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Chapter 8 8.3 and 8.4 Acids and Bases.

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Presentation on theme: "Chapter 8 8.3 and 8.4 Acids and Bases."— Presentation transcript:

1 Chapter 8 8.3 and 8.4 Acids and Bases

2 Acids Acids are compounds that produce hydronium ions (H3O+) when they dissolve in water.

3 General Properties of Acids
Sour taste Lemons, grapefruits, and vinegar all contain acid. 2. Reactivity with metals Acids and metals undergo a single replacement reaction. Ability to produce color changes in indicators

4 Car batteries, acid rain
Common Acids Name Formula Use Acetic acid CH3COOH Vinegar Carbonic acid H2CO3 Carbonated drinks Hydrochloric acid HCl Stomach acid Nitric acid HNO3 Fertilizer Phosphoric acid H3PO4 Sulfuric acid H2SO4 Car batteries, acid rain

5 Bases Bases are compounds that produce hydroxide ions (OH-) when they dissolve in water.

6 General Properties of Bases
Bitter taste Baking chocolate and cough syrup are bases. Slippery feel Soap is a base. Ability to produce color changes in indicators Phenolphthalein (another indicator) turns red when a base is added. (colorless w/acid)

7 Common Bases Name Formula Uses Aluminum hydroxide Al(OH)3
Deodorant, antacid Calcium hydroxide Ca(OH)2 Concrete, plaster Magnesium hydroxide Mg(OH)2 Antacid, laxative Sodium hydroxide NaOH Drain cleaner, soap

8 FYI Fish contains bases that can leave a bitter taste in your mouth.
Squeezing lemon juice (an acid) over the fish neutralizes the base and gets rid of the bitter taste.

9 Neutralization is the reaction between an acid and a base.
Salt and water are produced.

10 Neutralization (H3O+ + Cl-) + (Na+ + OH-) → 2HOH + (Na+ + Cl-) Acid base → water + salt The negative ions in the acid combine with the positive ions in the base and form a salt (ionic compound). Hydronium ions from the acid combine with hydroxide ions from the base and form water.

11 Common Salts Name Formula Uses Sodium chloride NaCl
Food flavoring, preservative Sodium carbonate Na2CO3 Making glass Potassium chloride KCl Salt substitute Potassium iodide KI Added to table salt to prevent iodine deficiency Magnesium chloride MgCl2 De-icer for roads Calcium carbonate CaCO3 Chalk, marble floors Ammonium nitrate NH4NO3 Fertilizer, cold packs

12 Proton Donors and Acceptors
Acids are proton donors because they produce H3O+ in water. H3O+ has lost an electron. Bases are proton acceptors because they produce OH- in water. OH- has gained an electron.

13 pH Scale 0 to 14 scale ‹ 7 = acid 7 = neutral › 7 = base
Look at figure 22 on page 247 for a visual description.

14 pH Scale The lower the pH the more H3O+ ions the solution contains.
The higher the pH the less H3O+ ions the solution contains.

15 pH Scale Acid or Base pH Item Neutral 7 Distilled water Strong Acid
0.1 Car battery acid Strong Base 10 Soap Weak Acid 6.5 Milk Weak Base 8.5 Baking soda Depends on solutes 6-8 Tap water

16 Strong vs Weak When reactions go to completion rather than reaching equilibrium, strong acids or bases are formed. Strong acid ‹3 Strong base ›10 Weak acids and bases only slightly ionize or dissociate in water. They do not go to completion.

17 Buffers A buffer is a solution that is resistant to large changes in pH. They are made by mixing a weak acid and its salt or a weak base and its salt.

18 Electrolytes An electrolyte is a substance that ionizes or dissociates into ions when it dissolves in water. They conduct electricity well. Strong acids and bases are strong electrolytes because they dissociate or ionize almost completely in water. Electrolytes are found in batteries and fuel cells.


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