Acid Bases And Salts Chapter-2

Acids Bases And Salts Chapter-2

Acids

An acid is a substance that produces hydrogen ions (H+) when placed in aqueous solution .When acids/ ionic compounds are dissolved in water, the ions split apart from each other

(Dissociation)

Properties of Acids

Most acidsTaste sourReact with many metals to form H2 gasAre corrosive Zinc Metal + Hydrochloric Acid ??

Zn (s) + 2 HCl (aq) H2 (g) + ZnCl2 (aq)

Acetic Acid VinegarUsed as a preservativeCarbonic Acid ( H2CO3) or Phosphoric Acid (H3PO4)Found in soft drinksHydrochloric Acid (HCl)Found in our stomachs- aids in food digestionCitric Acid Found in citrus fruitsUsed as a preservativeLactic Acid Found in yogurtProduced by our muscles when they are overworked

Common Acids

bases

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)

Properties of Bases

Most basesTaste bitterFeel slipperyAre corrosive (appears to eat away materials while reacting)Have a chemical formula that ends with OH

Common Bases

AmmoniaCleaners and fertilizers

Sodium hydroxideUsed in soaps and drain cleaners

Magnesium hydroxideAn ingredient found in antacids

Strong/Weak Acids & Bases

When a strong acid/base dissolves in water, nearly all of the acid/base molecules will dissociate into ionsThe 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)With less ions in solution, there is less potential for danger because there are less ions available to react

Hydrogen

Hydrogen

Strong/Weak Acids Examples

Strong Acids 1. HNO3 nitric acid 2. H2SO4 sulfuric acid battery acid 3. HCl hydrochloric acid stomach acid Weak Acids: 1. H3C6H5O7 citric acid citrus fruits 2. HC2H3O2 acetic acid vinegar

Strong/Weak Bases Examples

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

CONCENTRATED AND DILUTE SOLUTION

CONCENTRATED SOLUTION The solution which contain less amount of water [as a solvent] is known as CONCENTRATED SOLUTION .

DILUTE SOLUTION The solution which contain more amount of water [as a solvent ]is known as DILUTE SOLUTION .

Indicators are used to determine if a substance is an acid or a baseAn indicator changes a specific color when in the presence of an acid or a baseLitmus 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

Indicators

pH scale

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)

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

Neutralization

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

Salts

The ions that are left behind after the H+ and OH- ions form water, combine to form a salt.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)

Thank you

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