ELECTROLYTES & NEUTRALIZATION

Transcription

1 ELECTROLYTES & NEUTRALIZATION

2 BUT FIRST LET S REVIEW IONS AND BONDING What is the Lewis dot diagram for Magnesium? Mg 2 2- S What is the Lewis dot diagram for Sulfur? How would these 2 elements bond? What charge would each ion have?

3 Remember: ionic bonds are formed through an electrostatic attraction between oppositely charged ions

4 QUICK PRACTICE 1. Draw the Lewis dot diagram to show the bond between sodium and chlorine. Na Na Cl - NaCl Cl

5 QUICK PRACTICE 1. Draw the Lewis dot diagram to show the bond between Lithium and Oxygen. Li O Li Li 2 O Li 2- O

6 SO FAR WE VE LOOKED AT SYNTHESIS OF MOLECULES DISSOCIATION! NOW LET S LOOK AT THE REVERSE

7 Shout out to Mr. Graham for making these super awesome animations! When certain molecules are dissolved in water, they split up into ions.

8 When certain molecules are dissolved in water, they split up into ions.

9 When certain molecules are dissolved in water, they split up into ions.

10 When certain molecules are dissolved in water, they split up into ions. This is called dissociation.

11 The ions can move around in the water, and they carry an electric charge.

12 The ions can move around in the water, and they carry an electric charge. Because of this the resulting solution can now conduct electricity.

13 The ions can move around in the water, and they carry an electric charge. Because of this the resulting solution can now conduct electricity.

14 A solution that conducts electricity due to the presence of ions is called an electrolytic solution.

15 There are three types of electrolytic solutions: Acids Bases Salts

16 Example: Hydrogen chloride An acid is a substance that releases hydrogen ions, H, in solution. HCl

17 An acid is a substance that releases hydrogen ions, H, in solution. Example: Hydrogen chloride HCl HCl HCl

18 Example: Hydrogen chloride An acid is a substance that releases hydrogen ions, H, in solution. HCl H Cl Acids are electrolytic; they will conduct electricity when dissolved in water. HCl HCl

19 Reaction with litmus paper: Cl H H Cl

20 Reaction with litmus paper: ph of an acid is less than 7 Red litmus stays red Blue litmus turns red Cl H H Cl

21 Acids taste sour (if it doesn t kill you) Acids burn They are corrosive

22 Acids can be neutralized by a base Acids react with metals; the reaction releases hydrogen gas, H 2 Example: HCl Mg H 2 MgCl 2

23 Acids can be neutralized by a base Acids react with metals; the reaction releases hydrogen gas, H 2 Example: 2 HCl Mg H 2 MgCl 2 That s nice but it s not balanced

24 Molecular formulas The molecular formula of an acid will appear in one of the following two ways: Start with H HCl HF HNO 3 H 2 SO 4 End with COOH CH 3 COOH C 5 H 7 O 5 COOH These are the exceptions!! Starts with H, but not an acid: H 2 O, H 2 S

25 Example: Sodium hydroxide A base is a substance that releases hydroxide ions, OH -, in solution. NaOH

26 An base is a substance that releases hydroxide ions, OH -, in solution. Example: Sodium hydroxide NaOH NaOH NaOH

27 Example: Sodium hydroxide An base is a substance that releases hydroxide ions, OH -, in solution. NaOH Na OH Bases are electrolytic; they will conduct electricity when dissolved in water. NaOH NaOH

28 Reaction with litmus paper: OH Na OH Na

29 Reaction with litmus paper: Red litmus turns blue ph of a base is greater than 7 Blue litmus stays blue OH Na OH Na

30 Bases taste bitter

31 Bases feel

32 Bases feel soapy / slippery They are caustic

33 Bases feel soapy / slippery Bases can be neutralized by an acid

34 Bases are also known as alkaline solutions The molecular formula of a base: Metal OH NaOH KOH Ca(OH) 2 Exception (doesn t start with a metal): NH 4 OH Mg(OH) 2

35 Example: Sodium chloride A salt is a substance that that is made up of metallic and non-metallic ions. NaCl

36 A salt is a substance that that is made up of metallic and non-metallic ions. Example: Sodium chloride NaCl NaCl NaCl

37 Example: Sodium chloride A salt is a substance that that is made up of metallic and non-metallic ions. NaCl NaCl NaCl

38 Example: Sodium chloride A salt is a substance that that is made up of metallic and non-metallic ions. NaCl Na Cl Salts are electrolytic; they will conduct electricity when dissolved in water. Na Cl Cl Na

39 Reaction with litmus paper: Na Cl Cl Na

40 Reaction with litmus paper: ph of a salt is 7 (neutral) (note: there are exceptions) Red litmus stays red Blue litmus stays blue Na Cl Cl Na

41 Salts (and water) are formed when acids react with bases. (neutralization reaction)

42 Salts taste salty Salts are itchy They are an irritant

43 The molecular formula of a salt: Metal Non-metal(s) NaF CaCl 2 KNO 3 Exception (doesn t start with a metal): Can also start with NH 4 Al 2 (SO 4 ) 3

44 ELECTROLYTES VS NON- ELECTROLYTES Electrolyte Non-Electrolyte Definition Why? Quick Identification Tip Substances that conduct electricity when dissolved in water Because when dissolved in water, ions ( and - charge) are produced. The 1st element will start with a element from group 1, 2 or 3 ex- NaCl Including H Substances that do NOT conduct electricity when dissolved in water Because when dissolved in water, ions are NOT produced. The first element will start with a non-metal (found in groups 4-7) ex- PCl 3

45 WILL IT CONDUCT? Bright Faint Bright Faint No Light

46 Electrolyte? TYPES OF ELECTROLYTES Acid Base Salt Yes Yes Yes Litmus paper Found in: Blue Red BRA fruits, sodas, vinegar, batteries Red Blue Blue = Base Cleaning products blood No change Fertilizers Table salt, bath salts Recognize 1 st element = H Or ends in COOH Metal OH Metal non-metal Examples Exceptions HCl, CH 3 COOH, H 2 SO 4, H 3 PO 4 H 2 O, H 2 S Non-electrolytes NaOH, LiOH NaCl, MgBr 2, Ca(OH) 2, Al(OH) 3 AlPO 3, CaCl 2 C 2 H 5 OH, CH 3 OH

47 PRACTICE

48 ACID, BASE, SALT OR OTHER? Mg 3 P 2 Salt! Name? Magnesium phosphide

49 ACID, BASE, SALT OR OTHER? CH 3 COOH Acid! Name? Acetic acid (or hydrogen acetate)

50 ACID, BASE, SALT OR OTHER? Al 2 S 3 Salt! Name? Aluminum sulphide

51 ACID, BASE, SALT OR OTHER? CH 3 OH Other *Name? Methanol

52 ACID, BASE, SALT OR OTHER? NH 4 OH Base Name? Ammonium hydroxide

53 NEUTRALIZATION

54 RECALL WHAT HAPPENS WHEN AN ACID IS ADDED TO A BASE? Neutralization! When acids and bases are mixed in the right proportions, they neutralize each other creating water and a salt This proportion is dependent on the ph values of each reactant

55 Example I: Acid Base HCl NaOH

56 Example I: Acid Base HCl NaOH - - Remember: when an acid or a base is dissolved in water it undergoes dissociation (splits into its ions)

57 Example I: Acid Base HCl Na OH Na H OH Cl

58 Example I: Acid Base HCl Na OH Na HOH 2 Cl

59 Example I: Acid Base Water Salt HCl Na OH Na H O 2 Cl

60 Example I: Acid Base Water Salt HCl Na OH H O 2 NaCl Neutral

61 Example II: Acid Base HBr LiOH

62 Example II: Acid Base Water Salt HBr LiOH H O Br 2 Li H OH

63 Example III: Acid Base H 2 CO Ca(OH) 3 2

64 Example III: Acid Base Water Salt H 2 CO Ca(OH) H 2 O CaCO 3 H H OH OH

65 Example IV: Acid Base H 2 SO 4 2 KOH H H OH OH? Need another OH

66 Example IV: Acid Base Water Salt H 2 SO 4 2 KOH 2 H 2 O K 2 SO 4 H H OH OH

67 Example V: Acid Base Water Salt?? H 2 O NaF

68 Example V: Acid Base Water Salt H OH H 2 O NaF

69 Example V: Acid Base Water Salt H OH H 2 O NaF