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Dissolving Substances can dissolve in water three ways: –Dissociation –Dispersion –Ionization Solute – what is being dissolved Solvent – the substance in which the solute dissolves
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Solutions, Acids, and Bases
Chapter 8
Section 8-1
• Formation of Solutions
Dissolving
• Substances can dissolve in water three ways:– Dissociation– Dispersion– Ionization
• Solute – what is being dissolved• Solvent – the substance in which
the solute dissolves
Dissociation
• Dissociation – process in which an ionic compound separates into ions as it dissolves.
Dispersion
• Dispersion – breaking into smaller pieces that spread throughout the water.
Ionization
• Ionization – the process in which neutral molecules gain or loose electrons (and form ions).
Properties of Liquid Solutions
• The three physical properties of a solution that can differ from those of its solute and solvent are – Conductivity– Freezing Point– Boiling Point
Heat of Solution
• During the formation of a solution, energy is either released or absorbed.
• The process is either endothermic or exothermic.
Rates of Dissolving
• Factors that affect the rate of dissolving include– Surface area– Stirring– Temperature
Section 8-2
• Solubility and Concentration
Solubility
• Solubility – the maximum amount of a solute that dissolves in a given amount of solvent.
• Solutions are described as saturated, unsaturated, or supersaturated depending on the amount of solute in solution.
Solubility
• Saturated solution – one that contains as much solute as the solvent can hold at a given temperature.
• Unsaturated Solution – a solution that has less than the maximum amount of solute that can be dissolved.
Solubility
• Supersaturated Solution – one that contains more solute than it can normally hold at a given temperature. These solutions are very unstable.
Factors Affecting Solubility
• The factors that affect the solubility of a solute are – Polarity of the solvent (like
dissolves like)– Temperature– Pressure
Concentration of Solutions
• Concentration can be expressed as– Percent by volume– Percent by mass– Molarity
Percent by Volume
Volume of soluteVolume of solution
x 100%
Percent by Mass
Mass of soluteMass of solution x 100%
Molarity
Molarity = Moles of soluteLiters of solution
Summary
• How are solutions with different amounts of solute described?
• What factors determine the solubility of a solute?
• What are three ways to measure the concentration of a solution?
Section 8-3
• Properties of Acids and Bases
Properties of Acids
• Some general properties of acids include– Sour taste– Reactivity with metals– Ability to produce color changes in
indicators• Indicator – any substance that
changes color in the presence of an acid or base.
Properties of Bases
• Some general properties of bases include– Bitter taste– Slippery feel– Ability to produce color changes in
indicators
Neutralization and Salts
• Neutralization – the reaction between an acid and a base.
• The neutralization reaction between an acid and a base produces a salt and water.
Neutralization and Salts
Example: HCl + NaOH NaCl + H2O
• Since all acids have H (hydrogen) ion and all bases have OH (hydroxide) ion, when the two mix, they make water and an ionic compound (known as a salt).
Proton Donors and Acceptors
• Acids can be defined as proton donors, and bases can be defined as proton acceptors.
How is an acid a proton donor?
All acids contain an H (hydrogen) ion.
+
e-
Summary• What are some general
properties of acids and bases?
• What are the products of neutralization?
• What are proton donors and proton acceptors?
Section 8-4
• Strength of Acids and Bases
The pH Scale
• The lower the pH value, the greater the H3O+ ion concentration.
• The higher the pH value, the lower the H3O+ ion concentration.
Strong Acids & Bases
• When strong acids dissolve in water, they ionize almost completely.
• Strong bases dissociate almost completely in water
Electrolytes
• Electrolyte – a substance that ionizes or dissociates into ions when it dissolves in water.
• Resulting solution can conduct electricity.
• Strong acids and bases are strong electrolytes because they dissociate or ionize almost completely in water.