Chemistry - Chp 19 - Acids, Bases, and Salt - PowerPoints

Chapter 19 “ Acids, Bases, and Salts ”

Section 19.1 Acid-Base Theories ,[object Object],[object Object]

Properties of Acids ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Properties of Acids ,[object Object],[object Object],[object Object],[object Object],[object Object]

Acids Affect Indicators, by changing their color Blue litmus paper turns red in contact with an acid (and red paper stays red).

Acids have a pH less than 7

Acids React with Active Metals Acids react with active metals to form salts and hydrogen gas: HCl (aq) + Mg (s) -> MgCl 2(aq) + H 2(g) This is a single-replacement reaction

Acids React with Carbonates and Bicarbonates HCl + NaHCO 3 NaCl + H 2 O + CO 2 Hydrochloric acid + sodium bicarbonate salt + water + carbon dioxide An old-time home remedy for relieving an upset stomach

Effects of Acid Rain on Marble (marble is calcium carbonate ) George Washington: BEFORE acid rain George Washington: AFTER acid rain

Acids Neutralize Bases HCl + NaOH -> NaCl + H 2 O - Neutralization reactions ALWAYS produce a salt (which is an ionic compound ) and water. -Of course, it takes the right proportion of acid and base to produce a neutral salt

Sulfuric Acid = H 2 SO 4 ,[object Object],[object Object],[object Object],[object Object]

Nitric Acid = HNO 3 ,[object Object],[object Object],[object Object],[object Object]

Hydrochloric Acid = HCl ,[object Object],[object Object],[object Object],[object Object]

Phosphoric Acid = H 3 PO 4 ,[object Object],[object Object],[object Object],[object Object]

Acetic Acid = HC 2 H 3 O 2 (also called Ethanoic Acid, CH 3 COOH) ,[object Object],[object Object],[object Object]

Properties of Bases (metallic hydroxides) ,[object Object],[object Object],[object Object],[object Object],[object Object]

Examples of Bases (metallic hydroxides) ,[object Object],[object Object],[object Object],[object Object]

Bases Affect Indicators Red litmus paper turns blue in contact with a base (and blue paper stays blue). Phenolphthalein turns purple in a base.

Bases have a pH greater than 7

Bases Neutralize Acids Milk of Magnesia contains magnesium hydroxide, Mg(OH) 2 , which neutralizes stomach acid, HCl. 2 HCl + Mg(OH) 2 MgCl 2 + 2 H 2 O Magnesium salts can cause diarrhea (thus they are used as a laxative) and may also cause kidney stones.

Svante Arrhenius ,[object Object],[object Object],[object Object]

1. Arrhenius Definition - 1887 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Polyprotic Acids? ,[object Object],[object Object],[object Object],[object Object],[object Object]

Acids ,[object Object],[object Object],[object Object]

Arrhenius examples... ,[object Object],[object Object],[object Object],[object Object]

Organic Acids (those with carbon) Organic acids all contain the carboxyl group, (-COOH), sometimes several of them. CH 3 COOH – of the 4 hydrogen, only 1 ionizable The carboxyl group is a poor proton donor, so ALL organic acids are weak acids . (due to being bonded to the highly electronegative Oxygen )

2. Brønsted-Lowry - 1923 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Johannes Brønsted Thomas Lowry (1879-1947) (1874-1936) Denmark England

Why Ammonia is a Base ,[object Object],[object Object],[object Object],[object Object]

Acids and bases come in pairs ,[object Object],[object Object],[object Object],[object Object]

Acids and bases come in pairs ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

3. Lewis Acids and Bases ,[object Object],[object Object],[object Object],[object Object],[object Object]

Section 19.2 Hydrogen Ions and Acidity ,[object Object],[object Object]

Hydrogen Ions from Water ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Ion Product Constant ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The pH concept – from 0 to 14 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Calculating pOH ,[object Object],[object Object],[object Object],[object Object],[object Object]

pH and Significant Figures ,[object Object],[object Object],[object Object]

Measuring pH ,[object Object],[object Object],[object Object]

How to measure pH with wide-range paper 1. Moisten the pH indicator paper strip with a few drops of solution, by using a stirring rod. 2.Compare the color to the chart on the vial – then read the pH value.

Some of the many pH Indicators and their pH range

Acid-Base Indicators ,[object Object],[object Object],[object Object],[object Object]

Acid-Base Indicators ,[object Object],[object Object],[object Object],[object Object],[object Object]

Section 19.3 Strengths of Acids and Bases ,[object Object],[object Object]

Strength ,[object Object],[object Object],[object Object],[object Object]

Strength ,[object Object],[object Object],[object Object]

Strong Acid Dissociation (makes 100 % ions)

Weak Acid Dissociation (only partially ionizes)

Measuring strength ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],(Note that water is NOT shown, because its concentration is constant, and built into K a ) (Note that the arrow goes both directions.)

What about bases? ,[object Object],[object Object],[object Object],[object Object],[object Object]

Strength vs. Concentration ,[object Object],[object Object],[object Object]

Practice ,[object Object],[object Object],[object Object],[object Object]

Section 19.4 Neutralization Reactions ,[object Object],[object Object]

Acid-Base Reactions ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Acid-Base Reactions ,[object Object],[object Object],[object Object],[object Object]

Titration ,[object Object],[object Object],[object Object]

Steps - Neutralization reaction ,[object Object],[object Object],[object Object],[object Object]

Neutralization ,[object Object],[object Object],[object Object],[object Object],[object Object]

Section 19.5 Salts in Solution ,[object Object],[object Object]

Salt Hydrolysis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Salt Hydrolysis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Salt Hydrolysis ,[object Object],[object Object],[object Object],[object Object],NaCl, a neutral salt (NH 4 ) 2 SO 4 , acidic salt CH 3 COOK, basic salt

Buffers ,[object Object],[object Object]

Buffers ,[object Object],[object Object],[object Object],[object Object]

Buffers ,[object Object],[object Object],[object Object]

Buffers ,[object Object],[object Object],[object Object],[object Object],[object Object]

Aspirin (which is a type of acid) sometimes causes stomach upset; thus by adding a “buffer”, it does not cause the acid irritation. Bufferin is one brand of a buffered aspirin that is sold in stores. What about the cost compared to plain aspirin?

Chemistry - Chp 19 - Acids, Bases, and Salt - PowerPoints

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Chemistry - Chp 19 - Acids, Bases, and Salt - PowerPoints