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Substances, Mixtures, Solubility

Substances, Mixtures, Solubility. What is a Substance?. Substance -. matter that has a fixed composition. -can’t be broken down by physical processes. Chemical -Burning -Reacting with chemicals -Reacting with light. Physical -Boiling -Change pressure -Cooling -Sorting.

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Substances, Mixtures, Solubility

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  1. Substances, Mixtures, Solubility What is a Substance?

  2. Substance- matter that has a fixed composition. -can’t be broken down by physical processes

  3. Chemical -Burning -Reacting with chemicals -Reacting with light Physical -Boiling -Change pressure -Cooling -Sorting

  4. Examples of substances Elements- Atoms of different kinds - Different #’s of protons Ex. O, S, C, Fe, Au etc. Compounds- Substances made of 2 or more elements chemically combined - Fixed composition (atomic ratios) Ex. H2O, NaCl ex. H2O is always H2O not H3O or H2O2

  5. Mixtures- • Made of 2 or more substances (mixed together) • CAN BE separated physically • CAN BE put together in any proportion

  6. 2 Types of Mixtures Heterogeneous Mixture- different throughout Homogeneous Mixture- same throughout (solution)

  7. Solution- Evenly mixed on a molecular level but NOT bonded together Ex. Saltwater

  8. 2 Parts of a Solution Solute – gets dissolved Ex. salt Solvent- does the dissolving Ex. Water

  9. Types of Solutions Gaseous Solutions Liquid Solutions Solid Solutions

  10. Liquid Solution- -Solute can be: A solution having a liquid solvent Solid – salt water Liquid – vinegar & water Gas - pop

  11. Gaseous Solution- 2 or more gases in solution Ex. Air

  12. Solid Solution- -Melt it , Mix it, Coooooool it down 2 or more solids in solution Ex. Steel = Iron + Carbon Alloy- 2 or more metals in solution Ex. Brass = Copper + Zinc

  13. Solubility WATER!! Aqueous Solution- The Universal Solvent = A solution where water is the solvent.

  14. Molecular Compounds - This means that they share electrons (Covalent Bond) • If the electrons are not shared equally the molecule is POLAR • (has a + & - end) Compounds = Chemically Bonded Ex. H2O

  15. Ionic Bonds Atoms with a charge (because they’ve gained or lost electrons) - Loses an electron Gains an electron e Ion - Na + Cl - Bonds Together (opposites attract)

  16. How Water Dissolves Ionic Compounds - + H O Positive Ion H + - Negative Ion

  17. How Water Dissolves Molecular Compounds H2O gets in between the molecules (separating them) Ex. Sugar (also a polar molecule)

  18. What Will Dissolve? -Polar molecules dissolve polar molecules Ex. H2O & sugar - Nonpolar molecules dissolve nonpolar molecules Like Dissolves Like!! Oil – Nonpolar H2O - Polar they don’t go into solution

  19. How Much Will Dissolve? Describes how much solute dissolves in a solvent (at a given Temp). Solubility- (High Solubility - Lots of solute dissolves Low Solubility – Little solute dissolves Insolubile – Very little or NO solute dissolves)

  20. Rate of Dissolving 1. Raise the Temperature 2. Stirring - Speed it up by: 3. Crush the Solute

  21. 1. Raise the Temperature Increases molecule movement Mix faster

  22. 2. Stirring - Puts fresh solvent in contact with solute

  23. 3. Crush the Solute Exposes more surface to solvent More solvent contact

  24. Making Solutions Dilute Concentrated Saturated

  25. Dilute - Describes a solution made by dissolving a small amount of solute in a large amount of solvent.

  26. Concentrated - -Describes a solution made by dissolving a large amount of solute in a solvent. -may be a limit at a certain temperature

  27. Saturated - -Describes a solution that has all the solute that it can hold without changing conditions. Temp. = amount of solute SUPER SATURATED

  28. Acidic & Basic Solutions Substances that release positively charged hydrogen ions (H+) in water. Acids- H+ combines with H2O = H3O+

  29. Properties of Acids 1. Sour taste NEVER TASTE 2. Conducts electricity ex.Battery acid 3.Corrosive- can break down certain substances ex. Fabric, paper, skin 4. Solutions can react strongly with some metals

  30. Uses:Acid: Salad dressing acetic acid Citrus fruits citric acid Vitamin C ascorbic acid Ants formic acid Pickling, steal, paint, sulfuric acid Fertalizers, plastics sulfuric acid Cleaning hydrochloric acid Fertilizers, dyes, nitric acid plastics

  31. Acids and the Environment Cave formation – Carbonic Acid ( CO2) in the soil is dissolved in H2O) - Can dissolve limestone (calcium carbonate)

  32. Acids and the Environment • Sulfur dioxide and nitrogen oxides are released into the air - power plants etc. • These react with H2O in the air to form nitric acid and sulfuric acid • When it rains = Acid Rain ACID RAIN:

  33. Acidic & Basic Solutions Substances that accept hydrogen ions (H+). When bases dissolve in H2O: Bases- H2O looses H+ = OH - hydroxide ion + O H O - = H H H

  34. Properties of Bases 1. Bitter taste NEVER TASTE 2. Feels slippery - soap 3.Corrosive- can break down certain substances ex. Burns, tissue damage 4. Contains ions - Conducts electricity - does not react with metals like acids

  35. Uses:Base: Soaps OH- interacts strongly Cleaning products with dirt and grease. Oven cleaner ex. Lye sodium hydroxide Chalk blood Lime - CaOH - marks lines on sports fields

  36. What is pH? Basic Acidic 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH- a measure of how acidic or how basic a solution is. Most Acidic Ex. Hydrochloric Acid (HCL) Most Basic Ex. Sodium Hydroxide (NaOH) Neutral

  37. The pH scale- 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 One pH unit represents a TENFOLD change in the acidity 100 x more basic 10 x more acidic

  38. Strengths of Acids & Bases Basic Acidic The weaker the acid, the higher the pH ex. Food The stronger the acid, the lower the pH ex. Dangerous burns 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Neutral

  39. -The strength is related to the number of H+ ions it donates • Lower pH • H+ donated Hydronium ions H3O+ = Acid strength

  40. Indicators- Ex. Cabbage Juice Compounds that react with acidic or basic solutions producing certain colors depending on the solutions pH. • Ex. Litmus – soaked into paper strips • Turns --- RED in Acid • --- BLUE in Base

  41. Neutralization- Ex. Antacid (Magnesium Hydroxide (Mg(OH)2) • How Neutralization Occurs The interaction between H+ of an acid and OH- of a base to form H2O and salt. • H3O+ + OH- 2 H2O H O H H O O O H H H H pH =7 neutral H

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