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Matter and Materials - States of Matter (Solid, Liquid, Gas)

Grade 5ICSE

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

🔑Concepts

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Matter is anything that has mass and occupies space. It is made up of tiny particles called molecules.

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In Solids, molecules are very closely packed with strong intermolecular forces. They have a definite shape and a definite volume.

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In Liquids, molecules are less closely packed compared to solids. They have a definite volume but no definite shape, taking the shape of the container they are in.

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In Gases, molecules are far apart with very weak intermolecular forces. They have neither a definite shape nor a definite volume.

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Change of State: Matter can change from one state to another by heating or cooling. For example, ice (H2OH_2O in solid form) melts to become water (H2OH_2O in liquid form).

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A Solute is a substance that dissolves (e.g., sugar), a Solvent is the medium it dissolves in (e.g., water), and a Solution is the resulting mixture.

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Miscible liquids are those that mix completely with each other (e.g., milk and water), while Immiscible liquids do not mix (e.g., oil and water).

📐Formulae

Solute+Solvent=Solution\text{Solute} + \text{Solvent} = \text{Solution}

Density=MassVolume\text{Density} = \frac{\text{Mass}}{\text{Volume}}

Ice (Solid)→HeatingWater (Liquid)\text{Ice (Solid)} \xrightarrow{\text{Heating}} \text{Water (Liquid)}

Water (Liquid)→HeatingSteam (Gas)\text{Water (Liquid)} \xrightarrow{\text{Heating}} \text{Steam (Gas)}

💡Examples

Problem 1:

Explain what happens to the molecules of water (H2OH_2O) when it is heated from 0∘C0^\circ C to 100∘C100^\circ C.

Solution:

The molecules gain kinetic energy and start moving faster, eventually overcoming the intermolecular forces of attraction to turn into steam.

Explanation:

At 0∘C0^\circ C, water is typically ice (solid). Heating causes melting to liquid water. Continued heating to 100∘C100^\circ C leads to boiling/evaporation, where molecules move far apart to become a gas (water vapor).

Problem 2:

If 2020 grams of salt (NaClNaCl) is dissolved in 100100 grams of water (H2OH_2O), what is the mass of the resulting solution?

Solution:

20 g+100 g=120 g20\text{ g} + 100\text{ g} = 120\text{ g}

Explanation:

According to the principle of conservation of mass, the mass of the solution is the sum of the mass of the solute and the mass of the solvent.

Problem 3:

Why can a gas be compressed easily while a solid cannot?

Solution:

Gases have large intermolecular spaces between their molecules, whereas solids have almost no space between molecules.

Explanation:

Applying pressure to a gas pushes the molecules closer together (VV decreases). In solids, the molecules are already touching, so they cannot be pushed closer.