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Solutions, Acids, and Bases

Solutions, Acids, and Bases. Chapter 8. 8.1 Formation of Solutions. Any State of matter can become part of a solution. For a solution to form, one substance must dissolve in another. Examples: Example: gas dissolves in water, oxygen dissolves in blood, sugar dissolves in tea. Dissolving.

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Solutions, Acids, and Bases

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  1. Solutions, Acids, and Bases Chapter 8

  2. 8.1 Formation of Solutions • Any State of matter can become part of a solution. • For a solution to form, one substance must dissolve in another. • Examples: • Example: gas dissolves in water, oxygen dissolves in blood, sugar dissolves in tea.

  3. Dissolving • SOLUTE dissolves into the SOLVENT Example: Salt is the solute, water is the solvent • Water is always a Solvent • Substances can dissolve in water in 3 ways: • Dissociation • Dispersion • Ionization

  4. Dissolving by dissociation of Ionic Compounds • The solute and solvent particles attract one another. • Example: Saltwater: Water (polar molecule)is attracted to the sodium and chlorine ions and pulls the crystal apart. • This is a physical change

  5. Dissolving by Dispersion of Molecular Compounds • Breaking into small pieces that spread throughout the solvent. • Example: Sugar water: Both sugar and water are polar molecules, so they attract one another. Because water molecules are always moving, they collide frequently with the sugar crystals. The surface sugar molecules break free of the crystal and is pulled into solution. • This is a physical change

  6. Dissolving by ionization of molecular compounds • Neutral molecules gain or lose electrons • Example: When HCl gas dissolves in water, the hydrogen proton from the HCl molecule is transferred to a water molecule forming a hydronium ion H3O+, and a chloride ion, Cl- • This is a chemical change.

  7. Properties of Liquid Solutions • Physical Properties of a solution differ from those of its solute and solvent • Conductivity • Freezing Point and Boiling Point • Heat • During the formation of a solution, energy is either released or absorbed.

  8. Factors Affecting rates of dissolving • Depends on the frequency and energy of collisions that occur between particles of the reactants. • Surface area • Increases possible collisions between solute and solvent • Stirring • Increases likelihood of collisions between solute and solvent • Temperature • Increases movement of particles and increases the energy of the collisions.

  9. 8.2 Solubility • Maximum amount of a solute that dissolves in a given amount of solvent at a constant temperature. • Expressed in grams of solute per 100 grams of solvent at a specified temperature.

  10. Solutions are described as sutured, unsaturated, or supersaturated, depending on the amount of solute in solution. • Saturated Solutions – contains as much solute as the solvent can hold at a given temperature. Addition of more solute will not go into solution. • Unsaturated Solution – has less than the maximum amount of solute that can be dissolved. Addition of more solute will dissolve into solution. • Supersaturated Solutions – contains MORE solute than it can normally hold at a given temperature. Very unstable as extra solute can rapidly deposit our of solution.

  11. Factors affecting solubility • Solubility varies with the solvent used and the conditions of the solution process. • Polarity of the Solvent – like dissolves like • Example: oil will not dissolve in water, but will dissolve using nonpolar soap. • Temperature – the solubility of solids increases as the solvent temperature increases. Gases usually become less soluble as the temperature of the solvent increases. • Example: adding sugar to warm tea instead of cold tea. Carbon dioxide escapes from warm soda faster than cold soda. • Pressure - Increasing the pressure on a gas increases its solubility in a liquid. • Example: pressurized Carbon dioxide in a sealed bottle of soda is released when the bottle is opened (pchhhhh)

  12. Concentration of Solutions • The amount of solute dissolved in a specified amount of solution. • Percent by Volume = Volume of solute x 100% • Volume of solution • Percent by Mass = Mass of solute x 100% • Mass of solution

  13. 8.3 Properties of Acids and Bases • Acid is a compound that produces hydronium ions (H3O+) when dissolved in water. • Proton Donors • Properties: Sour taste, Reactivity with metals , • Color Changes in Indicators (litmus paper) • Base is a compound that produces hydroxide ions (OH-) when dissolved in water. • Proton Acceptors • Properties: Bitter Taste, Slippery Feel • Color Changes in Indicators (litmus paper, phenophthalein)

  14. Neutralization and Salts • Neutralization is the reaction between an acid and a base. The negative ions in an acid combine with the positive ions in a base to produce an ionic compound called a salt. • (H3O + Cl-) + (Na+ + OH-) → (H2O) + (Na++ Cl-) • acid base water salt

  15. 8.4 Strength of Acids and Bases • pH Scale - describe the concentration of hydronium ions in a solution

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