Check Your Understanding 6.1 1. a) Solubility is a measure of the amount of a solute that will dissolve in a solvent at a certain temperature. b) How can you determine the solubility of a solid in water? Continue to dissolve the solid, a little at a time, until no more will dissolve. Record the amount that has dissolved, and express the result in grams per 100g of water. 2. a)In figure 6.2, the solid substance that is the most soluble in water is sugar. b) In figure 6.2, the gas that is the most soluble in water is carbon dioxide. c) Using the particle theory of matter to compare sugar and carbon dioxide; the particles of each pure substance are alike, but the particles of sugar are different from the particles of carbon dioxide. The particles of sugar attract each other, as do the particles of carbon dioxide. The particles of carbon dioxide have more freedom and are moving faster than the particles of sugar, however. 3. a) The substance the most soluble in water in figure 6.2 is ethyl alcohol. b) The substance insoluble in water in figure 6.2 is canola oil. c) Using the particle theory of matter to compare the substance: there is a great deal of attraction between the particles of ethyl alcohol and water. When canola oil and water are combined, the particles of oil are more attracted to one another than the water particles. 4. Examples of 5 materials that are insoluble in water are: flour, glass, plastic, ceramic, and metal. Check Your Understanding 6.2 1. "Rate of dissolving" is the speed at which a solute dissolves in a solvent. 2. a) Three factors that can affect the rate at which a solid dissolves in a liquid are the size of the solute crystals, agitation of the liquid and solute, and the temperature (heating) of the solvent. b) Size of the cup or the container. 3. Matter is made of particles that have spaces between them. The particles are constantly moving. When there are smaller solute particles,thereis more surface area exposed to the solvent. When the mixture is agitated (stirred), the mothion of the particles is increased, and the attractive force of the solvent pulls in the solute particles more quickly. The effect of heating the solvent is similar to the effect of agitation. 4. a) Two factors that affect the solubility of a solid in a liquid are the temperature of the liquid and the solvent used. b) Increasing the temperature increases the amount of solute that will dissolve. The solvent that is used can either raise or lower the solubility, depending on the combination of the solute and sovent, and the degree of attraction between the particle 5. a)Heating reduces the solubility of a gas in a liquid. b)Pressure increases the solubility of a gas in a liquid. 6. Hot water can dissolve more sugar than cold water because the hot-water particles are moving faster and are farther apart, allowing more spaces in-between for the sugar particles. Therefore, more water particles come in contact with more sugar particles. 7. a) Examples include oxygen, carbon dioxide, sugar, salt, some dyes, alcohol, and vinegar. b) Examples may include plastic, rubber, glass, ceramics, wood, fabrics, and oil. 8. Rock salt would stay on snowy or icy roads longer than table salt because the crystals are larger. The small crystals of table salt would dissolve more quickly. As well, the wheels on passing vehicles agitate the salt crystals, making them dissolve even faster. 6.3 Check Your Understanding 1. Two natural mixtures from this chapter are petroleum and gold ore. 2. a) Petroleum is an oily liquid mixture found deep below Earth's surface. b) Petroleum is difficult to remove because it is found in small, sponge-like holes in the rock. 3 a) A petroleum refinery is a factory that processes the petroleum to separate it into its different components. b) the process used to refine petroleum is called fractional distillation. Students' sketches should show the two towers, one short and one tall, that are used in refineries. Students should indicate that the petroleum is vaporized in the first tower and distilled and condensed in the second tower, at different levels for different products. 4. a) Sand and gravel are mixed in with the gold nuggets. b) Such a mixture is likely to be found where gold ore is exposed to running water. The gold is so soft that it washes out of the rock and forms nuggets. The nuggets may travel a great distance from the original deposit. c) When the mixture is washed and panned, the gold nuggets have more mass than the rock or sand, so they stay behind in the pan while the rock and sand are washed away. 5. a) Gold ore is a mixture of white quartzite rock and gold. The gold is embedded in the quartzite. The solid gold mixture in question 4 is found as loose nuggets. It is not embedded. b) After the gold particles have been dissolved, the components of the solution are separated by a chemical process that makes the solvent bind with zinc and leave the gold behind.