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Acids, Bases and Solutions Chapter 7

Acids, Bases and Solutions Chapter 7. Solutions. Notes 7-1 & 7-2. A homogeneous (uniform) mixture that contains a solvent and at least one solute Solvent = dissolves the other substances (Ex. water) Solute = dissolved by the solvent (Ex. salt)

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Acids, Bases and Solutions Chapter 7

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  1. Acids, Bases and SolutionsChapter 7

  2. Solutions Notes 7-1 & 7-2

  3. A homogeneous (uniform) mixture that contains a solvent and at least one solute Solvent = dissolves the other substances (Ex. water) Solute = dissolved by the solvent (Ex. salt) *In solutions, there is more solvent than solute. What is a Solution?

  4. Water is the universal solvent It dissolves more solutes than any other solvents Because its polar (slightly charged) Life depends on water solutions Water is the solvent in blood, saliva, sweat, tears Water

  5. But water is not the only solvent…

  6. Solutions can be formed from any combination of solids, liquids, and gases.

  7. Not all mixtures are solutions. Colloids and suspensions are mixtures that have different properties than solutions. Colloids and Suspensions

  8. When a solution forms, particles of the solvent surround and separate the particles of the solute. Ionic compounds, like salt (NaCl), are separated into individual ions Covalent compounds (molecular compounds), like sugar, are separated into individual molecules Particles in a Solution

  9. Ionic compounds in water conduct electrical current due to the charged ions present Molecular compounds in water usually do not conduct electrical current Electrical Conductivity

  10. Solutes lower the freezing point of a solvent. This is why salt is added to icy roads; it melts the ice and keeps it from refreezing thus making the roads less slippery. Solutes raise the boiling point of a solvent. This is why salt is added to water when boiling pasta; it makes the water hotter thus cooking the pasta faster. Effects of Solutes on Solvents

  11. http://www.youtube.com/watch?v=3G472AA3SEs&feature=related Solutions Song

  12. Concentrated solutions have a lot of solute in the solvent Dilute solutions have a small amount of solute in the solvent Concentration

  13. 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.

  14. Calculating a Concentration • Practice Problem • A solution contains 12 grams of solute dissolved in 36 grams of solution. What is the concentration of the solution? • 33%

  15. Solubility is a measure of how much solute can dissolve in a solvent at a given temperature. If solute continues to dissolve, the solution is unsaturated. If no more solute will dissolve, the solution is saturated. Solubility Which compound is the most soluble?

  16. Temperature and Solubility • The solubility of the compound potassium nitrate (KNO3) varies in water at different temperatures.

  17. Temperature and Solubility • Reading Graphs: • At which temperature shown in the graph is KNO3 least soluble in water? • KNO3 is least soluble at 0ºC.

  18. Temperature and Solubility • Reading Graphs: • At which temperature shown in the graph is KNO3 least soluble in water? • KNO3 is least soluble at 0ºC.

  19. Temperature and Solubility • Calculating: • About how much more soluble is KNO3 at 40ºC than at 20ºC? • KNO3 is about twice as soluble at 40ºC as it is at 20ºC.

  20. Temperature and Solubility • Interpreting Data: • Does solubility increase at the same rate with every 20ºC increase in temperature? Explain. • No; the curve shows that solubility increases more with each 20ºC increase in temperature.

  21. Pressure- increases solubility (soda can) Solvent- some solvents and solutes are not compatible (oil and water), “like dissolves like” Temperature- increases solubility (high temps when cooking) Factors that affect solubility:

  22. ACIDS • Properties: Sour Taste, Corrosive (reacts with metals), Reacts with carbonates to make CO2 gas, Turns blue litmus paper red • BASES • Properties: Bitter taste, Slippery Feel, Turns red litmus paper blue (“Bases turn Blue”) Notes 7-3 and 7-4: Acids and Bases

  23. Acids: Examples: Juice, Vitamin C, Vinegar, HCl Bases: Examples: Ammonia (cleaners), baking soda, soap

  24. Acids in Solutions An acid produces Hydrogen ions (H+) in water Acids in water solution separate into hydrogen ions (H+) and negative ions. In the case of hydrochloric acid, for example, hydrogen ions and chloride ions form: High in Hydrogen Ions (H+), Low in Hydroxide Ions (OH-) Low on the pH scale (pH0-pH7) *pH7= neutral Bases in Solutions A base produces hydroxide ions (OH-) in water When bases dissolve in water, the positive ions and hydroxide ions separate. Look at what happens to sodium hydroxide in water: Not all bases contain hydroxide ions. For example, the gas ammonia (NH3) does not. But in solution, ammonia is a base that reacts with water to form hydroxide ions. Low in Hydrogen ions (H+), High in Hydroxide Ions (OH-) High on pH scale (ph7-pH14)

  25. http://www.youtube.com/watch?v=J9zxjz0bctI Acids and Bases in Solutions

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