An acid is a substance that produces hydrogen ions (H+) when placed in watero When acids/ ionic compounds are dissolved in

water, the ions split apart from each other (dissociation)

Photo courtesy of:http://www.biologycorner.com/worksheets/acids_bases_coloring.html

Most acids…oTaste souroReact w/many metals to form H2 gasoAre corrosive (appears to “eat away” materials while reacting)oHave a chemical formula that begins with H

Photo Courtesy of:http://healthmad.com/conditions-and-diseases/the-surprising-health-benefits-of-lemons/

Zinc Metal + Hydrochloric Acid ??

Zn (s) + 2 HCl (aq)

Predict the type of reaction based on the reactants!

Single-Displacement

Predict the products of this reaction.

H2 (g) + ZnCl2 (aq)

• Citric Acid o Found in citrus fruits• Used as a preservative

• Lactic Acid o Found in yogurto Produced by our muscles when they are overworked

• Acetic Acid (HC2H3O2)o Vinegaro Used as a preservative

• Carbonic Acid ( H2CO3) or Phosphoric Acid (H3PO4)o Found in soft drinks

• Hydrochloric Acid (HCl)o Found in our stomachs- aids in food digestion

Photo Courtesy of:http://stayinhealth.wordpress.com/2010/02/08/sugary-soft-drinks-increase-pancreas-cancer-risk

A base is a substance that produces hydroxide ions (OH-) when placed in water• When bases/ ionic compounds are

dissolved in water, the ions split apart from each other (dissociation)

Photo courtesy of:http://www.biologycorner.com/worksheets/acids_bases_coloring.html

Most bases…oTaste bitteroFeel slipperyoAre corrosive (appears to “eat away” materials while reacting)oHave a chemical formula that ends with OH

Photo Courtesy Of:http://www.pbs.org/wgbh/nova/body/bitter-taste.html

o Ammonia• Cleaners and fertilizers

o Sodium hydroxide• Used in soaps and drain cleaners

o Magnesium hydroxide• An ingredient found in antacids

Indicators are used to determine if a substance is an acid or a base

An indicator changes a specific color when in the presence of an acid or a base

Litmus Paper: indicator made of a special filter paper that contains dyes extracted from lichens (the crusty “stuff” that grows in rocks) Blue litmus turns red in an ACID

Red litmus turns blue in a BASE Why do you think it’s important to test an

unknown substance with both types of litmus paper?If one type of litmus paper does not change color, that does not

guarantee that the other type of litmus paper will change color (i.e. water)

The pH scale can also help us classify solutions as acids or bases

pH is a measure of the amount of H+ ions in a solution (potential hydrogen)

o The more H+ ions, the lower the pH, the more acidic the solution

7 < pH ≤ 14

Complete the following chart by telling whether the pH represents an acid, base or neutral substance.

Also tell what color each type of litmus paper will turn at that pH level.

pH Acid/Base/Neutral Color of Blue Litmus Paper Color of Red Litmus Paper

2      

8      

4      

7      

13      

When describing acids and bases, strength and concentration do not mean the same thing!

o Strength refers to the ability of the acid/base to dissociate in solution • pH measures this• Dissociation refers to the ability of an ionic compound to break

apart into ions

o Concentration refers to the amount of acid/base dissolved in solution. • An acid or base will have the same pH, regardless of how

concentrated it is• Just because you add water to dilute it, it’s still going to have the

same amount of H+ ions, they’ll just be spread out more

When a strong acid/base dissolves in water, nearly all of the acid/base molecules will dissociate into ionso The greater the ability to dissociate,

the more potential the acid or base has for being dangerous because there are more ions available to react

When a weak acid/base dissolves in water, only a small fraction of the acid/base molecules dissociate (dissociate partially)o With less ions in solution, there is less

potential for danger because there are less ions available to react

Hydrogen

Hydrogen

Strong Acids 1. HCl – hydrochloric acid – stomach acid 2. H2SO4 – sulfuric acid – battery acid

3. HNO3 – nitric acid

Weak Acids: 1. HC2H3O2 – acetic acid – vinegar

2. H3C6H5O7 –citric acid –citrus fruits

Strong Bases: 1. NaOH – sodium hydroxide 2. Any alkali or alkaline earth metal with OH-

(i.e. KOH – potassium hydroxide) Weak Bases: 1. Al(OH)3 – aluminum hydroxide – often found in

deodorants 2. NH4OH – ammonium hydroxide (ammonia) –

used in many cleaning products

Neutralization is a chemical reaction between an acid and a base that takes place in a water solution

When acids and bases react, the H+ ions from the acid react with the OH- ions from the base to form HOH (H2O - water!)

The overall pH becomes “neutral”

Many people that suffer from heartburn will take antacids to ease their symptoms (i.e TUMS). How do you think antacids work?The stomach is acidic due to HCl and antacids are basic. A neutralization reaction occurs!

The ions that are left behind after the H+ and OH- ions form water, combine to form a salto A salt is a compound that forms when the negative ions

from the acid combine with the positive ions from the base

Acid + Base Water + Salt

HCl(aq) + KOH(aq) H2O(l) + KCl(aq)

What type of reaction is a neutralization reaction?Double-Displacement

Name the salt produced in this neutralization reaction.Potassium chloride

  Acid/Base/Salt Color of Blue Litmus Paper Color of Red Litmus Paper

NaOH      

HCl      

Ba(OH)2      

Al(NO3)3      

H2SO4      

Classify each of the following compounds as an acid, base or salt.

Then indicate what color each type of litmus paper will turn when placed in this substance.