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Acids and Bases

Acids and Bases. Science 10. Acid. In an aqueous solution, acids produce hydrogen H + ions Example: hydrochloric acid, HCl, which is found in our stomachs. In water the acid will produce H + and Cl - ions. HCl (aq)  H + (aq) + Cl - (aq). Characteristics of Acids. Sour taste

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Acids and Bases

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  1. Acids and Bases Science 10

  2. Acid In an aqueous solution, acids produce hydrogen H+ ions Example: hydrochloric acid, HCl, which is found in our stomachs. In water the acid will produce H+ and Cl- ions. HCl (aq)  H+(aq) + Cl- (aq)

  3. Characteristics of Acids • Sour taste • Can burn the skin • Conducts electricity • Reacts with metals to produce hydrogen gas (H2) • Neutralizes a base • Reacts with carbonate and bicarbonate to produce carbon dioxide gas (CO2)

  4. Examples of Acids • Lemons • stomach acid • acid rain • battery acid • vinegar

  5. Bases • In an aqueous solution a base produces hydroxide OH- ions • Example: sodium hydroxide (NaOH). In water this base produces Na+ and OH- ions. NaOH(aq)  OH-(aq) + Na+(aq)

  6. Characteristics of Bases • Bitter taste • Slippery texture • Can burn skin • Conducts electricity • Neutralizes acids • Reacts with certain metals (like Al) to produce hydrogen gas (H2) • Does not react with carbonates

  7. Examples of Bases • Bleach • baking soda • Soap • Windex • tonic water

  8. Acid or Base? • H2CO3  H+ + CO32- • Ca(OH)2  Ca2+ + OH- • NH3 + H2O  NH4+ + OH- • KOH  K+ + OH-

  9. pH scale pH: the measure of the acidity of a solution. • The scale ranges from 0 to 14. • 0 – 6 = acid • 7 = neutral (distilled water) • 8 – 14 = base

  10. Most acids and bases are clear and colorless. You need an indicator to tell them apart. • Indicator: a chemical that changes color as the concentration of H+ or OH- changes. • There are many different indicators such as Litmus, phenolphthalein and even cabbage juice!

  11. Litmus Test • Red and blue litmus paper • Acids turn blue litmus paper red. • Bases turn red litmus paper blue • Neutral substances will not change the colour of red OR blue litmus paper. A good tip = BRA (blue to red in an acid) Source: http://cahm.nbed.nb.ca/Science/science61d.htm

  12. pH Paper • You compare the colour with a given chart • Instead of telling you whether something is an acid or a base it gives you the exact pH. Source: http://escalade.nbed.nb.ca/images/ex15.jpg

  13. Other Indicators • Phenolphthalein • Turns bright pink in bases, at pH of 8.2 or higher • Will be clear in acids • Cabbage Juice • A homemade indicator • Turns a rainbow of colors based on various pH levels

  14. Neutralization Reactions • An acid and a base react together to form a new compound. • The general equation is: Acid + Base → Salt + Water • Example: HCl + NaOH → NaCl + H2O

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