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Compounds are classified in different ways

Compounds are classified in different ways. SCIENCE 10. Chapter 5. Chapter 5. Page 218-253. 5.1 Acids and Bases Notes, CYU (odds), RCs, WBook. Lab 5.2 C and 5.2 Quiz To be completed in class only. 8. 7. 6. 5. 3. 2. 1. 4. Labs 5.1A and 5.1B To be completed in class only.

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Compounds are classified in different ways

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  1. Compounds are classified in different ways SCIENCE 10 Chapter 5

  2. Chapter 5 Page 218-253 5.1 Acids and BasesNotes, CYU (odds), RCs, WBook Lab 5.2 C and 5.2 QuizTo be completed in class only 8 7 6 5 3 2 1 4 Labs 5.1A and 5.1BTo be completed in class only 5.3 Organic CompoundsNotes, CYU (odds), RCs, WBook 5.1 QuizIn class Lab 5.3A and 5.3CTo be completed in class only 5.2 SaltsNotes, CYU (odds), RCs, WBook Chapter Test

  3. Class routine 20 minutes PowerPoint Lecture 15 Minutes Workbook 10 minutes Demo Remainder - Lab Time (6 labs) Get organized!!

  4. At Home – Handed in on test day Assignment (all 1 package): • Make Notes for each chapter using the headings foundthroughout the chapter as your section titles • Reading Checks: • Page 225,227,228,238,247 • Check Your Understanding • Page 233, 243, 251 (odd #s) • Understanding Key Ideas • Page 253 #16-23 Get prepared!!

  5. Acids and Bases You are familiar with them! Acids Bases • Stomach acid • Lemons • Grapes • Tomatoes • Vitamin C • Acid Rain • Eggs • Baking Soda • Soap • Bleach • Oven cleaner • Lime *not the fruit!

  6. 5.1 Acids and Bases Bases have a pH above 7. General properties General formulas • Acids usually start with H (hydrogen) on the left of the formula. Ex. HCl • Bases usually have OH (hydroxide) on the right. Ex. NaOH • Water is neutral • H2O has 1 H and 1 OH !!! Water is neutral at pH 7. Acids have a pH below 7.

  7. pH scale pH actually means proportion or power of Hydrogen H+ or the concentration of H+ ions Measures how acidic or basic a solution is One unit of change represents a 10x (times) change in degree of acidity or basicity • pH4 is 100x (2 steps=10 x 10) more acidic than pH6 • pH12 is 1,000,000x (6steps) more basic than pH6 • A small change in pH is a huge change in acidity or basicity A theoretical pOH scale would be the opposite of pH. pH indicators will change colour in the presence of acid and bases.

  8. Acids – pH below 7 Sour, tangy – strong acids are corrosive Acids release H+ ions when dissolved in Water (aq) refers to Aqueous or “dissolved in H2O” Can be named by chemical name: HCl is Hydrogen Chloride Can be named differently if shown with (aq) Ends in “-ic acid” HCl (aq) is Hydrochloric Acid

  9. Acids that contain oxygen -ic vs. -ous Names that begin with Hydrogen and end with –ate • H2CO3 – H2CO3 (aq) • Hydrogen carbonate – Carbonic acid Names that begin with Hydrogen and end with -ite • H2SO3 – H2SO3 (aq) • Hydrogen sulfite – Sulfurous acid

  10. Bases – pH above 7 Bitter-tasting, slippery feel – strong reactive bases are caustic Bases release OH‾ (hydroxide) ions when dissolved in H2O A basic solution is also said to be Alkaline Chemical name ends with hydroxide • NaOH – sodium hydroxide Common names vary • NaOH

  11. Acids and Bases: chemical opposites When an acid is mixed with a base, the solutions can neutralize each other. • If the concentration of H+ is balanced with the concentration of OH‾ the solution is neutral • Acid has more H+ • Base has more OH-

  12. pH indicators An indicator changes colour depending on the pH. • Some common indicators include: • Litmus paper (BAR = Blue + Acid turns red) • Phenolphthalein • Bromothymol blue • Indigo carmine • Methyl orange, • Methyl red

  13. Some household items are indicators Red Cabbage – Lab 5.1A (page 221) • Modified Lab: • Create a pH number scale (#6) • Create an indicator chart for Red Cabbage indicator. • 3. Tape the indicator paper to the chart for 6+ samples • 4. I notice, I Wonder x3each • 5. Name Date & Hand in

  14. Red Cabbage Indicator Pigment responsible: anthocyanin The cabbage is actually PURPLE. Turns GREEN in something basic Turns RED in something acidic Estimate the intensity of the change for your chart… more intense red is more acidic…

  15. Lab 5.1B Page 230 Handing in the following on a sheet of paper Question Data Table Analyze questions *full sentence response Conclude and apply *full sentence response Name Date

  16. Lab 5.2C Page 241 Handing in the following on a sheet of paper Question Data Table Analyze *full sentence responses Conclude and Apply *full sentence responses Name Date

  17. 5.1 Acids and Bases • Many familiar compounds are acids or bases. • Classification as acids or bases is based on chemical composition. • Acids and bases can be very dangerous. • Both can be very corrosive. • NEVER try to identify an acid or base by taste or touch! • The strength of acids and bases in measured on the pH scale. • pH below 7 = acidic, pH above 7 = basic, pH 7 = neutral • 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Acids Neutral Bases • Each decrease of 1 on the pH scale indicates 10× more acidic • For example, pH 4 is 10 times more acidic than pH 5. • pH 3 is 1000 times more acidic than pH 6. See pages 220 - 222 (c) McGraw Hill Ryerson 2007

  18. pH Indicators • The pH of acids and bases cannot be determined by sight. • Instead, pH is measured by other chemicals called indicators or by a pH meter that measures the electrical conductivity of the solution. • pH indicators change colour based on the solution they are placed in. • Litmus is the most common indicator, and is used on litmus paper. • Two colours of litmus paper: Blue = basic and Red = acidic. • Blue = pH above 7, Red = pH below 7. • Universal indicator contains many indicators that turn different colours at different pH values (can be in liquid form, or on paper strips like litmus). • A pH meter uses electrical probes to measure how solutions conduct electricity. • Indicators change colour at different pH values, so different indicators are used to identify different pH values. • Bromothymol blue for pH 6 – 7.6, phenolphthalein for pH 8.2 – 10. • Many natural sources, such as beets and cabbage, are also indicators. Litmus paper See pages 223 - 224 (c) McGraw Hill Ryerson 2007

  19. Acids • If you know a compound’s chemical formula, you may be able to identify whether it as an acid. • Acids often behave like acids only when dissolved in water. • Therefore, acids often are written with symbol (aq) = aqueous = water. • The chemical formula of an acid usually starts with hydrogen (H). • Acids with a carbon usually have the C written first. • HCl(aq) = hydrochloric acid, HNO3(aq) = nitric acid, CH3COOH(aq) = acetic acid • Naming acids • Hydrogen + …-ide = hydro…ic acid • HF(aq) = hydrogen fluoride = hydrofluoric acid • Hydrogen + …-ate = …ic acid • H2CO3(aq) = hydrogen carbonate = carbonic acid • Hydrogen + …-ite = …ous acid • H2SO3(aq) = hydrogen sulphite = sulphurous acid Sulfuric acid is used in batteries. See pages 225 - 226 (c) McGraw Hill Ryerson 2007

  20. Bases • If you know a compound’s chemical formula, you may be able to identify it as a base. • Bases often behave like bases only when dissolved in water. • Therefore, bases are often written with the symbol (aq) = aqueous = water. • The chemical formula of a base usually ends with hydroxide (OH). • Bases can be gentle or very caustic. • Examples of common bases: • NaOH(aq) • Mg(OH)2(aq) • Ca(OH)2(aq) • NH4OH(aq) See page 227 (c) McGraw Hill Ryerson 2007

  21. Production of Ions • Acids and bases can conduct electricity because they release ions in solution. • Acids release hydrogen ions, H+ . • Bases release hydroxide ions OH–. • The pH of a solution refers to the concentration of ions it has. • Square brackets are used to signify concentration, [H+], [OH–] • High [H+] = low pH, very acidic • High [OH–] = high pH, very basic • A solution cannot have BOTH high [H+] and [OH–]; they cancel each other out and form water. This process is called neutraliztion. • H+ + OH– H2O See page 228 (c) McGraw Hill Ryerson 2007

  22. Properties of Acids and Bases Take the Section 5.1 Quiz See page 229 (c) McGraw Hill Ryerson 2007

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