Unit 5 Lesson 1 Solutions Copyright © Houghton Mifflin Harcourt Publishing Company

Mix It Up What is a solution? Unit 5 Lesson 1 Solutions Mix It Up What is a solution? A solution is a homogeneous mixture in which two or more substances are so completely blended and evenly distributed that you cannot identify the different parts. A solution may be solid, liquid, or gas. Light passes through gas and liquid solutions, so you can see through them. Particles in solutions are so small that they cannot be trapped and separated by a filter. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 5 Lesson 1 Solutions What is a solution? Not all mixtures are solutions. A colloid contains medium-sized particles that are distributed in a gas, liquid, or solid. The particles are large enough to scatter light passing through the mixture but small enough not to settle or be separated by a filter. In a suspension, large particles are distributed in a gas or liquid. The particles do not dissolve, so they block light and the mixture appears cloudy. Particles eventually settle out of a suspension, or they can be separated out by a filter. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 5 Lesson 1 Solutions What is a solution? Which image shows a colloid, which a solution, and which a suspension? Copyright © Houghton Mifflin Harcourt Publishing Company

What are the two parts of a solution? Unit 5 Lesson 1 Solutions What are the two parts of a solution? Solutions have two parts: the solute and the solvent. The solute is the substance that is being dissolved in a solution. A solute can be a liquid, gas, or solid. The solvent is the substance in the solution that does the dissolving. A solvent can also be a liquid, gas, or solid. Water is the most common liquid solvent. Copyright © Houghton Mifflin Harcourt Publishing Company

What are the two parts of a solution? Unit 5 Lesson 1 Solutions What are the two parts of a solution? As a solution forms, solute particles become evenly distributed in the solvent. A homogeneous mixture is formed. After a solution forms, it is not possible to visibly distinguish between the solute and the solvent. Copyright © Houghton Mifflin Harcourt Publishing Company

Concentrate! How can the concentration of a solution vary? Unit 5 Lesson 1 Solutions Concentrate! How can the concentration of a solution vary? The measure of the amount of solute dissolved in a solvent is called concentration. One way to calculate the concentration of a solution is to divide the mass of the solute by the volume of the solvent. The units of concentration are often expressed as grams per milliliter (g/ml). Copyright © Houghton Mifflin Harcourt Publishing Company

How can the concentration of a solution vary? Unit 5 Lesson 1 Solutions How can the concentration of a solution vary? A dilute solution contains a small amount of solute in a given volume of solvent. A concentrated solution contains a large amount of solute in a given volume of solvent. A saturated solution contains the most solute that can be completely dissolved in a given amount of a solvent at a given temperature and pressure. If more solute is added to a container of a saturated solution, it will settle to the bottom without dissolving. Copyright © Houghton Mifflin Harcourt Publishing Company

How can the concentration of a solution vary? Unit 5 Lesson 1 Solutions How can the concentration of a solution vary? Raising the temperature of a saturated solution often allows more solute to dissolve. If the solution is cooled very slowly, the extra solute might stay dissolved. This type of solution is said to be supersaturated. A supersaturated solution is very unstable. If even a single crystal of solute is added, all the extra solute will quickly solidify, so that it is no longer dissolved in the solution. The result is often the formation of beautiful crystals of the solute. Copyright © Houghton Mifflin Harcourt Publishing Company

What factors affect solubility? Unit 5 Lesson 1 Solutions What factors affect solubility? The solubility of a solute is its ability to dissolve in a given amount of solvent at a certain temperature and pressure. An increase in temperature has two effects on most solid solutes—they dissolve more quickly, and a greater amount can be dissolved in a given amount of liquid solvent. The opposite is true for gases—an increase in temperature makes a gas less soluble in water. Copyright © Houghton Mifflin Harcourt Publishing Company

What factors affect solubility? Unit 5 Lesson 1 Solutions What factors affect solubility? Pressure changes do not usually change the solubility of solids or liquids. However, the solubility of a gas increases at higher pressures and decreases at lower pressures. Copyright © Houghton Mifflin Harcourt Publishing Company

What helps solids dissolve faster in liquids? Unit 5 Lesson 1 Solutions What helps solids dissolve faster in liquids? When a solid dissolves in a liquid, the particles of the solid separate and spread out among the particles of the liquid until the solid is evenly distributed throughout the liquid. You cannot see any solid particles in the final solution. An increase in temperature, an increase in surface area, and an increase in motion can all help a dissolving solid to dissolve more quickly. Each method helps the solid particles separate and spread out among the liquid particles. Copyright © Houghton Mifflin Harcourt Publishing Company

What helps solids dissolve faster in liquids? Unit 5 Lesson 1 Solutions What helps solids dissolve faster in liquids? Heating a mixture can help a solid dissolve very quickly in a liquid. Crushing increases the surface area of solute that is exposed to the liquid solvent. Crushing helps solids dissolve faster. Solids also dissolve faster when you stir or shake a mixture. Copyright © Houghton Mifflin Harcourt Publishing Company