 Water, Acids and Bases OH MY!

Water  Because of it’s polarity water has three properties that very important.  Temperature Stabilization (Specific Heat)  Cohesion and Adhesion  The Capacity to dissolve substances.

Specific Heat  Specific Heat is the amount of energy needed to raise 1 gram of a substance 1 degree Celsius.  Water will not vibrate very fast until the hydrogen bonds are broken.  So water can take a lot of heat before actually heating up itself.

Water  Water molecules like to stick together.  The hydrogen bonds between molecules do not like to separate meaning that molecules will cling together.  This is called Cohesion

Water  Water molecules also like to stick to other polar surfaces.  This is called Adhesion.  Water can form a layer around certain organic molecules like proteins and act as a protective shield.  This is called a hydration layer.

Water  Water dissolves ions and other polar molecules.  When salt is dumped into water the positive ends of water cluster around the negative ion (chloride) with their negative ends pointing out and other water molecules negative ends cluster around the positive ion (sodium). This creates a barrier between the two ions.

Water  When dissolving substances it is important to know which chemical is the solute and which chemical is the solvent.  Solute = it the solid being dissolved.  Solvent = the substance doing the dissolving.

Acids and Basis  Acids and Basis are nothing more than different concentrations of ions.  An ion is any charged particle.  Cations are positive  Anions are negative.  All Ions are electrolytes.

Acid  Any substance that has extra Hydrogen Ions is an acid.  The more Hydrogen Ions the more acidic.

Basis  When a substance has extra hydroxide ions (OH - ) then it is a base.  The more hydroxide ions the more basic.  (Bases can also be called Alkaline)

Salts  A salt is nothing more than an ionic compound ions other than H + and OH -.  An example is table salt which has a positive NA and a negative Cl.  When they dissasociate they become a single Cation and a single Anion.

pH Scale  The pH scale was created to better compare the relative concentration of Hydrogen ions.  pH stands for partial Hydrogen.  The scale ranges from 0 to 14 and each step is a multiple of 10. The scale is logarithmic.

pH  Example:  Urine generally has a pH of 6 where as water has a pH of 7.  This means that Urine has 10 times more Hydrogen Ions than water.

pH  A pH of 7 is considered neutral.  This means that there as many Hydrogen ions as there are hydroxide ions.  They balance each other out.

Strong or Weak - Acids or Bases that dissociate completely are Strong Acids/Bases. Strong Acids  Acids or Bases that dissociate only partially are Weak Acids/Bases Weak Acids منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS16

Physical Properties of Acids & Bases AACIDS AAcids taste sour (e.g. vinegar, lemon juice). AAcids are harmful to living cells. AAqueous solutions of all acids contain hydrogen ions. AAcid turns blue litmus red. SStrong acids are corrosive. BBASES AAlkalis are taste bitter SStrong alkalis are corrosive. AAqueous solutions of all alkalis contain hydroxide ion. AAlkalis turns red litmus blue. SSoapy touch. منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS17

Neutralization  H +1 + OH -1  HOH  Acid + Base  Water + Salt (double replacement)  Example:  HCl (aq) + NaOH (aq)  HOH (l) + NaCl (aq)  H 2 SO 4 (aq) + KOH (aq)  2 HOH (l) + K 2 SO 4 (aq) منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS18

SALTS  When H + ion of an acid is replaced by a metal ion, a salt is produced e.g.  H 2 SO 4 + 2NaOH  ======  Na 2 SO + 2H 2 O  Here sodium sulphate (Na 2 SO 4 ) is the salt formed. Salts are ionic compounds. منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS19

Methods of making Soluble Salts 1) ACID + METAL  SALT + HYDROGEN 2)ACID + BASE  SALT + WATER 3)ACID + CARBONATE  SALT + WATER + CARBON DIOXIDE منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS20

Types of Salts  Normal Salts:  Normal salts are formed when all the replaceable hydrogen ions in the acid have been completely replaced by metallic ions.  HCl (aq) + NaOH (aq)  NaCl (aq) + H 2 O (l)  H 2 SO 4(aq) + ZnO (aq)  ZnSO 4(aq) + H 2 O (l) منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS21

Types of Salts  Acid salts:  Acid salts are formed when replaceable hydrogen ions in acids are only partially replaced by a metal.  H2SO4 + KOH  KHSO4 + H2O  H3PO4 + NaOH  NaH2PO4 + H2O منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS22

Types of Salts  Basic Salts:  Basic salts contain the hydroxide ion, OH-. They are formed when there is insufficient supply of acid for the complete neutralization of the base. Zn(OH)2 + HCl  Zn(OH)Cl + H2O Mg(OH)2 + HNO3  Mg(OH)NO3 + H2O منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS23

USES OF SALTS S.No. SALTUSE 1Ammonium ChlorideIn torch batteries 2Ammonium NitrateIn fertilizers 3Calcium ChlorideAs drying agent 4Iron SulphateIn Iron tablets 5Magnesium SulphateIn medicine 6Potassium NitrateIn gunpowder etc. 7Silver BromideIn photography 8Sodium ChlorideMaking NaOH 9Sodium StearateIn making soap. منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 منگل، 24 شعبان، 1437 Topic 10: ACIDS, BASES & SALTS24

Homeostasis  Living things can only survive in specific levels of pH.  Homeostasis means to keep things the same or balanced.  To help control the pH a chemical substance can be created called a Buffer.  Buffers help by neutralizing either acids or basis.