2. States of Matter & Changes of State

Question 1

Solid, Liquid, Gas

Answer 1

• Solid: Particles are packed tightly together with a regular pattern. Fixed shape and volume
• Particles in liquid are close together without a regular pattern. Particles are able to pass one another. Liquid has a fixed volume but indefinite shape, takes shape of container
• Gas: Particles are separated without a regular pattern, takes shape of container and fills the space of the container. Indefinite volume and shape.

Question 2

Changes of State

Answer 2

• The change of solid to liquid is known as melting.
• The change of liquid to gas is known as vaporization.
• The change of gas to solid is known as deposition.
• The change of solid to gas is known as sublimation.
• The change of liquid to solid is known as freezing.
• The change of gas to liquid is known as condensation.

Question 3

Vaporation v Evaporation

Answer 3

Question 4

Brownian Motion

Answer 4

Brownian motion is the random motion of particles suspended in a fluid (a liquid or a gas) resulting from their collision with the fast-moving atoms or molecules in the gas or liquid.

Question 5

Kinetic Molecular Theory

Answer 5

• Matter is composed of tiny particles that are always in motion. This theory helps explain observable properties and behaviors of solids, liquids, and gases.
• Gases consist of far apart particles in constant rapid motion, the average kinetic energy of gas particles is dependent on the temperature of the gas

Question 6

Pure Substances

Answer 6

• Pure substances are substances that are made up of only one kind of atom or molecule and have a fixed or constant structure; mostly homogeneous in nature
• It cannot be broken down or separated into new products.
• Pure substances have fixed boiling and melting points.
• Gold, copper, oxygen, chlorine, diamond, etc. Compounds such as water, salt or crystals, baking soda amongst others are also grouped as pure substances.

Question 7

Impure Substances

Answer 7

• It can be separated using different separation methods.
• An impure consists of different kinds of elements combined physically and not chemically. Impure substances are also called mixtures. Mixtures are further divided into homogenous or heterogeneous mixture.
• A homogeneous mixture is fully mixed with an even concentration
• A heterogenous mixture varies from spot to spot, for example, a mixture of sand and sugar in water will not be evenly mixed.

Question 8

Pure substance and impurities on melting and boiling point

Answer 8

• Pure substances melt at a fixed temperature
• Impure substance melt over a greater range, the melting point is dropped and the boiling point is increased. The change of state occurs over a wider range

Question 9

Pressure Changes

Answer 9

Pressure changes alter the melting point and boiling point of a substance. Increasing the pressure will decrease the melting point and increase the boiling point as more energy is required to boil. Decreasing pressure will increase the melting point and decrease boiling point.