Solutions

Solutions Solution  A solution is a homogeneous mixture in which one substance is dissolved in another substance Components of a solution  Two parts of a solution: the substance being dissolved (solute) and the substance doing the dissolving (solvent) Aqueous solution  Solutions in which the solvent is water are aqueous solutions (most common) Tinctures  A solution in which the solvent is alcohol is a tincture Ex: iodine tincture Characteristics of a solution Mixture of two or more substances  light passes through it  particles are uniformly distributed  Ions and dissociation  Ions are atoms with a positive or negative charge Electrolytes  Solutions that conduct electricity are electrolytes (sodium chloride and silver nitrate) Non-electrolytes  Non-electrolytes form solutions that do not conduct electricity (sugar, alcohol, benzene) Questions What is a solution?  What are the two parts of a solution?  What are three properties of a solution?  Questions  What’s the difference between an aqueous solution and a tincture Question  If you wanted to dissolve a substance in water as quickly as possible what could you do? Ways to increase dissolving rate  In order to increase the rate in which a solution dissolves one could heat the solution, stir it, or crush the solute particles Solubility  The measure of how much solute can be dissolved in a solvent is solubility What affects solubility?  The three main factors that affect solubility are temperature, type and the amount of the solvent Effervescence (fizz)  The escape of a gas from a liquid is effervescence (example: soda and alka seltzer) Concentration  Concentration of a solution is the amount of solute that is dissolved in a solvent Concentrated vs. dilute A solution with a lot of solute dissolved is concentrated  A solution with a little solute dissolved is dilute  Types of solutions A saturated solution contains all the solute it can possibly hold  An unsaturated solution contains less solute that is possible  Supersaturated solution  A supersaturated solution can be made to hold more solute than is normal Question  Compare a saturated, unsaturated, and a supersaturated solution Questions What is solubility and what are the three factors that affect it?  What are three ways to increase the rate in which a solute dissolves?  Water Water is the universal solvent  A substance that cannot dissolve in water is insoluble  Polar vs. non-polar A polar molecule has oppositely charged ends (+ and -)  Non-polar molecules have the same charges on its ends  Rule for dissolving solutes in a solvent  Like solutes dissolve in like solvents (polar in polar, non-polar in nonpolar) Hard water vs. soft water Hard water contains dissolved metal ions  Soft water does not contain dissolved metal ions  Freezing point depression  Lowering the freezing point of a solution as a result of the dissolved solute (freezing point depression) Ex: antifreeze in water Boiling point elevation  Raising the boiling point of a substance by adding solute (salt in water) Questions What is the difference between polar and nonpolar molecules?  What is the general rule for dissolving solutes?  Questions What is the difference between hard and soft water?  How does a solute affect the freezing point and the boiling point?  Suspension  A suspension is a heterogeneous mixture in which the solute particles are large enough to be seen (solute is suspended) Colloid  A colloid is a homogeneous mixture that is not a true solution (does not separate, solute remains suspended) Acids  Properties of an acid: sour taste, affecting the color of indicators, turn litmus paper from blue to red, pH 1-6.9 Weak acids vs. strong acids Weak acids (pH 4 - 6.9)  Strong acids (pH about 1-3; common acids: sulfuric, hydrochloric, nitric, and acetic acids  Bases Bases are slippery, bitter taste, turn litmus paper from red to blue  pH 7.1-14  Bases  Common bases potassium hydroxide, calcium hydroxide, sodium hydroxide, and ammonium hydroxide Weak bases vs. strong bases Weak bases (7.1-10.9 pH)  Strong bases (11-14 pH)  pH scale  Measures hydronium ion concentration (strength of the acid or base)  pH scale ranges from 0-14 (7 is the neutral point) water Salt  Salt is a compound formed when an acid is mixed with a base (positive ion from a base and a negative ion from an acid) Neutralization  A neutralization reaction occurs when an acid and a base combine to form salt and water Precipitate  A precipitate is an insoluble substance crystallizes out of solution (ex: salt from a neutralization reaction) Precipitation reaction  The process of forming a precipitate is precipitation Questions What is the pH scale used for?  What is the pH range for an acid, a base?  Questions What are some properties of an acid? Of a base?  Describe neutraliztion.  What is a salt? 