NCERT CLASS 10-2021- METALS AND NON METALS -CHAPTER-3-PART 1-PHYSICAL PROPERTIES OF METALS AND NON METALS

 

CLASS 10 METALS AND NON METALS -CHAPTER-3-PART 1-PHYSICAL PROPERTIES OF METALS AND NON METALS

PHYSICAL PROPERTIES OF METALS

Think about some metals which you use and find in daily life like iron, silver, gold, aluminium, copper and also some non-metals which you see in daily life like carbon and oxygen.

Let us discuss the physical properties of the metals just by performing certain activities.

• METALLIC LUSTRE

 Take some pieces of iron, copper, aluminium, magnesium, lead and zinc. Rub these metals with sandpaper and see what happens.

What do you see? You will find that these metals have a shining surface. This shining surface which the metals have is called metallic lustre. So it is a peculiar property of the metals. Metals have metallic lustre or metals have shining surfaces.

METALLIC LUSTRE

• HARDNESS

 You must have seen that most of the metals are very hard and strong. But there are certain exceptions also. Some metals like sodium and potassium are very soft and if you want to cut these metals with a knife you will be able to cut it.

• PHYSICAL STATE

 Metals are generally solids. Think about the metals like silver, gold, copper or aluminium. All are solids, but there is an exception- mercury is a metal which is a liquid at room temperature.

• MALLEABILITY

An activity can be performed. Take some metals like aluminium, copper, silver or gold.  Place it on an iron block and hammer it. What do you see? You will get a sheet on hammering and this property is called malleability. So malleability is an ability of the metals to be beaten into thin sheets. Most of the metals can be beaten into thin sheets.

You must be very fond of eating the sweets and have you ever noticed the silver foils over the sweets. So these are made of silver. Silver can be beaten into thin foils. Aluminium foil is used for packing the foods. Gold and silver are the most malleable metals.

aluminium package

• DUCTILITY

You must have seen the wires of aluminium and copper.  Ductility is the ability of the metals to be drawn into thin wires. That is why metals are used to make the wires because they can easily be drawn into thin wires. From one gram gold about two kilo meter long wire can be drawn. Most ductile metal is gold. 

•  CONDUCTORS OF HEAT

An activity can be performed to study the next property of metals. This activity can be performed in the lab.

Fix a metal wire with the help of a stand and fix a pin with the help of wax.  Place a burner at one end of the wire and heat the wire.  What do you observe?  You will find that this pin falls down.  Why? The heat is being conducted to this and off the wire due to which the wax melts and the pin falls down. What does it show?  It shows that metals allow the heat to pass through them. So most of the metals are good conductors of heat.

You have seen the cooking utensils in the house. What is the material used to make the cooking utensils? Generally cooking utensils are made of metals because metals are good conductors of heat. Best conductors of heat are silver and copper. Lead and Mercury are poor conductors of heat.

• CONDUCTORS OF ELECTRICITY

Another activity can be performed next. Take a battery and connect it to a conducting wire and a bulb is placed in the circuit. There is a switch and the metal which is to be tested is inserted in the circuit.  Different metals are taken and they are tested. When all these metals copper, aluminium iron, silver and gold are placed in this space to complete the circuit, it is found that the bulb grows.  What does it show?  The glowing of the bulb shows that all these metals allow the current to pass through them.

 All the metals are good conductors of electricity. That is why the metals are used to make electric wires .

copper wire and insulated wire

You must have seen the electric wires which are used in the houses. They are generally coated by a layer of either rubber or PVC poly vinyl chloride because you must be very well aware of this that rubber and PVC are insulators. They do not allow the electric current to pass through them and so a person who is handling these electric wires can be saved from electric shock.

• SONOROUS

You must have seen the bell in your school. On hitting it with a hammer it produces a ringing sound. This property is known as sonority and the metals are said to be sonorous. The metals that produce a sound on striking a hard surface are said to be sonorous.

• HIGH MELTING POINT AND BOILING POINT

Metals have very high melting points and boiling points. They melt at very high temperature except for sodium and potassium. Another exception is gallium and cesium which melt on taking over the palm.

• DENSITY AND COLOUR

Metals have very high densities except sodium and potassium.

Now let us see the colour of the metals. You must have seen that most of the metals are either silver or grey in colour but there are certain metals which have different colours. copper is reddish brown in colour and gold is shining yellow in colour.

 

PHYSICAL PROPERTIES OF NON- METALS

Collect various samples of different non-metals which you can easily get and study their physical properties as you studied the properties of the metals. You can collect non-metals like graphite, sulphur and phosphorus.

Non-metals do not possess lustre. The lustre is present only in the case of metals. They do not possess a shining surface. Observe the surface of the nonmetals you will find that the non-metals do not possess a shining surface like metals. Non-metals have a dull surface except diamond and iodine, which have a lustrous surface.

Non-metals cannot be beaten into thin sheets nor can be drawn into thin wires. So non-metals are neither malleable nor ductile. If you beat them with the hammer non-metals will break into pieces. Non-metals are brittle.

Non-metals are neither good conductors of heat nor good conductors of electricity. But there are exceptions like graphite which is a good conductor of electricity. Graphite contains carbon. It is used to make  batteries. So graphite conducts electricity very well.

 Non-metals are soft. Unlike metals which are very hard, nonmetals are soft. But there are exceptions like diamond.  Diamond is the hardest substance.

diamond

Diamond and graphite both are forms of carbon. They are called allotropes of carbon.  They are different physical forms of carbon with different physical properties but same chemical properties.

 Most of the non-metals are solids or gases. Oxygen is a gas, hydrogen is a gas, sulphur is a solid, graphite is a solid,but bromine is a liquid.

Unlike metals, non-metals have low melting points and boiling points except diamond which has a high melting point.

Non-metals have low densities.

The colour also varies in the case of non-metals. They have different colours. Sulphur is yellow in colour, phosphorus is white or red colour,  graphite is black in colour and bromine is orange in colour.

Do you want to learn the chemical properties of metals?

YOU CAN ALSO READ: PART -2- METALS AND NON -METALS

NCERT SCIENCE CLASS 10-2021- ACIDS BASES AND SALTS- NOTES-part-5- CHEMICALS FROM COMMON SALT

 NCERT SCIENCE CLASS 10- ACIDS BASES AND SALTS- NOTES-part-5- CHEMICALS FROM COMMON SALT

NCERT SCIENCE CLASS 10- ACIDS BASES AND SALTS- NOTES-part-5- CHEMICALS FROM COMMON SALT

In the previous parts of chapter acids, bases and salts, you have learnt the chemical properties of acids and bases. In this part you will be learning some of the important compounds formed from sodium chloride and its properties.

 

Sodium chloride (NaCl) is formed by the combination of sodium hydroxide(NaOH) and hydrochloric acid(HCl). Common salt is commonly used in the kitchen for cooking purposes. It is mainly found in sea water. You have studied it earlier as a neutral salt because it is the salt of a strong base and a strong acid. The seawater contains many salts dissolved in it and NaCl is one of them.

Common salt can be extracted just by storing the seawater in salt fields  so that water evaporates leaving behind the salts. Deposits of solid salt are also found in various places of earth.The salt obtained like this is called rock salt which is brown in colour due to the presence of impurities in it. It  can be purified to get common salt.

ROCK SALT

 

COMPOUNDS FROM COMMON SALT

Common salt is a raw material for making many chemical compounds. Some of them are sodium hydroxide, baking soda, washing soda and bleaching powder.

SODIUM HYDROXIDE

 When common salt is dissolved in water, its solution is called brine and when it is electrolyzed by passing the electric current, it dissociates into sodium ions and chlorine ions. Sodium ions are deposited at cathode and chloride ions are deposited at anode where it forms chlorine gas. So chlorine gas is liberated at anode and sodium ions that are liberated at cathode combine with water to form sodium hydroxide and hydrogen gas.

         2 NaCl + 2 H2O → 2NaOH + Cl2 + H2

So three substances are formed by the electrolysis of aqueous solution of NaCl. They are hydrogen gas, chlorine gas and NaOH.

Uses of H2, Cl2 and NaOH

All of them are very important raw materials for making so many useful things.

• Hydrogen gas is used as a fuel and it gives a large amount of energy on burning.
• It is also used for making  margarine for dehydrogenation of vegetable oils.
• Chlorine gas as you know it is used to disinfect water and also in the swimming pools for disinfecting water.
• For making poly vinyl chloride .
• To make chlorofluorocarbons used in refrigerators and also used to make pesticides.
• Hydrogen and chlorine will combine together and form HCl  gas. It is used for cleaning steel, for making cosmetics, medicines and ammonium chloride.
• NaOH is used for degreasing metals, for making soaps and detergent.
• It is also used for making paper and artificial fibers. 

• NaOH and Cl2 are used to make bleach and is used to make household bleach and for bleaching fabric.

BLEACHING POWDER 

 Another important compound is bleaching powder. Its formula is CaOCl2.  It is also called calcium oxychloride. It is formed by passing chlorine gas over Ca(OH)2.

Ca(OH)2 + Cl2 → CaOCl2 + H2O

• Bleaching powder is widely used for bleaching cotton and linen in the textile industry. 
• It is used in the paper industry also for bleaching wood pulp. 
•  In the laundry, it is used for bleaching washed clothes to remove any stain on them.  
• It is also used as an oxidizing agent in many chemical industries.
• It is used to disinfect drinking water to make it germ-free.

BAKING SODA

 The next compound which can be prepared from common salt is baking soda. Baking soda is commonly used in the kitchen for baking bread, baking cakes and for cooking. Baking soda is a general name and chemically it is called sodium hydrogen carbonate and its formula is NaHCO3.

 It is prepared by a reaction between NaCl, carbon dioxide, ammonia and water.

NaCl  + H2O  + CO2 + NH3 → NH4Cl + NaHCO3

 Sodium hydrogen carbonate and ammonium chloride are formed. On heating sodium hydrogen carbonate, it forms sodium carbonate and water. 

2 NaHCO3 →  Na2CO3 + H2O + CO2

You have already studied baking soda and its basic nature. How it is used to treat acidity in the stomach? It is also used for baking bread and cakes.

BAKING POWDER

BAKING BREAD

 Baking powder is a mixture of sodium hydrogen carbonate and tartaric acid. When baking soda is mixed with water, it liberates carbon dioxide gas which makes the dough rise and makes the bread and the cake spongy and fluffy. So it is widely used in baking.

NaHCO3 + H⁺ → CO2 + H2O + Sodium salt of acid

It is also used as an antacid to remove acidity in the stomach and it is also used for fire fighting in soda acid fire extinguishers. It liberates carbon dioxide gas by reacting with an acid which extinguishes the fire.

WASHING SODA

 The next compound which can be prepared from sodium chloride(NaCl) is washing soda(Na2CO3.10H2O). 

As we have discussed, sodium hydrogen carbonate(NaHCO3) is formed from NaCl, carbon dioxide and ammonia. On heating NaHCO3, it forms sodium carbonate(Na2CO3). This sodium carbonate is dissolved in water and is recrystallized. On recrystallization, it forms washing soda which is Na2CO3 .10 H2O. In the formula, there are 10 molecules of water present. These molecules of water are called water of crystallisation and they form a part of the crystal structure.

Na2CO3 + 10 H2O → Na2CO3.10H2O

•  Washing soda is used in various places like in the glass, soap and paper industries. 
• It is used in manufacturing sodium compounds like borax. 
•  It is used as a cleansing agent in homes.
•  It removes the permanent hardness of the water. It makes the permanent hard water to soft water.

WATER OF CRYSTALLIZATION

We will discuss some more compounds which have water of crystallization. Are the crystals of salts really dry? They are dry, but some crystals of salts of some compounds have water molecules that become a part of the crystal structure.

The water of crystallization is the number of water molecules attached to one formula unit of salt.

ACTIVITY

 Let us, first of all, perform an activity. Take a dry test tube and take copper sulphate(CuSO4.5H2O) crystals in it which are blue in colour. Hold it with the help of a holder and heat it over the flame of the bunsen burner. After some time it is found that the blue colour changes to white. It forms anhydrous copper sulphate(CuSO4). 

Anhydrous means the salt from which water molecules have been removed. 

The salt in which there is the water of crystallization in the crystal is called hydrated salt. Now on this white salt, if water drops of water are sprinkled, it again changes back to blue.

PLASTER OF PARIS

We have already studied Na2CO3. 10 H2O. There is another example- gypsum CaSO4 . 2 H2O. It has 2 molecules of water in the crystal. When gypsum is heated to about 373 Kelvin, it forms Plaster of Paris(POP). The plaster of Paris is calcium sulphate hemihydrate. So on heating gypsum, we get calcium sulphate hemihydrate.

CaSO4.2H2O → CaSO4.1/2H2O + 11/2 H2O

Now you will be surprised why it is half H2O.  Actually, one water molecule is shared by two calcium sulphate

molecules. We can also write it like this.

2CaSO4.H2O

Here 2 molecules of calcium sulphate share one molecule of water. 

As you all know, the Plaster of Paris is used by doctors to make the plaster over the fractured bones to cure them. Actually what happens when plaster of Paris is mixed with water. It forms gypsum again which is a hard mass. It is called setting the Plaster of Paris.

CaSO4.1/2H2O + 1 1/2H2O → CaSO4.2H2O

PLASTER

It is also used to make toys and statues which are used for decorating the houses and you must have heard about POP walls and the ceilings. So it is also used for decorating the walls and the ceilings of the houses.

POP STATUE

POP CEILING

In chapter acids, bases and salts, there are many activities involved. There were many application-level questions from these topics in the previous years' board exams. The formula of all important salts to be studied. More emphasis is to be given to the method of preparation of each salt and its uses.

YOU CAN ALSO READ: METALS AND NONMETALS PART 1 

NCERT CLASS 10-2021-SCIENCE-ACIDS,BASES AND SALTS- NOTES- PART 4- FAMILY OF SALTS

 

NCERT CLASS 10 SCIENCE-ACIDS,BASES AND SALTS- NOTES- PART 4- FAMILY OF SALTS

NCERT CLASS 10 SCIENCE-ACIDS,BASES AND SALTS- NOTES- PART 4- FAMILY OF SALTS

Now you will study some more about salts. As you already know that salt is formed by the combination of acid and base to form salt and water. So an activity can be performed.

 A list of salts is given to make a table. Write the formula of the various salts also. Identify from which acid or base it is formed. 

SALT	ACID	BASE
K2SO4	H2SO4	KOH
Na2SO4	H2SO4	NaOH
CaSO4	H2SO4	Ca(OH)2
MgSO4	H2SO4	Mg(OH)2
CuSO4	H2SO4	Cu(OH)2
Na2CO3	H2CO3	NaOH
NH4Cl	HCl	NH4OH
NaCl	HCl	NaOH
Mg(NO3)2	HNO3	Mg(OH)2

 

All of you can do this activity yourself simply. 

Write the names of the salts and rest you fill the table yourself. So it will make you perfect. You can learn the formula also without referring to the book.

 You make a table of the salts and make the salt solutions in water. Dissolve them and also find out which of the salts are soluble in water and which salts are not soluble in water.

So this activity can be performed in the lab and also you can test whether the salt solution is acidic or basic or neutral with the help of blue and red litmus paper.  Also you can find out the pH you using  the universal indicator paper.

  Salt of a strong acid and a strong base- neutral salts

Example 1-  NaCl is common salt. It is formed from HCl and NaOH.  NaOH is a strong acid and  HCl is also a strong acid. When you test it with blue litmus paper or red litmus paper, you will find that it is neutral.

 It neither changes the colour of blue litmus paper nor the colour of red litmus paper. It is neutral and also the pH is 7.

Example 2- KNO3 is formed from base KOH and acid HNO3. Both are strong. KOH is a strong base and HNO3 is a strong acid. And here also the salt is neutral as in the previous case.

So these are the salts of strong acid and strong base and they are called neutral salts ,which neither turn the colour of blue litmus paper or red litmus paper and pH is also 7.

  

Salt of a strong acid and a weak base – acidic salts

Example - aluminum chloride. It's formula is AlCl3. It is formed from a weak base aluminum hydroxide and a strong acid HCl. Now when it is tested with blue litmus paper, it turns the colour of blue litmus paper to red, showing thereby that the aluminium chloride salt solution is acidic in nature. So these are acidic salts.

 So acidic salts are formed by the combination of weak base and strong acid. pH value will be less than 7.

Zinc sulphate and copper sulphate are other examples of acidic salt.

Copper sulphate CuSO4 formed by weak base copper hydroxide and strong acid H2SO4.

 Salt of a strong base and a weak acid- basic salt

 Let us see the nature of sodium acetate? Its formula is a little bit complicated as you can see it (CH3COO)2Na. It is formed by the combination of  strong base NaOH and a weak acid acetic acid CH3COOH. 

When it is tested with red litmus paper, the colour of the red litmus paper changes to blue, showing thereby that the salt solution is basic in nature. pH value will be more than 7.

 So these are basic salts. There are some more examples of basic salts.

Sodium carbonate Na2CO3 formed by the combination of a strong base NaOH and a weak acid H2CO3 carbonic acid. It is also basic in nature.

Sodium hydrogen carbonate (baking soda) formula is NaHCO3 formed by the combination of a strong base NaOH and a weak acid H2CO3 ( carbonic acid). This is also basic in nature.

Family of sodium salts

 NaCl, CH3COONa, Na2CO3, NaHCO3

Sodium chloride ,sodium acetate ,sodium carbonate, sodium hydrogen carbonate. Sodium is common in families of sodium salts.

 Family of sulphate

Na2SO4, ZnSO4, K2SO4, MgSO4, CuSO4

Sulphate is common in Sodium sulphate , zinc sulphate, potassium sulphate, magnesium sulphate, copper sulphate.

Similarly sodium sulphate, sodium chloride, sodium nitrate, sodium carbonate are all sodium salts.

Carbonates- calcium carbonate, sodium carbonate, magnesium carbonate etc.

Hydrogen carbonates is a different family with members like sodium hydrogen carbonate, potassium hydrogen carbonate .

Sodium chloride, aluminum chloride or potassium chloride will form chloride family.

 So like this potassium nitrate. sodium nitrate will form a family of nitrates.

In the next portion we can learn about some important sodium salts and calcium salts.

NCERT class 10 2021- science- chapter 2- acids, bases and salts - pH and importance of pH in everyday life-notes-part-3

 ACIDS, BASES AND SALTS - pH and importance of pH in everyday life-notes-part-3

acids, bases and salts - pH and importance of pH in everyday life

HOW TO FIND OUT THE STRENGTH OF ACID OR BASE?

How do we find whether the particular acid is strong?
 Can we measure hydrogen ion concentration quantitatively?

Acids give hydrogen ions and bases give hydroxide ions. The hydrogen ion concentration can be measured with the help of a pH scale. P stands for Potenz in German, meaning power.

pH is inversely proportional to hydrogen ion concentration. So if hydrogen ion concentration is more, its pH will be less.

In a basic solution, hydroxide ion concentration will be more and in that case pH will be higher. 

pH scale

pH scale has been made from 0 to 14.

pH  - 0 -7 - acidic

pH  -     7 - neutral

pH  - 7 to14- basic

The pH of 0 to 7 indicates the acidic nature of the solution. If the pH of a particular solution is zero, it means it is strongly acidic and as pH increases the acidic nature decreases as hydrogen ion concentration decreases. 

pH will be 7 for distilled water. It means the solution is neutral.  

pH from 7 to 14 indicates the basic nature of the solution.

So on this scale, we can find out whether a particular solution is acidic or basic, strongly acidic or weakly acidic, concentrated solution or a dilute solution.

Universal indicator is a mixture of several indicators. Different acids at different hydrogen ion concentrations give different colours with universal indicators which can be then compared with standard pH colour charts.

The numbers on the chart indicate the pH values. By matching the colour, pH can be found.

If pH is zero it will be dark red, if pH is 4 it will be orange, if pH is 7 it will become green if pH is14 it will become violet.

We have discussed the pH of the various solutions. pH is a measure of hydrogen ion concentration. An acid gives hydrogen ions in a solution. More are the hydrogen ions present in the solution, less is the pH and strong is the acid. So pH is a measure of acidic strength of the solution.

An activity can be performed by taking various solutions in daily life and testing their pH and finding out whether these solutions are acidic or basic or neutral.

ACTIVITY

Saliva before a meal is taken and then it is tested with a universal indicator. The colour changes to green. pH is approximately 7.4 and as you know if the pH of the solution is above 7 it is slightly basic. Similarly, saliva after a meal is taken and its colour on the indicator is orange-yellow. The pH is 5. 8 and this is acidic.

You simply need to remember that if pH is below 7 it is acidic, if pH is 7 it is neutral and from 7 to 14 it is basic in nature. Here are the pH value and the colour change of few samples.

Lemon juice  - red - 2.5- acidic

Aerated drink - greenish-yellow -6 – acidic

Coffee -orange  – 5  -  acidic

Tomato juice –orange- 4.1 –acidic

Tap water-greenish- yellow-slightly acidic

Sodium hydroxide- violet- -14- strong base

HCl- dark red - 0 –strong acid

WHAT IS THE IMPORTANCE OF pH IN OUR EVERYDAY LIFE?

pH is very important in our everyday life. 

1. Plants and animals are pH-sensitive.

Our body works well at a pH range of 7 to 7.8.

Acid rain-  Acidic gases present in the air reacts with rainwater and forms acids. If it falls on plants and animals, it is quite harmful. If the pH of this rain is less than 5.6, it is very harmful to the plants and animals. Acid rain falling in the river is a threat to aquatic animals. pH is a very important factor for plants and animals.

2. pH of the soil

You can collect different samples of soil from different places and also note down what type of plant is growing there.

You can perform an activity. Take 2 grams of soil in a test tube and add about 5ml of water distilled water and shake it well and then filter it. The impurities or the solid particles will remain on the filter paper and the solution can be collected. That is called the filtrate.

 Test this filtrate with universal indicators and then compare it with the standard Universal indicator colour chart. Find out pH by the colour change and find out the pH of the soil collected from various places. If the pH is less than 7 it will be acidic, if pH is more than 7 it will be basic.

quick lime with soil

The plants will grow better at a pH 7. So if the soil is acidic in nature, then it can be neutralized by
adding quicklime (calcium oxide) or calcium hydroxide. If the soil is basic then it can be neutralized by an acid. Manure or compost is added to the soil for this purpose.

3.  pH in our digestive system-

acidity

When food is eaten, the stomach produces dilute HCl which helps in the digestion of the food. This dilute hydrochloric acid does not harm the lining of the stomach. But sometimes dilute HCl is secreted by the stomach in excess. It may be due to overeating or it may be due to indigestion.

Sometimes eating spicy food or mental stress can cause acidity. Then it will harm the stomach walls and it may cause ulcers and the burning sensation. The pain will be there initially, but if it is increased it may cause ulcers also.

So acidity is a serious problem and it must be removed. As discussed earlier the effect of an acid can be neutralized by taking either baking soda solution or by using milk of magnesia (that is a solution of magnesium hydroxide in water)which neutralizes the acid formed in the stomach. It gives relief from acidity.

 4.pH change in tooth decay

All of us know that tooth decay and it causes a lot of pain. In our mouth, the pH is generally a little bit above 7.Slightly basic it is. But when the food is eaten, some of the food gets stuck in the teeth and the bacteria which are present inside the mouth break down these food particles and produce acids. The pH value becomes lower than 7 due to the formation of the acid inside the mouth.

If the pH falls below 5.5, the tooth decay occurs at the hardest part of the tooth – ie, enamel (made up of calcium phosphate). Always brush your teeth after every meal and that is very much necessary. 

 

toothpaste

Toothpaste which we use is also basic in nature. So brushing the teeth not only will remove the food particles from the mouth. It will neutralize the acid formed in the mouth thereby preventing the tooth decay. 

5. Self-defence- Chemical warfare

Plants and animals defend themselves by chemical warfare by producing certain acids or bases and they protect themselves. How do they defend themselves?

honey bee

When honey bee sting, what do you feel? You feel very much irritated. You feel some pain because honey bee stings leaves acid on the skin due to which irritation and pain occurs and this acid which is left on the skin can be neutralized by baking soda solutions. It gives relief because baking soda will neutralize the acid left on the skin.

stinging nettle leaves

Also, there is a plant called nettle. It has very small hair on its leaves which causes stings. If by chance you happen to touch those leaves you will feel certain irritation because this produces an acid called methanoic acid. This irritation and pain can be removed by applying baking soda solution which will neutralize the effect of the acid methanoic acid.

Nature has provided dock plants which grow in the neighbourhood of these nettle plants and if you rub that area on which the nettle sting has occurred, it gives relief. So next time when you happen to visit someplace where nettle plants are growing. You can identify them and find that dock plants are also growing there.

dock plant

ORGANIC ACIDS

There are some naturally occurring acids which are present in plants as well as the animals. Naturally occurring acids are called organic acids. Vinegar is commonly used in the kitchen for cooking purposes. It contains acetic acid. Lemon or orange contains citric acid . Tamarind which is used for cooking purposes contains tartaric acid. Tomatoes also contain oxalic acid. Sour milk or curd contains lactic acid and ant or bee sting as well as the nettle sting contains methanoic acid. So these are all organic acids.

In the previous board exams, many questions were there from the topic related to pH. Application-level questions with pH values also can be asked from this topic.

Do you want to learn salts and some important compounds obtained from common salt? You can refer my next blog for that.

YOU MAY ALSO READ: PART 4 ACIDS,BASES AND SALTS

                                   : PART 5 ACIDS, BASES AND SALTS