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Mixtures, Solutions, and Water

Unit 7A. Mixtures, Solutions, and Water. Types of Mixtures. Review: When we classified matter, we learned that mixtures can be classified as: Homogeneous (visually the same throughout) or Heterogeneous visually different throughout)

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Mixtures, Solutions, and Water

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  1. Unit 7A Mixtures, Solutions, and Water

  2. Types of Mixtures Review: • When we classified matter, we learned that mixtures can be classified as: Homogeneous (visually the same throughout) orHeterogeneous visually different throughout) • What are some examples of each of these types of mixtures?

  3. Suspension: a heterogeneous mixture of 2 or more substances • Particles arelargeenough to settle out and can be separated byfiltering i.e. – Muddy water

  4. Flour suspended in water (appears light blue because blue light is scattered off the flour particles to a greater extent than red light) • Other examples: • Chalk Dust suspended in the air • Paint

  5. Colloid Colloids:homogeneous mixture of 2 or more substances evenlyblended into one another. • Substances neverseparate (settle out)

  6. What’s the difference between a solution and colloid? Use the: Tyndall Effect Colloidshavelargerparticlesthatscatter light;Solutionshavesmallerparticlesthat do not scatter the light Is fog a solution or colloid?

  7. A solution is... Def. - A homogenous mixture of two or more substances The Formation of a solution is a physical change …NOT a chemical change.

  8. Parts of a Solution Solvent:component presentin thelargestamount(usually H2O). • Solute:the substance that is being dissolved • Present in the smallest amount

  9. Types of Liquid Solutions Aqueous • A solution with water as the solvent Tincture • A solution with alcohol as the solvent

  10. 100 g. 100 g. 5 g 35 g Solution Concentration • Refers to the amount of solute dissolved in a solvent 5 grams of salt in 100 grams of water dilute VS 35 grams of salt in 100 grams of waterconcentrated

  11. Concentrated vs. Dilute SUMMARY • A concentrated solution contains: Large amount of SOLUTE in a small amount of SOLVENT • A dilute solution contains: Small amount of SOLUTE dissolved in a large amount of SOLVENT “from concentrate”

  12. Does a solution always have to a be liquid? NO!!

  13. Solid into a Solid (alloy):two metals dissolved into one another. Solid into a Liquid:Salt dissolved in water. Examples of Solutions Gas into a Liquid:CO2 dissolved (under pressure) into a coke.

  14. Argon, CO2, and other trace gases 20.95% Oxygen 78.09% Nitrogen The air that we breathe is also a solution because it is made up of many different gases. The “solvent”

  15. Day 2 – Solubility Graphs

  16. Dissolving Def: the process of creating a solution through the mixing of solute and solvent particles Can a solute be dissolved by any solvent? NO!!

  17. Insoluble When a substance cannot be dissolved in a solvent... = don't mix + water Oil The word soluble refers to solutes that CAN be dissolved in a particular solvent.

  18. The Exxon Valdez Oil Spill of 1989

  19. Solubility • A measure of how much solute can be dissolved in a solvent under certain conditions (i.e. – temp. & pressure) Example can be dissolved in: How much ?

  20. A solution can be described as: Limits of Solubility Unsaturated: more solute can be dissolved in the solvent Saturated: the maximum amount of solute has been dissolved in the solvent Supersaturated:more solute has been dissolved than is normally possible http://boyles.sdsmt.edu/supersat/AlexanderOnly.asx

  21. Solubility Graphs Saturated Unsaturated

  22. Shows the relationship between temperature and solubility Any point directly on the line = Saturated Any point below the line = Unsaturated

  23. Dissolving Rate • Def. – The amount of time required for a solvent to dissolve a particular solute • “Speed of dissolving”

  24. Dissolving Rates (Solid in a Liquid & Gas in a Liquid)

  25. Three Factors Affecting Dissolving Rate of a Solid into a Liquid: 1. Temperature 2. Stirring 3. Surface Area

  26. Temperature • Increasing the temperature causes an increase in kinetic energy of the solid solute and liquid solvent particles • As the particles move faster, they collide into each other more, thereby increasing the DISSOLVING RATE

  27. Stirring • Stirring also increases dissolving rate • Stirring causes an increase in collisions between the particles in a solution

  28. Surface Area • Def. – A measure of how much exposed area a substance has • Breaking, crushing, etc. are ways to increase the Surface Area • Increasing surface area allows more solute to come into contact with the solvent; increases dissolving rate VS.

  29. Solubility of Gases • Depends on: • Pressure = solubility • Temperature= solubility • Stirring = solubility Pressure has the greatest effect on the solubility of a gas in a liquid!

  30. Effervescence • The escape of a gas from a liquid solution

  31. Day 4 – Water, Electrolytes, and Ionic Solutions

  32. Wateris a polar molecule that can dissolve many solutes. - - O O H H H H + + + + Water is the "Universal Solvent" Hydrogen Bonds: the (+) end of one water molecule attracts a (-) end of another.

  33. Polar Molecules • Def. – molecules with ‘charged’ regions due to the electronegativity of the elements • Compare hydrogen and oxygen in the water molecule • One side of a water molecule is slightly negative and the other is slightly positive.

  34. Is oil polar???????? Will oil dissolve into water? Polar solventsdissolvepolarsolutes. Why do you need soap to clean butter off a knife?

  35. - + “Like Dissolves Like” • The charged ends of a polar solvent can separate the charged ends of a polar solute. • Nonpolar molecules – have an equal sharing of electrons between atoms Is vinegar polar or non-polar? Is salt polar or non-polar?

  36. Cl- Na+ Cl- Na+ Cl- Na+ Cl- Na+ Na+ Cl- Na+ Cl- Ionization • The formation of ions by solvent as it separates the solute particles in a solution • When you pour NaCl (salt) into water, ions are formed • Na+ or Cl-

  37. Electrolytes • A solution in which the solute has dissolved to create ions. • These dissolved ions allow the solution to conduct electricity.

  38. Types of Electrolytes • NONELECTROLYTE – formed by solutes that DO NOT dissociate into ions in solution • STRONG ELECTROLYTE – formed by solutes that COMPLETELY dissociate in solution • WEAK ELECTROLYTE – formed by solutes that DO NOT COMPLETELY dissociate in solution

  39. Why is it dangerous to use electric appliances around bathwater? Distilled Water is pure water with NO dissolved salts or minerals.

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