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Solutions

Solutions. Chapter 8. Objectives. Review key principles from previous chapters Recognize how a solution differs from other types of mixtures Name the different parts of a solution. Distinguish how properties of solutions differ from properties of their original components.

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Solutions

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  1. Solutions Chapter 8

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

  3. Things to Remember… PHYSICAL • A change in state is a ______________ change. EX) • Chemical reactions _____________ bonds between atoms • Law of Conservation of mass states that the number of ___________ in the products must equal the number of atoms in the _________________. REARRANGE ATOMS REACTANTS

  4. Things to Remember… COMPOUND • A ______________________ can be created through covalent or ionic bonds. A ________________ can only be created through a covalent bond (EX. Water Molecule). • The temperature at which a liquid becomes a solid is called its _____________________. The temperature at which a liquid rapidly becomes a gas is called its ________________________. MOLECULE FREEZING POINT BOILING POINT

  5. A Solution is a Type of MIXTURE • A solution is actually a ___________________ mixture because it is the same throughout, but a solution CAN be _________________ by physical means. The substances in a mixture DO NOT ____________ ____________. • All proportions of a solution have the _________ _____________. HOMOGENOUS SEPARATED REACT CHEMICALLY SAME PROPERTIES

  6. Solution or Not Kool-Aid is a SOLUTION!!!!! Water (by itself) is not a solution, but we can use water to make different solutions.

  7. Solute SOLUTE A. The ____________________ is a substance that is dissolved to make a solution. When it dissolves it separates into _______________ ______________. INDIVIDUAL PARTICLES

  8. Solvents SOLVENT WATER B. The __________________ is a substance that dissolves a solute. ______________ is the most commonly used solvent (We even call it the “Universal Solvent”) DID YOU KNOW???? • It is not possible to identify the solute and solvent as different substances when they form a solution!!!

  9. SOLUTESDISSOLVE IN SOLVENTS

  10. Types of Solutions 4. Solutions can be SOILD, LIQIUD, or GAS. • For example, Oxygen is a gas dissolved in sea water. • Page 240

  11. Types of Solutions • Some solutions are in the same physical state. • For example: Vinegar is a solution of acetic acid and water. • A. If solutions are in the same state of matter (EX. 2 Liquids), the substance present in the greatest amount is considered to be the ______________________. SOLVENT

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

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

  14. 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. • However, individual particles of solute and solvent do interact. • The solute particles become evenly distributed throughout the solvent.

  15. Interaction continued… • The way compounds dissolve depends on the type of bonds in the compound. • 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.

  16. Properties of Solvents • In every solution, solutes change the physical properties of a solvent: • They always ___________________ the freezing point (Adding salt to roads during snow storms) • They always___________________ the boiling point (Adding antifreeze to your car) LOWER RAISE

  17. Lowering the Freezing Point • Page 243

  18. Raising 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. • Example for both lowering and raising temperature: Antifreeze! • How do you think it works?

  19. Suspensions SUSPENSION 7. In a ___________________, the particles are larger than those found in a solution. EX) Suspensions are not ______________. FLOUR IN WATER SOLUTIONS

  20. 8.2 Objectives • Explain how the concentration of a solution varies. • Describe how a solute’s solubility can be changed. • Recognize that solubility depends on molecular structure.

  21. Concentration A solution’s CONCENTRATION depends on the amount of solute dissolved in a solvent at a particular temperature. EX) “Orange Juice Concentration” simply means how much juice is dissolved into water.

  22. Concentration Can Vary • A DILUTE solution has a low concentration of solutes (It has a higher level of solvents) • A SATURATED solution has a high concentration of solutes (It has a lower level of solvents) • You can raise the concentration by adding more SOLUTES or decrease the concentration by adding more SOLVENTS. • A SUPER SATURATED solution contains more solutes than is normally possible.

  23. SOLUBILITY 9. The SOLUBILITYof a substance is the amount of the substance that will dissolve in a certain amount of a solvent at a given temperature • If the solute is highly soluble, a saturated solution will be very CONCENTRATED. • If a solute has a low solubility, the saturated solution will be DILUTE.

  24. Changing Solubility • We can change the solubility of a solute. There are two different ways: • To dissolve more solid into a liquid, we simply raise the TEMPERATURE. The solid will dissolve quicker and more of it will dissolve in a given solvent. • To dissolve more gases into a liquid, we must increase the PRESSURE. Increasing the temperature of a gas will actually make it less soluble.

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

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

  27. Pressure & Solubility • Cokes add CO2 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!

  28. 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.

  29. Divers • 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.”

  30. To Prevent The Bend’s • 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.

  31. Temperature and Solubility

  32. This is how we make SUPER SATURATED solutions!

  33. Supersaturated Solutions

  34. Concentration • 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?

  35. Solubility Depends on Molecular Structure • When a substance dissolves, the molecules separate from one another and become evenly mixed • A POLAR substance attracts a POLAR substance to form solutions. • “Like dissolves like” • PAGE 251

  36. What Would Happen???? • What would happen if I mixed water, oil and corn syrup in the same bottle?

  37. Do Oil and Water Mix?

  38. Review • 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? • Solid and liquid solutes are not affected by pressure. An increase in pressure increases solubility of gases.

  39. Review • 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

  40. Acids, bases and salts Section 3 Chapter 8

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

  42. Acids & Bases Basics 12. Acids and Bases are formed when solutions are dissolved in WATER. When they dissolve they produce an ION, or charged particle. ******EX) If a hydrogen atoms loses its electron, it becomes positive (it’s actually just a PROTON.) 13. Acids and bases are classified based on their ability to either accept or donate these hydrogen ions (or PROTONS)

  43. How do we measure acids & bases • pH scale (pg 258)

  44. 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. • An acid is defined as a substance that can donate a hydrogen ion (a proton) to another substance. H2O HCl → H+ + Cl-

  45. IONS CONT. • 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. • A~D • B~A…………….bases NaOH → Na+ + OH- H2O

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

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

  48. Not all acids and bases are alike. They can vary in STRENGETH. • -When a STRONG ACID is dissolved in water, it separates almost completely into ions (H+). • -When a WEAK ACID is dissolved in water, it does not form many ions. • -When a STRONG BASE is dissolved in water, it separates almost completely into ions (OH-) • -When a WEAK BASE is dissolved in water, it does not form many ions. • **PAGE 256 for examples

  49. Strong acid and weak acid

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