acids

COLOUR CHANGE

SUBSTANCE

CHANGE IN COLOUR

CHARACTERSTICS

VINEGAR

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LIME WATER

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SOAP SOLUTION

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Dil. HCl

BLUE TO RED

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NO CHANGE

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NO CHANGE

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BLUE TO RED

ACIDIC

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NOT ACIDIC

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NOT ACIDIC

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ACIDIC

• Acids react with reactive metals

to form hydrogen gas

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When showing match stick pop sound is

Formed due to presence of hydrogen gas

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Zn+2HCl→ZnCl2​+H2​↑

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• When acids react with carbonates ,carbondioxide gas is liberated

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• Clear lime water turns milky due to presence of carbon dioxide gas

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• CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

Components of acids

Common component is Hydrogen

When hydrochloric acid and nitric acid dissolve in water form oppositely charged ions

Acids are substances which can increase the concentration of hydrogen ions in an aqueous solution

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PROPERTIES OF ACIDS

• Acids have sour taste
• Acids changes blue litmus to red
• Acids react with carbonates to form carbondioxide gas
• Acids react with highly reactive metals to form hydrogen gas

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BASICITY OF ACIDS

The no of hydrogen ions that can be donated by one molecule of an acid is its basicity

ALKALIES

• Burning of Mg ribbon

Mg + O MgO

• Add water to Mg powder ash ,also add red litmus solution- Red changes to Blue

MgO+ H₂0 Mg (OH)₂

Magnesium Hydroxiode

Expereiment no 2

• Quick lime (calcium oxide) + water , then stir it.

take clear solution add red drop of litmus solution

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Red litmus changes to Blue litmus

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CaO + H₂O Ca(OH)₂

• Calcium Hydroxide

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• =

• Are MgO and CaO are metallic oxides or non metallic oxides???

Metallic oxides

Metallic oxides generally exhibit characterstics of bases .The bases that dissolve in water are called alkalies

Find out basic oxides

• K₂0
• SO₂
• P₂O₅
• MgO
• CaO
• NO₂

K₂0

MgO

CaO

FIND OUT THE COMMON FACTORS

• SODIUM HYDROXIDE
• CALCIUM HYDROXIDE
• AMMONIUM HYDROXIDE
• POTTASSIUM HYDROXIDE

• Na OH
• Ca OH
• NH₄OH
• KOH

CHEMICAL NAME

CHEMICAL FORMULA

COMMON FACTOR IS OH

• Observe the equation of dissolution of sodium hydroxiode and calcium hydroxide

NaOH Na⁺ + OH ^-

CaOH Ca ⁺ + OH ^–

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^{COMMON FACTOR –}

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ARRHENIUS THEORY

HCl → H⁺ + Cl^–

KOH → K⁺ +OH^–

H₂CO₃ → 2H⁺ + CO₃^2-� NH₄OH → NH⁺₄ + OH^–�HNO₃ → H⁺ + NO^–₃

� Acids or bases dissolve in water ,

dissociates in to ions

According to Arrhenius theory,

Acids are substances which liberate H+ ions in aqueous solution and bases are substances which liberate OH- ions in aqueous solutions.

NEUTRALISATION REACTION

Acids and alkali react with each other to nullify their individual properties. Such chemical reactions are called neutralisation reactions.

ANTACIDS USED TO REDUCE ACIDICITY

• ANTACIDS – CALCIUM CARBONATE

SODIUM BICARBONATE

ALUMINIUM HY DROXIDE

pH Value

P^H VALUE

Determination of pH value is the scientific method for finding the acidic/ alkaline nature of substances

• pH scale was devised based on the H+ ion concentration in the solution.

Less than 7[Acid]

Greater than 7[ Bases]

NEUTRAL Value

,Washing soda

ACID+ BASE

SALT+ WATER

NaOH + HCl

Nacl + H2O

SALTS

• Na⁺ + OH ^- H ⁺ + Cl ^- Na Cl + H₂O

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_{PRODUCTS FORMED ARE}

NaCl – Sodium chloride

H₂0 - Water

Neutralisation is the process in which alkali and acid react with each other to form salt and water

• Salt are usually ionic compounds

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Mg(OH)₂ + H₂SO₄

MgSO₄ + 2H₂0

Ca(OH)₂ + H₂SO₄ CaSO₄ + 2H₂0

4H ,2 O

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H₂0,H₂O

SALTS DISSOCIATE IN TO POSITIVE IONS AND NEGATIVE IONS WHEN DISSOLVED IN WATER OR WHEN MELTED

NaCl

Na⁺ + Cl^-

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Make salts

• K⁺+ OH^- KOH
• Zn²⁺ + S0₄^2- ZnSO₄
• FeCO₃ — Ferrous carbonate
• CuOH — Cuprous hydroxide

SODIUM –Na⁺ _,SULFIDE- S^{2 -},CHLORIDE – Cl ^-

Calcium ion

Ca²⁺

WRITE POSITIVE AND NEGATIVE IONS

Ca ²⁺ CO₃^2-

FAmmonium hydroxide - (NH₄)₂CO₃

Pottassium nitrate - KNO₃

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• What is the number of positive ions and negative ions in a ‘molecule’ of NaCI?��Positive ions -1, Negative ions- 1
• �What would be the sum of the charges of the positive ions and negative ions in a ‘molecule’ of NaCI?�� 1⁺ + 1^– = 0 (zero)

�Why salts are neutral in nature?��Salts are electrically neutral. The sum of the charge of the positive ions and negative ions in a salt will be zero.

Na⁺ + Cl ^- Na Cl

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What are the method of writing chemical formulae of salts??

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• While writing the chemical formula, first write the symbol of the positive ion and then the symbol of the negative ion.
• Write the numbers indicating the charge of each ion as subscripts after interchanging them.
• Simplify the subscripts and write them in the smallest whole-number ratio.

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Finding chemical formula of compound

• Mg²⁺  PO₄^3-

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2⁺ PO₄

3 ^- Mg

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• Mg₃ (PO₄)₂ -- Magnesium phosphate

QN .NO -2

• Mg ²⁺ CO₃^2-

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• Mg 2^-
• CO₃ 2⁺ Mg ₂ (CO₃)₂

Mg_2/2 (CO₃)_2/2 MgCO₃

find it

• Some positive ions and negative ions are given in the table. Write the name and chemical formulae of the maximum possible salts formed by them.

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1)Calcium chloride CaCl₂�2) Calcium sulphate CaSO₄�3) Calcium phosphate Ca₃(PO₄)₂�4) Ammonium chloride NH₄Cl�5) Ammonium sulphate (NH₄)2SO₄�6) Ammonium phosphate (NH₄)3PO₄

Uses of salts

fertilizers

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• Ammonium sulphate.(NH₄)₂SO₄
• Potassium chloride KCl
• Sodium nitrate NaNO₃

Uses of salts

paris

Review questions

• What is p^H scale?
• How salts are formed ?
• Define salts?
• Name some salts which used as fertilizers ?
• What are the uses of table salt and baking soda ?
• What is the p^H value for acids ,bases and nuetral solution?

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Follow up activities

• A little distilled water is taken in a beaker.?

� A. What is the pH value of the distilled water?

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B. What happens to the pH value when the following substances are added to the water? Justify your answer.� Caustic soda , Vinegar

list the cation and anions of the substance given in the table.