krit.club logo

Matter - States of Matter

Grade 6ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

•

Matter is defined as anything that occupies space, has mass, and can be perceived by our senses. It is composed of tiny particles called atoms or molecules.

•

The Kinetic Molecular Theory of matter states that particles are in continuous random motion and possess kinetic energy.

•

Intermolecular Space (SinterS_{inter}): The empty space existing between the molecules of a substance. It is minimum in solids and maximum in gases.

•

Intermolecular Force of Attraction (FinterF_{inter}): The force with which molecules attract each other. It is strongest in solids and weakest in gases.

•

Solids: Have a definite shape and a definite volume. Molecules are closely packed with negligible SinterS_{inter}.

•

Liquids: Have a definite volume but no definite shape (they take the shape of the container). Molecules are less closely packed compared to solids.

•

Gases: Have neither a definite shape nor a definite volume. They exhibit maximum fluidity and are highly compressible as SinterS_{inter} is very large.

•

Change of State: The process by which matter changes from one physical state to another by absorbing or releasing heat energy, such as melting (Solid to Liquid) or sublimation (Solid to Gas).

•

Water exists in three states: Ice (Solid), Water (H2OH_{2}O Liquid), and Water Vapor (H2OH_{2}O Gas).

📐Formulae

Density(d)=Mass(m)Volume(V)Density (d) = \frac{Mass (m)}{Volume (V)}

Volume of a Cube=l3Volume\ of\ a\ Cube = l^3

1 g/cm3=1000 kg/m31\ g/cm^3 = 1000\ kg/m^3

Volumetotal=Volumefinal−VolumeinitialVolume_{total} = Volume_{final} - Volume_{initial}

💡Examples

Problem 1:

A solid block of iron has a mass of 780 g780\ g and occupies a volume of 100 cm3100\ cm^3. Calculate its density in g/cm3g/cm^3.

Solution:

Density=780 g100 cm3=7.8 g/cm3Density = \frac{780\ g}{100\ cm^3} = 7.8\ g/cm^3

Explanation:

Density is the ratio of mass to volume. By dividing the given mass (780 g780\ g) by the volume (100 cm3100\ cm^3), we find the density of iron.

Problem 2:

Why does a gas fill the entire space of the vessel it is placed in?

Solution:

In gases, the Intermolecular Force (FinterF_{inter}) is almost negligible and the Intermolecular Space (SinterS_{inter}) is very large.

Explanation:

Because the particles have high kinetic energy and weak attractive forces, they move freely in all directions to occupy all available space.

Problem 3:

Identify the process when Naphthalene balls disappear over time without leaving any residue.

Solution:

Sublimation

Explanation:

Sublimation is the process where a solid directly converts into a gas upon heating (or at room temperature) without passing through the liquid state.