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States of Matter - Properties of Solids, Liquids, and Gases

Grade 6Cambridge (IGCSE)

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

🔑Concepts

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Matter is made of tiny particles (atoms or molecules). The kinetic theory of matter states that these particles are in constant motion.

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In a solidsolid, particles are packed closely together in a regular arrangement (a latticelattice). They vibrate about fixed positions but do not move from place to place.

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In a liquidliquid, particles are close together but arranged randomly. They have enough energy to slide past each other, which allows liquids to flow and take the shape of their container.

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In a gasgas, particles are very far apart and move rapidly and randomly in all directions. Gases can be compressed because of the large emptyspacesempty spaces between particles.

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Phase changes occur with the addition or removal of energy: meltingmelting (solid to liquid), freezingfreezing (liquid to solid), evaporation/boilingevaporation/boiling (liquid to gas), and condensationcondensation (gas to liquid).

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Density is a measure of how much mass is contained in a given volume: ρ=mV\rho = \frac{m}{V}. Solids generally have the highest density, while gases have the lowest.

📐Formulae

ρ=mV\rho = \frac{m}{V}

Vrectangular prism=l×w×hV_{rectangular\ prism} = l \times w \times h

Total Energy=Kinetic Energy+Potential Energy\text{Total Energy} = \text{Kinetic Energy} + \text{Potential Energy}

💡Examples

Problem 1:

A sample of unknown liquid has a mass of 200g200g and occupies a volume of 250cm3250cm^3. Calculate the density of the liquid.

Solution:

ρ=200g250cm3=0.8g/cm3\rho = \frac{200g}{250cm^3} = 0.8g/cm^3

Explanation:

The density is calculated by dividing the mass (mm) by the volume (VV). In this case, 200200 divided by 250250 gives 0.8g/cm30.8g/cm^3.

Problem 2:

Compare the compressibility of H2O(s)H_2O(s) (ice) and H2O(g)H_2O(g) (steam).

Solution:

H2O(g)H_2O(g) is highly compressible, whereas H2O(s)H_2O(s) is virtually incompressible.

Explanation:

In H2O(g)H_2O(g), the water molecules are far apart with significant space between them, allowing them to be pushed closer. In H2O(s)H_2O(s), the molecules are already in a fixed, close-packed structure with no room to move closer.

Problem 3:

Identify the state of matter where particles have the highest kinetic energy.

Solution:

The gasgas state.

Explanation:

Particles in a gas move at high speeds (vv) in random directions, meaning they possess the most kinetic energy (Ek=12mv2E_k = \frac{1}{2}mv^2) compared to particles in solids or liquids at the same temperature.