Notes And Questions For NCERT Class 10 Science Acids Bases Salts

Notes for Class 10

Students should refer to the below Acids Bases Salts Class 10 notes prepared as per the latest curriculum issued by CBSE and NCERT. These notes and questions are really useful as they have been developed based on the most scoring topics and expected questions in upcoming examinations for Class 10. Acids Bases Salts is an important topic in Science Class 10 which if understood properly can help students to get very good marks in class tests and exams.

Acids Bases Salts Class 10 Notes and Questions PDF Download

Read the notes below which will help you to understand all important and difficult topics in this chapter. There are some topics in Acids Bases Salts chapter which you should understand carefully as many questions can come from those parts. Our team of teachers have designed the revision notes so that its helpful for students to revise entire course prior to the class tests.

 Acids                                          Bases
– Sour in taste                              – Bitter in taste
– Change the blue litmus to red      – Change red litmus to blue
– eg.HydrochloricAcidHCl                  eg. SodiumhydroxideNaOH
– SulphuricAcidH2SO4                      PotassiumhydroxideKOH
– NitricAcidHNO3                             CalciumhydroxideCa(OH)2
– AceticAcid CH3 COOH                 – AmmoniumhydroxideNH4OH

♦ Some Naturally occuring acids
Vinegar                           – AceticAcid
Orange                           – CitricAcid
Lemon                            – CitricAcid
Tamarind                        – TartaricAcid
Tomato                           – OxalicAcid
Sour milk (Curd)             – LacticAcid
Ant and Nettle sting        – MethanoicAcid

 Acid – Base Indicators – Indicate the presence of an acid or base in a solution.
 Litmus solution – It is a natural indicator. It is a purple day extracted from Lichens. Other examples are Red Cabbage and coloured petals of Petunia and turmeric.
 Olfactory indicators – Show odour changes in acidic or basic media. eg.onion and clove.
 Acid – Base Indicators

Notes And Questions For NCERT Class 10 Science Chemical Reactions and Equations

 DiluteAcid : Contains only a small amounts of acid and a large amount of water.
 ConcentratedAcid : Aconcentrated acid contains a large amount of acid and a small amount of water.

♦ Chemical Properties of Acids and Bases
Acid + Metal → Salt + Hydrogen
2HCl + Zn → ZnCl2 + H2
2HNO3 + Zn → Zn (NO3)2 + H2
H2SO4 + Zn → ZnSO4 + H2
2CH3COOH + Zn → (CH3COO)2 Zn + H2

 Pop test : When a buring candle is brought near a test tube containing hydrogen gas it burns with a ‘Pop’ sound. This test is conducted for examining the presence of hydrogen gas.
q Base + Metal → Salt + Hydrogen
NaOH + Zn → Na2ZnO2 + H2
                     Sodium Zincate
Note – Such reactions are not possible with all the metals.

♦ Action of Acids with metal Carbonates and metal bicarbonates 
Metal Carbonate + Acid → Salt + Carbondioxide + Water
Na2CO3(s)+ 2HCl(aq) → 2NaCl(aq) + H2O(l) + CO2(g)
Metal bicarbonate + Acid → Salt + Carbondioxide + Water
NaHCO3 + HCl → NaCl + CO2 + H2O

 Lime water Test : On passing the CO2 gas evolved through lime water,
Ca(OH)2 (aq) + CO2(g) → CaCO3(s) + H2O(l)
   Lime water                    White precipitate
On passing excess CO2 the following reaction takes place
CaCO3(s) + H2O(l) + CO2(g) → Ca(HCO3)2 aq
                                             Soluble in water
♦ Neutralisation Reactions
Base + Acid → Salt + Water
NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
Neutralisation reacton takes place when the effect of a base is nullified by an acid and vice versa to give salt and water.

♦ Reactions of metal oxides with acids
Metal Oxide + Acid → Salt + Water
CuO   +              HCl         →    CuCl2 + H2O
Copperoxide   Hydrochloric       Copper + Water
                          acid              chloride

Note : Appearance of blue green colour of the solution because of formation of CuCl2.
Metallic oxides are said to be basic oxides because they give salt and water on reacting with acids.

♦ Reaction of Non Metallic Oxide with Base
Non metallic oxide + Base →  Salt + Water
Ca(OH)2 + CO2 →  CaCO3 + H2O

Note : NonMetallic oxides are said to be acidic in nature because on reacting with a base they produce Salt and Water.
 All acidic solutions conduct electricity
– Glowing of bulb indicates that there is a flow of electric current through the solution.

 Acids or bases in a Water Solution
Acids produce H+ions in the presence of water
HCl + H2O  → H3O+ + Cl
H3O+ – Hydronium ion.
– H+ion cannot exist alone. It exists as H+(aq) or (H3O+) hydronium ion.
H+ + H2O  → H3O+
– Bases provide (OH–) ions in the presence of water

Notes And Questions For NCERT Class 10 Science Chemical Reactions and Equations

All bases donot dissolve in water.An alkali is a base that dissolves in water.
Common alkalis are
NaOH         Sodiumhydroxide
KOH           Potassiumhydroxide
Ca(OH)2    Calciumhydroxide
NH4OH :    Ammonium hydroxide
Note : All alkalis are bases but all bases are not alkalis.

 Precaution must be taken while mixing acid or base with water. The acid must always be added to water with constant stirring as it is highly exothermic reaction.

When an acid or a base is mixed with water they become dilute. This results in the decrease in the concentration of H3O+ or OH– per unit volume in acids and bases respectively.

 Strength of an Acid or Base
Strength of acids and bases depends on the no. of H+ions and OH–ions produced respectively.
With the help of a universal indicator we can find the strength of an acid or base. This indicator is called PH scale.
pH = Potenz in German means power.
This scale measures from 0 (very acidic) to 14 (very alkaline) 7 Neutral
(water in Neutral).
pH paper : Is a paper which is used for measuring PH.
Variation of PH

Notes And Questions For NCERT Class 10 Science Chemical Reactions and Equations

– strongAcids give rise to more H+ions.
eg. HCl, H2SO4 and HNO3.
– Weak Acids give rise to less H+ ions
eg. CH3 COOH, H2 CO3 (Carbonic acid)
– Strong Bases – Strong bases give rise to more OH– ions.
eg. NaOH, KOH, Ca(OH)2
– Weak Bases : give rise to less OH– ions.
eg. NH4OH

♦ More about Salts
Salts and their derivation

Notes And Questions For NCERT Class 10 Science Chemical Reactions and Equations

Note : NaCl and Na2 SO4 belong to the family of sodium salts as they have the same radicals. Similarly NaCl and KCl belong to the family of chloride salts.

Importance of pH in our daily life
 Importance of pH in our digestive system – pH level of our body regulates our digestive system. In case of indigestion our stomach produces acid in a very large quantity because of which we feel pain and irritation in our stomach.To get relief from this pain antacids are used. These antacids neutralises the excess acid and we get relief.
 pH of Acid Rain : When pH of rain water is less than 5.6 it is called Acid Rain.When this acidic rain flows into rivers these also get acidic, which causes a threat to the survival of aquatic life.
 pH of Soil : Plants require a specific range of pH for their healthy growth. If pH of soil of any particular place is less or more than normal than the farmers add suitable fertilizers to it.
 Our body functions between the range of 7.0 to 7.8 living organisms can survive only in the narrow range of pH change.
 Tooth decay and pH : Bacteria present in the mouth produce acids by degredation of sugar and food particles remaining in themouth.Using toothpaste which is generally basic can neutralise the excess acid and prevent tooth decay.
 Bee sting or Nettle sting contains methanoic acid which causes pain and irritation. When we use a weak base like baking soda on it we get relief.
Neutral Salts : Strong Acid + Strong base
               pH value is 7
       eg. NaCl, CaSO4
Acidic Salts : Strong Acid + weak base
               pH value is less than 7
       eq. NH4Cl, NH4 NO3
Basic Salts : Strong base + weak acid
               pH value is more than 7
       eg. CaCO3, CH3 COONa

 Chemicals from Common Salt
– Sodium chloride is called as common salt used in our food. It is derived from seawater.
– Rock Salt is the brown coloured large crystals. This s mined like coal.
– Common Salt is an important raw material for manymaterials of daily use such as.
              Washing Soda
              Bleaching Power.

Preparation : Prepared by the method called chlor-alkali
Called chlor-alkali because we get chlorine and a base in this.
2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(g) + H2(g)

Notes And Questions For NCERT Class 10 Science Chemical Reactions and Equations

 Bleaching Power
Preparation → Ca(OH)2     +    Cl2     →    CaOCl2    + H2O
               calcium hydroxide  chlorine      bleaching    water
uses in textile, factories and laundry, used as disinfectant

 Baking Soda
– Common name – Sodium Hydrogen Carbonate
Preparation NaCl +   H2O +   CO2 +   NH3  →   NH4Cl +    NaHCO3
               Sodium   Water   Carbon   Ammonia             Sodium hydrogen
               chloride              dioxide                                  carbonate

On heating NaHCO3 produces :

Notes And Questions For NCERT Class 10 Science Chemical Reactions and Equations

CO2 produced causes dough to rise and make cakes, pastries spongy.
Uses :     In household, ingredients of antacid
              In making baking power
On heating baking powder produces
NaHCO3 + H+ → CO2 + H2O + Sodium Salt of acid
 Washing Soda
Preparation : Recrystallisation of sodium carbonate
Na2CO3 + 10H2O   Heat →  Na2CO3. 10H2O

– Used in glass, soap and paper industry
– Cleaning agent for domestic purposes.
– Removal of hardness of water.
– Manufacturere of borax.
 Water of crystallisation : Fixed no. of water molecules present in one formula unit of a salt.
– On heating copper sulphate crystals water droplets appear, formula of hydrated copper sulphate – CuSO4. 5H2O.

– gypsum also contains water of crystallisation.
– Formula of gypsum – CaSO4.2H2O
– On heating gypsum at 373k it becomes CaSO4.½H2O is plaster of paris.
– Plaster of Paris is used as plaster for fractured bones.
– When plaster of Paris is mixed with water it changes to gypsum.
CaSO4.½ H2O + 1½ H2O → CaSO4.2H2O
Uses of plaster of Paris :Making toys, decorativematerial and smooth surfaces.

Acids Bases Salts Class 10 notes