Solutions Chapter 8

Objectives Recognize how a solution differs from other types of mixtures Recognize how a solution differs from other types of mixtures Name the different parts of a solution. Name the different parts of a solution. Distinguish how properties of solutions differ from properties of their original components. Distinguish how properties of solutions differ from properties of their original components. Observe in an experiment how to separate the components of a solution. Observe in an experiment how to separate the components of a solution.

Solution Type of mixture, called a homogenous mixture, that is the same throughout. Type of mixture, called a homogenous mixture, that is the same throughout. A solution can be physically separated, but all proportions of a solution have the same properties. A solution can be physically separated, but all proportions of a solution have the same properties.

Solution or Not

Solute A substance that is dissolved to make a solution. When dissolves it separates into individual particles. A substance that is dissolved to make a solution. When dissolves it separates into individual particles.

Solvents A substance that dissolves a solute. A substance that dissolves a solute. DID YOU KNOW???? It is not possible to identify the solute and solvent as different substances when they form a solution!!! It is not possible to identify the solute and solvent as different substances when they form a solution!!!

Types of Solutions Solutes, solvents, and solutions can be gases, liquids, or solids. Solutes, solvents, and solutions can be gases, liquids, or solids. For example, Oxygen is a gas dissolved in sea water. For example, Oxygen is a gas dissolved in sea water.

Types of Solutions Some solutions are in the same physical state. Some solutions are in the same physical state. For example: Vinegar is a solution of acetic acid and water. For example: Vinegar is a solution of acetic acid and water.

Types of Solutions Do solutions ever exists as a solid??? Do solutions ever exists as a solid??? Yes, Bronze is a solid solution in which tin is the solute and copper the solvent. Yes, Bronze is a solid solution in which tin is the solute and copper the solvent. Do solutions exists as gases??? Do solutions exists as gases??? Of course, think about the air we breathe! Of course, think about the air we breathe!

Suspensions In a suspension, the particles are larger than those found in a solution. In a suspension, the particles are larger than those found in a solution. Instead of dissolving they are suspended. Instead of dissolving they are suspended.

Solvent & Solute Particles Interact The parts of a solution—that is, the solute and the solvent—can be physically separated because they are not changed into new substances. The parts of a solution—that is, the solute and the solvent—can be physically separated because they are not changed into new substances. However, individual particles of solute and solvent do interact. However, individual particles of solute and solvent do interact. The solute particles become evenly distributed throughout the solvent. The solute particles become evenly distributed throughout the solvent.

Interaction continued… The way compounds dissolve depends on the type of bonds in the compound. The way compounds dissolve depends on the type of bonds in the compound. Ionic compounds like table salt, split into individual ions. Ionic compounds like table salt, split into individual ions. Covalent compounds like table sugar, dissolve and each molecule stays together and is surrounded by solvent molecules. Covalent compounds like table sugar, dissolve and each molecule stays together and is surrounded by solvent molecules.

Properties of Solvents In every solution—solid, liquid, gas– solutes change the physical properties of a solvent. In every solution—solid, liquid, gas– solutes change the physical properties of a solvent. –Lowering the Freezing Point –Raising the Boiling Point

Lowering the Freezing Point Page 243 Page 243

Raising the Boiling Point Putting salt in water can raise the boiling point. Putting salt in water can raise the boiling point. The amount of salt in the water determines how much the boiling point is increased. The amount of salt in the water determines how much the boiling point is increased. Example for both lowering and raising temperature: Antifreeze! Example for both lowering and raising temperature: Antifreeze! How do you think it works? How do you think it works?

8.2 Objectives Explain how the concentration of a solution varies. Explain how the concentration of a solution varies. Describe how a solute’s solubility can be changed. Describe how a solute’s solubility can be changed. Recognize that solubility depends on molecular structure. Recognize that solubility depends on molecular structure.

Concentration A solution’s concentration depends on the amount of solute dissolved in a solvent at a particular temperature. A solution’s concentration depends on the amount of solute dissolved in a solvent at a particular temperature. Is it easier to make lemonade with or hot or cold water? Is it easier to make lemonade with or hot or cold water?

Degrees of Concentration A solution with a low concentration is a dilute solution. This is done by adding more solvent. A solution with a low concentration is a dilute solution. This is done by adding more solvent. A solution with a high concentration is a saturated solution. It contains the maximum amount solute that can be dissolved in the solvent at a given temperature. A solution with a high concentration is a saturated solution. It contains the maximum amount solute that can be dissolved in the solvent at a given temperature.

Supersaturated Solutions Sometimes solutions contain more dissolved solute than is normally possible. This means it is supersaturated. Sometimes solutions contain more dissolved solute than is normally possible. This means it is supersaturated. This can happen when you raise the solution’s temperature. This can happen when you raise the solution’s temperature. Very Unstable Very Unstable

Solubility The amount of that substance that will dissolve in a certain amount of solvent at a given temperature. The amount of that substance that will dissolve in a certain amount of solvent at a given temperature. Page 247 Page 247

Solubility of a Solute changes! The solubility of a solute can be changed in two ways. The solubility of a solute can be changed in two ways. Raising the temperature Raising the temperature –Most solids are more soluble at higher temps. Change the pressure Change the pressure –The solubility of gases in a liquid solvent increases at high pressure.

Temperature Increase in Temperature: Increase in Temperature: –Solutes dissolves more quickly –Greater amount of solid dissolves in a given amount of solvent. –Page 249

Temperature & Gases The opposite is true for gases—an increase in temperature makes a gas less soluble in water.

Temperature and Solubility Solute Increased Temperature Decreased Temperature Solid Increase is Solubility Decrease in Solubility Gas Increase in Solubility

Supersaturated One way a solution can become supersaturated is through a change in temperature. One way a solution can become supersaturated is through a change in temperature. For example, a solution is saturated at 50 degrees Celsius, and then is allowed to cool slowly. For example, a solution is saturated at 50 degrees Celsius, and then is allowed to cool slowly.

Solubility The solubility of a gas increases at higher pressures and decreases at lower pressures. The solubility of a gas increases at higher pressures and decreases at lower pressures.

Pressure & Solubility Cokes add CO 2 gas at a pressure slightly greater than normal air pressure. Cokes add CO 2 gas at a pressure slightly greater than normal air pressure. When you open the can, the pressure decreases and the Carbon dioxide bubbles out of solution with a fizz! When you open the can, the pressure decreases and the Carbon dioxide bubbles out of solution with a fizz!

Scuba tanks include 79% N. People breathe like this all the time without any problem, but the pressure underwater is much greater than on Earth’s surface. Scuba tanks include 79% N. People breathe like this all the time without any problem, but the pressure underwater is much greater than on Earth’s surface. The higher pressure increases the solubility of N in the diver’s blood. The higher pressure increases the solubility of N in the diver’s blood.

Divers When a diver heads up to the surface too fast, the pressure decreases, and so does the solubility of N. When a diver heads up to the surface too fast, the pressure decreases, and so does the solubility of N. The N comes out of solution and into the diver’s blood. These bubbles can cause painful and sometimes fatal condition called the “bends.” The N comes out of solution and into the diver’s blood. These bubbles can cause painful and sometimes fatal condition called the “bends.”

To Prevent The Bend’s Divers can rise to the surface slowly, so bubbles stay small. Divers can rise to the surface slowly, so bubbles stay small. They can breathe a different mixture of gases, which contains only 66% of N. They can breathe a different mixture of gases, which contains only 66% of N.

Do Oil and Water Mix?

Solubility Water contains polar covalent bonds— containing positive and negative regions. Water contains polar covalent bonds— containing positive and negative regions. Oil molecules are nonpolar– do not contain positive or negative regions. Oil molecules are nonpolar– do not contain positive or negative regions. This means that oil & water are not attracted to each other. This means that oil & water are not attracted to each other.

Water: The Universal Solvent Water is considered essential for life because it can carry so many different ions and molecules. Water is considered essential for life because it can carry so many different ions and molecules.

Review Why will a nonpolar substance not dissolve in a polar substance? Why will a nonpolar substance not dissolve in a polar substance? –Nonpolar solutes do not have a charged regions that would be attracted to charged regions of polar solvents. How does pressure affect the solubility of solids? Of gases? How does pressure affect the solubility of solids? Of gases? –Solid and liquid solutes are not affected by pressure. An increase in pressure increases solubility of gases.

Review What effect does temperature have on most solid solutes? On gases solutes? What effect does temperature have on most solid solutes? On gases solutes? –Increase in temp increases the solubility of most solid solutes. Increase in temp decreases the solubility of gases. What do these terms mean: dilute and saturated? Dilute- low concentration Saturated- Contains maximum amount of solute

Acids, bases and salts Section 3 Chapter 8

Our learning goals for this section: To learn about acids and bases To learn about acids and bases To learn how to determine if a solution is acidic or basic To learn how to determine if a solution is acidic or basic To learn how acids and bases react with each other To learn how acids and bases react with each other

Explore acids and bases What are some observations we can make about this cup of vinegar? What are some observations we can make about this cup of vinegar? What happens when we add 2 crushed alka seltzer tablets? What happens when we add 2 crushed alka seltzer tablets? At the start of the demo looked like water but had a strong smell. After the addition of the alka seltzers the mixture fizzed and bubbles were produced. The vinegar odor was not as strong. So when you have a tummy ache you take an antacid to neutralize the acid being produced by the lining in your stomach.

Acids and Bases Have Certain Properties Acids are found in many foods such as tomatoes, OJ and vinegar. They have a sour taste when dissolved in water and produce a slight tingle to the skin. Acids are found in many foods such as tomatoes, OJ and vinegar. They have a sour taste when dissolved in water and produce a slight tingle to the skin. NEVER TOUCH OR TASTE AN UNKNOWN SUBSTANCE TO SEE IF IT IS AN ACID OR BASE. NEVER TOUCH OR TASTE AN UNKNOWN SUBSTANCE TO SEE IF IT IS AN ACID OR BASE. Bases are the chemical opposites. They taste bitter and feel slippery to the touch. Examples of bases are soaps, ammonia cleaners and antacids. A strong base would be drain cleaner. Bases are the chemical opposites. They taste bitter and feel slippery to the touch. Examples of bases are soaps, ammonia cleaners and antacids. A strong base would be drain cleaner.

It is all about the IONS….. Remember an ion is a charged particle. And if a hydrogen atom loses an electron it becomes a hydrogen ion. Which is simply a proton and has a positive charge. Remember an ion is a charged particle. And if a hydrogen atom loses an electron it becomes a hydrogen ion. Which is simply a proton and has a positive charge. An acid is defined as a substance that can donate a hydrogen ion (a proton) to another substance. An acid is defined as a substance that can donate a hydrogen ion (a proton) to another substance. HCl → H + + Cl - H2OH2O

IONS CONT. A base is a substance that can accept a hydrogen ion from another substance. A base is a substance that can accept a hydrogen ion from another substance. So just generally speaking the difference between an acid and a base is that acids donate protons and bases accept protons. So just generally speaking the difference between an acid and a base is that acids donate protons and bases accept protons. A~D A~D B~A…………….bases B~A…………….bases NaOH → Na + + OH - H2OH2O

Characteristics of acids Tastes sour Tastes sour Strong acids are corrosive and poison Strong acids are corrosive and poison Hydronium ions in all acids Hydronium ions in all acids Variety of changes to indicators Variety of changes to indicators

Characteristics of bases Tastes bitter Tastes bitter Feels slippery Feels slippery Strong bases can be corrosive and poison Strong bases can be corrosive and poison OH - ion present in all bases OH - ion present in all bases

Measuring acid and base strength Strong base and weak base

Strong acid and weak acid

The neutralization process When you have an upset tummy your stomach is producing too much HCl. The pH is about 1.5. You take an antacid that contains a base and the base reacts with the acid to produce a salt and water. When you have an upset tummy your stomach is producing too much HCl. The pH is about 1.5. You take an antacid that contains a base and the base reacts with the acid to produce a salt and water. So an acid + base gives a salt + water. So an acid + base gives a salt + water. Two very harmful things come together to produce two very harmless things. Two very harmful things come together to produce two very harmless things. This is called the neutralization process. This is called the neutralization process.

review Read the summary of the chapter on page 268 Read the summary of the chapter on page 268 Do on page 269 Do on page 269 LET’S PLAY SEARCH AND DESTROY TO REVIEW FOR THE TEST!!!!!!!! LET’S PLAY SEARCH AND DESTROY TO REVIEW FOR THE TEST!!!!!!!!