Presentation is loading. Please wait.

Presentation is loading. Please wait.

General Chemistry Spring 2010

Similar presentations

Presentation on theme: "General Chemistry Spring 2010"— Presentation transcript:

1 General Chemistry Spring 2010
ACIDS AND BASES UNIT 10 General Chemistry Spring 2010

2 The Importance Of acids… Blood is controlled by buffers
Citrus fruits (citric acid) Vinegar (acetic acid) Vitamin C (ascorbic acid) Aspirin (acetyl salicylic acid) Car batteries (sulfuric acid)

3 The Importance Of bases… Baking soda Milk of magnesia
Antacids have carbonates, bicarbonates and hydroxides to neutralize acids Ammonia (cleaning products) Sodium hydroxide, aka: lye (oven and drain cleaner)

4 How do you know you have…
An acid? Produces H+ in water Blue litmus paper turns red Sour taste Reacts on metal pH less than 7 Metal etched using acid

5 How do you know you have…
A base? Produces OH- ions in water (hydroxide ions) Red litmus paper turns blue Slippery feel Bitter taste (taste shampoo tomorrow morning) pH higher than 7

6 pH Means “potency of hydrogen”
Refers to pondus hydrogenii (potential hydrogen)

7 The pH Scale

8 Arrhenius Acids Substance that ionizes in water to produce hydrogen ions (H+) “ionization”- process by which covalent compounds form cations and anions Ex) HCl  H Cl-

9 Arrhenius Base Substance that dissociates in water to release hydroxide ions (OH-) “dissociation”- process by which ionic compounds separate into ions Ex) NaOH  Na OH-

10 Neutralization Reactions
An acid neutralizes a base to yield a salt and water. Example A) Hydrochloric acid reacts with sodium hydroxide to give the salt sodium chloride and water. HCl NaOH  NaCl H2O Different acids yield different salts, but water is always a product

11 Neutralization Reactions
Example B) H2SO NaOH  Na2SO H2O The hydrogen ion (H+) from the acid is neutralized by the hydroxide (OH-) ion from the base. These two ions combine to form water.

12 Identifying an Acid and Base
Each salt is composed of the cation (+) from the reacting base and the anion (-) from the acid. Predict the acid and base that produce the following salts: Potassium acetate, KC2H3O2 Let’s see some steps first.

13 Predicting Acids and Bases
Split the salt formula into ions Which ion gets H+? Write the formula Which ion gets OH-? Write the formula Potassium acetate, KC2H3O2 KOH + HC2H3O2  KC2H3O2 + HOH OPPOSITES ATTRACT!

14 Predicting Acids and Bases
Lithium fluoride, LiF HF LiOH  Li F H2O

15 The pH Scale Revisited What is pH again?
It expresses the acidity of a solution; the concentration of hydrogen ions Ranges from… 0  14 As pH decreases, the concentration of hydrogen ions increases, and the concentration of hydroxide ions decreases. In a neutral solution, the concentration of hydroxide ions and hydrogen ions are equal.

16 Acid-Base Indicators Methyl Red Color change ~pH 5 Below pH 5: red
Above pH 5: yellow At 5? Orange (only a portion has been converted from yellow to red)

17 Acid-Base Indicators Bromthymol blue Color change ~pH 7
Below pH 7: yellow Above pH 7: blue At 7: greenish

18 Acid-Base Indicators Phenolphthalein Color change ~ pH 9
Below pH 9: colorless Above pH 9: pink At pH 9: very light pink

Download ppt "General Chemistry Spring 2010"

Similar presentations

Ads by Google