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Is matter around us pure?

CBSE CHEMISTRY Class 9 IB DIPLOMA CHEMISTRY MYP 3 MYP 4 MYP 5 MYP CHEMISTRY

Is matter around us pure?

Q:IS matter around us pure? Answer:Matter around us has both pure and impure substance.

Pure Substance:

Pure substance has only one type of particles.

Example: Elements and Compounds

ELEMENTS AND COMPOUNDS

Elements: It is a pure substance which contains only one type of atoms.

Example: Hydrogen, oxygen, Iron, Mercury etc.

There are about 115 elements recognized so far.

about 85% elements are Metals, rest non-metals and semi-metals.

Metals: Such elements have either 1,2 or 3 electrons in the outer most shell.

Exqample; Sodium has 11 electrons so the configuration is 2,8,1 so it is a metal because it has only one electron in the last shell.

These elements show following properties;

Metals are malleable which means that Metals can be beaten into sheets. and they are ductile as well: Metals can be drawn into wires.

Metals are good conductor of heat and electricity.

They are sonorous: Metals produce sound on hitting by a solid.

The Metals have lusture: Metals have shiny surface.

Non- Metal: Such elements have either 4,5,6,7 or 8 electrons in the outer most shell. Noble gases are also non-metal but they are specifically inert and studied separately.

Example: chlorine has 17 electrons so configuration is 2,8,7. It is a non metal because it has 7 electrons in the last shell.

These elements show following properties;

Non-Metals are bad conductor of heat and electricity because these donot have free electrons.

Exception is Graphite( Allotrope of carbon)

Non-Metals are neither malleable and ductile nor lustrous.

Non-metals are colorful. Example Iodine is violet, Chlorine is greenish yellow, carbon is black or gray(graphite)

Metalloid or semimetal: Such elements possess the properties of metals and non metals. Example:boron, silicon, germanium etc

Impure Substance or Mixture

Impure substance has two or more than two types of substances. Example: Mixtures

The Mixture: The Mixture is the physical combination of two or more types of substances.

              Example: Air is a mixture of gases, dust particles and water vapour.

Types of Mixtures

Homogeneous Mixture:

Homo means equal, thus such mixture contains equal distribution of particles. We cannot see particles of such mixture by naked eyes. All solutions are Homogeneous mixtures.

Example : Acid solutions, Salt solution etc

What is a solution?

Solution is a combination of solute and solvent.

Solute: substance with smaller amount in a solution.

Solvent: substance with larger amount in a solution.

Example: If Sulphuric acid is dissolved in water, sulphuric acid is a solute and water is a solvent.

CBSE Class 9 Chemistry-IS MATTER AROUND US PURE?
Solution

What is concentration?

It is the amount(mass/volume) of a solute in a given amount(mass/volume) of a solution.
It can be expressed in many ways.

 Mass by mass percentage = (Mass of solute/ Mass of solution)x100

Question: If 49 grams of Sulphuric acid are dissolved in 100 grams of a solutions, calculate the concentration of this solution?

Thus using the above formula,

Mass by mass percentage = (49 g/100g)x100

= 49%

Mass by volume percentage =(Mass of solute/ Volume of solution)x100

Question: If 50 grams of glucose are dissolved in 100 ml solution, calculate the concentration of the solution.

Thus Mass by volume percentage =(50g/ 100)x100

=50%

Volume by volume percentage =(Volume of solute/ Volume of solution)x100

If 20 ml of pure HCl acid are dissolved in 50 ml solution, calculate the concentration of the solution.

Thus Volume by volume percentage =(20 ml/ 50ml)x100

= 40%

Heterogeneous Mixture:

Hetero means unequal, such mixture contain unequal distribution of particles and we can see the particles either by naked eyes or microscope.

Example: colloid and suspension

Thus by now you must have learned -IS MATTER AROUND US PURE?

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