1. The ammeter measures the flow of electrons (current) through the circuit. If the ammeter measures a current, and the bulb glows, then the solution conducts. If the ammeter fails to measure a current, and the bulb does not glow, the solution is non-conducting.

2. An electrolyte is: A substance whose aqueous solution conducts an electric current. A nonelectrolyte is: A substance whose aqueous solution does not conduct an electric current. Try to classify the following substances as electrolytes or nonelectrolytes…

3. 1.Pure water 2.Tap water 3.Sugar solution 4.Sodium chloride solution 5.Hydrochloric acid solution 6.Lactic acid solution 7.Ethyl alcohol solution 8.Pure sodium chloride

4. ELECTROLYTES:NONELECTROLYTES: Tap water (weak) NaCl solution HCl solution Lactate solution (weak) Pure water Sugar solution Ethanol solution Pure NaCl But why do some compounds conduct electricity in solution while others do not…?

5.  One way to measure the strength of a solution  moles of solute per liter of solution. You must switch all units to moles and liters!  Recall 1000 mL = 1 L Important Notes

7. A. One mole of NaOH has a mass of 40.0 g. If this quantity of NaOH is dissolved in enough water to make exactly 1.00 L of solution, the solution is a 1 M solution. B. If 20.0 g of NaOH, which is 0.500 mol, is dissolved in enough water to make 1.00 L of solution, a 0.500 M NaOH solution is produced.

8.  You have 3.50 L of solution that contains 90.0 g of sodium chloride, NaCl. What is the molarity of that solution? 90.0 g NaCl1 mol NaCl 3.50 L Solution58.44 g NaCl =0.440 M NaCl

9. What is the molarity of a 2.50 L solution that is made from 15.3 g LiCl? How many moles are present in 0.350 L of a 3.20 M solution? How many grams is that? 0.144 M LiCl 1.12 mol

10. The concentration of a solution in moles of solute per kilogram of solvent. Important Notes You must switch all units to moles and kilograms! Recall 1000 g = 1 kg Important Notes

12.  1.25 moles of NaCl is added to 500 g H 2 O, what is the molality? 1.25 mol NaCl 0.500 kg H 2 O =2.50 m NaCl

13. “ Like dissolves like ” Background Information Polar: having an uneven distribution of charge. Nonpolar: a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge.

14.  What makes substances similar depends on the type of bonding (ionic or covalent) and the polarity (polar) or nonpolarity (nonpolar) of molecules between the solute and solvent.

15. Interesting Fact If a warm bottle of soda and a cold bottle of soda are opened, the warm bottle of soda will effervesce more because less gas will be dissolved in the warmer bottle of soda.

16. Warm-up 3/10/15 What does it mean to dilute a solution? Why would it be important to know how to dilute.

17. Dilutions Concentrated Dilute

18. Now we use the equation M 1 V 1 = M 2 V 2 1 is starting (concentrated conditions) 2 is ending (dilute conditions)

19. E.g. if we have 1 L of 3 M HCl, what is M if we dilute acid to 6 L? Why does the formula work? Because we are equating mol to mol: M 1 = 3 mol/L, V 1 = 1 L, V 2 = 6 L M 1 V 1 = M 2 V 2, M 1 V 1 /V 2 = M 2 M 2 = (3 mol/L x 1 L) / (6 L) = 0.5 M M 1 V 1 = 3 mol V 1 = 1 L M 1 = 3 M V 2 = 6 L M 2 = 0.5 M M 2 V 2 = 3 mol

20. Q – What volume of 0.5 M HCl can be prepared from 1 L of 12 M HCl? M 1 = 12 mol/L V 1 = 1 L M 2 = 0.5 mol/L M 1 V 1 = M 2 V 2 M 1 V 1 /M 2 = V 2 V 2 = (12 mol/L x 1 L) / (0.5 M) = 24 L

21. Q – 1 L of a 3 M HCl solution is added to 0.5 L of a 2 M HCl solution. What is the final concentration of HCl? (hint: first calculate total number of moles and total number of L) # mol= (3 mol/L)(1 L) + (2 mol/L)(0.5 L) = 3 mol + 1 mol = 4 mol # L = 1 L + 0.5 L = 1.5 L # mol/L = 4 mol / 1.5 L = 2.67 mol/L

22.  When an ionic substance dissolves in water, the solvent pulls the individual ions from the crystal and solvates them  This process is called dissociation

23.  Substances that dissociate into ions when dissolved in water  A nonelectrolyte may dissolve in water, but it does not dissociate into ions when it does so

24. Soluble ionic compounds tend to be electrolytes

25. Molecular compounds tend to be nonelectrolytes, except for acids and bases

26.  A strong electrolyte dissociates completely when dissolved in water  A weak electrolyte only dissociates partially when dissolved in water

28.  Strong acids (7)

29.  Strong acids  Strong bases (8)

30.  Strong acids  Strong bases  Soluble ionic salts

32. Mix ions that form compounds that are insoluble (as predicted by the solubility guidelines) - a precipitate is formed

33.  Metathesis comes from a Greek word that means “to transpose” AgNO 3 (aq) + KCl (aq)  AgCl (s) + KNO 3 (aq)

34.  Metathesis comes from a Greek word that means “to transpose”  It appears the ions in the reactant compounds exchange, or transpose, ions AgNO 3 (aq) + KCl (aq)  AgCl (s) + KNO 3 (aq)

35.  Metathesis comes from a Greek word that means “to transpose”  It appears the ions in the reactant compounds exchange, or transpose, ions  Also known as “double displacement” reactions AgNO 3 (aq) + KCl (aq)  AgCl (s) + KNO 3 (aq)

36.  It is helpful to pay attention to exactly what species are present in a reaction mixture (i.e., solid, liquid, gas, aqueous solution)  If we are to understand reactivity, we must be aware of just what is changing during the course of a reaction

37. The molecular equation lists the reactants and products in their molecular form AgNO 3 (aq) + KCl (aq)  AgCl (s) + KNO 3 (aq)

38.  In the ionic equation all strong electrolytes (strong acids, strong bases, and soluble ionic salts) are dissociated into their ions  This more accurately reflects the species that are found in the reaction mixture Ag + (aq) + NO 3 - (aq) + K + (aq) + Cl - (aq)  AgCl (s) + K + (aq) + NO 3 - (aq)

39.  To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right. Ag + (aq) + NO 3 - (aq) + K + (aq) + Cl - (aq)  AgCl (s) + K + (aq) + NO 3 - (aq)

40.  To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right.  The only things left in the equation are those things that change (i.e. react and/or change state) during the course of the reaction. Ag + (aq) + Cl - (aq)  AgCl (s)

41.  To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right.  The only things left in the equation are those things that change (i.e. react and/or change state) during the course of the reaction.  Those things that didn’t change (and were deleted from the net ionic equation) are called spectator ions. Ag + (aq) + NO 3 - (aq) + K + (aq) + Cl - (aq)  AgCl (s) + K + (aq) + NO 3 - (aq)

42. 1. Write a balanced molecular equation 2. Dissociate all strong electrolytes to give the complete ionic equation 3. Cross out anything that remains unchanged from the left side to the right side of the equation 4. Write the net ionic equation with the species that remain