change unless the element changes. Table 1 Examples of Physical and Chemical Processes Boiling Physical Processes Changing pressure Cooling Sorting Burning Chemical Processes Reacting with other chemicals Reacting with light Compounds Water is another example of a substance. It is always water even when you boil it or freeze it. Water, however, is not an element. It is an example of a compound which is made of two or more elements that are chemically combined. Compounds also have fixed compositions. The ratio of the atoms in a compound is always the same. For example, when two hydrogen atoms combine with one oxygen atom, water is formed. All water—whether it’s in the form of ice, liquid, or steam—has the same ratio of hydrogen atoms to oxygen atoms. 218 CHAPTER 8 Substances, Mixtures, and Solubility
Page 1: Substances, Mixtures, and Solubilit
Page 5 and 6: Sugar Water Homogeneous Mixtures Yo
Page 7 and 8: Figure 5 Acetic acid (a liquid), ca
Page 9 and 10: Solubility ■ Explain why water is
Page 11 and 12: Sugar Water How Water Dissolves Mol
Page 13 and 14: Observing Chemical Processes Proced
Page 15 and 16: Figure 13 Concentrations can be sta
Page 17 and 18: Acidic and Basic Solutions ■ Comp
Page 19 and 20: VISUALIZING ACID PRECIPITATION Figu
Page 21 and 22: pH Levels Most life-forms can’t e
Page 23 and 24: Topic: Indicators Visit ips.msscien
Page 25 and 26: Goals ■ Determine the relative ac
Page 27 and 28: Salty Solutions Did you know… ...
Page 29 and 30: acid p. 232 aqueous p. 224 base p.
Page 31 and 32: Record your answers on the answer s

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