Electrolytes and pH

 Electrolyte: a substance that when dissolved in water allows an electric current to flow through the solution. Example: table salt  Some substances can be dissolved in water but do not conduct electricity called nonelectrolytes. Example: Sugar  Electrical conductivity of a solution is a measure of its ability to allow an electric current to flow through it.

 Solutions that contain electrolytes are electrolytic solutions.  Batteries are an example of an electric cell.  Containing an electrolytic solution that conducts electricity  Batteries conduct electricity between two poles

 A physical change; the separation of a dissolved compound into two ions of opposite charges  Example: Sodium chloride (NaCl) dissociates into Na + and Cl -  If sodium chloride dissolves in water, all of its properties are conserved  When a nonelectrolyte solution is dissolved, no ions are produced

NaCl (s) →Na + (aq) + Cl -  (s)=solid  (aq)= aqueous solution  H 2 O indication that the solute was placed in water H2OH2O

 Ions conduct electricity  Electrodes connected to a power supply in an electrolyte solution  Positive ions migrate toward the negative electrode  Negative ions migrate toward the positive electrode

 Acids: A compound that produces H + ion when dissolved in water. We can easily reconize acids because their molecular formulas start with “H”  Base: A compound that produces OH - ions when dissolved in water. We can easily recognize bases because their molecular formula ends with “OH”  A salt is an ionic compound that forms ions (other than H + and OH - ) when dissolved in water. We will work with neutral salts

 Common acids: fruit juice, soft drinks, gastric juices  Exception to the rule acetic acid...vinegar! CH 3 COOH  Why?  Doesn`t start with Hydrogen

 Common examples: heart burn medications, cleaning products, blood  Usually begins with a metal and ends with OH  Exception Ammonia: NH 3

 Salts made up of metal and one or more nonmetal  Not all salts dissolve easily in water  Electrolytic dissociation are important to us!  Vital to survival

AcidHCl SaltAl 2 S 3 SaltKNO 3 BaseKOH BaseCa(OH) 2 AcidHNO 3 AcidH 2 SO 4

AcidBaseNeutral Salt Electrical Conductivity Conducts Taste/FeelSourBitter/slipperysalty pH<7>77 Reaction to Litmus Paper Turns redTurns blueNo reaction Reaction to cobalt chloride paper Turns pinkish Reaction with metalProduces H 2 No reaction Reaction with carbonnates Produces CO 2 No reaction