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7-2 : Concentration & Solubility

7-2 : Concentration & Solubility. Science Standard 8.5.a: Students know physical processes including freezing and boiling, in which a material changes form with no chemical reaction. . California Standards.

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7-2 : Concentration & Solubility

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  1. 7-2: Concentration & Solubility Science Standard 8.5.a: Students know physical processes including freezing and boiling, in which a material changes form with no chemical reaction.

  2. California Standards • Science Standard 8.5.a: Students know physical processes including freezing and boiling, in which a material changes form with no chemical reaction.

  3. Input • See vocab sheet

  4. Input & Modeling Concentration • To measure concentration, you compare the amount of solute to the total amount of solution. • A concentratedsolutionhas a lot of solute dissolved in a certain amount of solvent. • You can make it more concentrated by adding solute or taking away solvent • A dilutesolutionhas only a little solute dissolved in a certain amount of solvent. • So to dilute a solution you add more solvent • Concentration can be measured as the percent of solute in solution by volumeormass.

  5. Input & Modeling Calculating a Concentration • To calculate the concentration of a solution, compare the amount of solute to the amount of solution and multiply by 100 percent. • For example, if a solution contains 10 grams of solute dissolved in 100 grams of solution, then its concentration can be reported as 10 percent.

  6. Input & Modeling Practice Problem A solution contains 15 ounces of solute dissolved in 60 ounces of solution. What is the concentration of the solution? Calculating a Concentration 15/60 = 0.25 25%

  7. Input & Modeling Solubility • You can identify a substance by its solubility because it is a characteristic property of matter. • Solubility is a measure of how much solute can dissolve in a solvent at a given temperature. • If you can continue to dissolve more solute, you still have an unsaturatedsolution. • If no more solute will dissolve, you have a saturatedsolution.

  8. Input & Modeling Factors Affecting Solubility • Factors that affect the solubility of a substance include pressure, the typeofsolvent, and temperature. • An increaseinpressure increases the solubility of gases. • Ionic and polar compounds usually dissolve in polar solvents – “likedissolveslike” • The solubilityofmostsolidsincreases as temperature increases. • Gasesbecomelesssoluble in a liquid when the temperature of the liquid goes up.

  9. Input & Modeling Factors Affecting Solubility • Pressure • Shaken bottle of soda • “like dissolves like” • Soap and water cleaned with water based paints • Oil paints cleaned with turpentine • Temperature • Solid • Rock/crystal candy (have to heat water up to add more sugar in it and then cool to get sweet candy) • Gas • Warm soda going flat faster (Carbon dioxide escapes faster)

  10. Input & Modeling Temperature and Solubility The solubility of the compound potassium nitrate (KNO3) varies in water at different temperatures.

  11. Input & Modeling Temperature and Solubility Reading Graphs: At which temperature shown in the graph is KNO3 least soluble in water? KNO3 is least soluble at 0ºC.

  12. Input & Modeling Temperature and Solubility Reading Graphs: Approximately what mass of KNO3 is needed to saturate a water solution at 40ºC? Approximately 65 g of KNO3 are needed to saturate a water solution at 40ºC.

  13. 7-3: Describing Acids & Bases What are the properties of acids and bases? Science Standard 8.5.e: Students know how to determine whether a solution is acidic, basic, or neutral.

  14. Anticipatory Set What do these two things have in common? They both have a sour taste because they contain acids.

  15. Input • See vocab sheet

  16. Input & Modeling Properties of Acids & Bases • An acid tastes sour, reacts with metals and carbonates, and turns blue litmus paper red. PROPERTIES: • Sour Taste • Scientist do not use this one to test- too dangerous • Reaction with metals • Acids react with some metals (magnesium, zinc, iron) to produce hydrogen gas • Acids are corrosive

  17. Input & Modeling Properties of Acids & Bases PROPERTIES: • Reaction with carbonates • When mixed with acid it will produce carbon dioxide (gas) • Geologist use this to identify limestone (since it contains carbonates) • Reactions with indicators • Litmus paper is an example

  18. Input & Modeling Properties of Acids & Bases • A base tastes bitter, feels slippery, and turns red litmus paper blue. • COMMON Bases= calcium and sodium hydroxide, and ammonia Properties • Bitter taste • Slippery feel • Be careful touching bases- they can burn your skin • Reaction with indicators • Bases turn Blue

  19. Input & Modeling REMEMBER…

  20. Input & Modeling Uses of Acids & Bases • Acids and bases have many uses around the home and in industry. You can find acids and bases everywhere! • Vitamins (A) • Fertilizers(A) • Car batteries (A) • Cleaning products (B) • Baking soda (B) • Baking soda reacts with acid (such as buttermilk) and creates gases to make things light and fluffy • Mixing cement (B)

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