Electrical Conductivity

1. Electrolytes and pH Electrical Conductivity

2. Fact: It is very dangerous to use an electrical appliance near water because of the risk of electrocution. • Is tap water a pure substance, homogeneous mixture (solution) or heterogeneous mixture? • How does water carry an electric current? • Do hydrogen and oxygen molecules conduct electricity? Class starter

3. Tap water is a solution (homogeneous mixture) as it contains dissolved minerals that cannot be seen to the eye. It is the minerals dissolved in water that have a charge and therefore allow an electric current to flow through the solution. Hydrogen and oxygen atoms themselves do not conduct electricity class starter

4. Electrolyte: a substance that when dissolved in water allows an electric current to flow through the solution.example: table salt • Substances that can be dissolved in water but do not conduct electricity are called nonelectrolytes. Example: Sugar • The electrical conductivity of a solution is a measure of its ability to allow an electric current to flow through it. Electrolyte

5. Solutions that contain electrolytes are electrolytic solutions. • Batteries are an example of an electric cell. • these contain an electrolytic solution that conducts electricity between two poles, the electrodes. Electrolytic solutions

6. 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 nonelectrolyticsolution is dissolved, no ions are produced electrolytic dissociation

7. NaCl(s)→Na+ (aq) + Cl-(aq) (s)=solid (aq)= aqueous solution H2O indication that the solute was placed in water electrolytic dissociation of Sodium Chloride H2O

8. The ions formed during electrolytic dissociation conduct electricity • When electrodes connected to a power supply are placed in an electrolytic solution: • Positive ions migrate toward the negative electrode • Negative ions migrate toward the positive electrode Cont...

9. Acid:a compound that produces H+ ion when dissolved in water. Base:a compound that produces OH- ions when dissolved in water. Salt: an ionic compound that forms ions (other than H+ and OH-) when dissolved in water. Types of electrolytes:Acids – Bases - Salts

10. We can easily recognize acids because their molecular formulas start with “H” • Exception to the rule acetic acid...vinegar! CH3COOH • Why? • Doesn`t start with Hydrogen • Acids have a characteristic sour taste. • Common acids: fruit juice, soft drinks, gastric juices Acids

11. We can easily recognize bases because their molecular formula ends with “OH” • Exception Ammonia: NH3 • Edible bases have a bitter taste • Bases are slippery to the touch • Common examples: heart burn medications, cleaning products, blood bases

12. Salts made up of a metal and one or more nonmetals. • Ex: NaCl Na is a highly reactive metal •  Cl is a toxic gas • Not all salts dissolve easily in water • Electrolytic dissociation of salts are important for the proper functioning of our organs. • important to have proper concentration of Mg2+, Ca2+ and K+ in our diets • Salts are also important in maintaining healthy soil Salts

13. IdentifyAcid – Base - Salt

14. IdentifyAcid – Base - Salt

15. Properties of eletrolytes