2.1 Physical Properties - module 1 - CHEM

What is matter?

Matter is anything that has mass and occupies space.

What are the three main states of matter?

Solid (fixed shape & volume), Liquid (fixed volume, no fixed shape), Gas (no fixed shape or volume).

What are pure substances?

Pure substances have a fixed composition and cannot be separated by physical methods.

What are the types of pure substances?

Elements (one type of atom, e.g., Oxygen, Hydrogen) and Compounds (chemically combined elements, e.g., Water).

What are mixtures?

Mixtures are physically combined substances that can be separated using physical properties.

What distinguishes homogeneous mixtures?

Homogeneous mixtures have uniform composition throughout (e.g., saltwater).

What distinguishes heterogeneous mixtures?

Heterogeneous mixtures have non-uniform composition where different parts can be seen (e.g., fruit cake).

What is the definition of physical properties?

Physical properties are characteristics that can be observed or measured without changing the substance into a new one.

What is the definition of chemical properties?

Chemical properties describe how a substance changes into a different substance during a chemical reaction.

What is a physical change?

A physical change occurs when the chemical composition of a substance remains the same.

What is a chemical change?

A chemical change occurs when the chemical composition changes, forming new substances.

What are some examples of physical changes?

Melting ice (solid water to liquid water) is an example of a physical change.

What are some examples of chemical changes?

Examples of chemical changes include combustion, rusting, and decomposition.

How do boiling points relate to mixtures?

Boiling points help separate liquids; pure substances have a sharp boiling point, while mixtures boil over a range.

What is distillation?

Distillation is a method used to separate liquids based on boiling point differences.

What is chromatography?

Chromatography is a technique used to separate dissolved substances based on their affinity to the solvent and stationary phase.

What is dilution and when is it useful?

Dilution is the process of reducing the concentration of a substance in a solution, useful in preparation for reactions and analyses.

What are the key differences between physical and chemical properties?

Physical properties do not result in new substances being formed; chemical properties do involve a change into new substances.

What is a homogeneous substance?

A homogeneous substance has a uniform composition throughout, meaning all parts are the same.

What is a heterogeneous substance?

A heterogeneous substance has a non-uniform composition where different parts can be seen and have different properties.

What is filtration?

Filtration is a method of separation used to separate an insoluble solid from a liquid based on particle size.

What is evaporation?

Evaporation is the process where a liquid turns into vapor, used to separate dissolved solids from a solution.

What is crystallization?

Crystallization is a process where a dissolved substance forms solid crystals when the solution cools, used to separate solid from liquid.

What is simple distillation?

Simple distillation is a technique used to separate liquids with very different boiling points by heating the mixture to vaporize the component with the lower boiling point.

What is fractional distillation?

… is used to separate liquids with close boiling points through repeated condensation in a fractionating column.

What is chromatography used for?

… is used to separate and analyze components dissolved in a solution based on their movement through a medium.

What is decantation?

Decantation is a separation technique where the liquid is poured off from a solid or another liquid, based on differences in density.

What is centrifugation?

Centrifugation is a process that separates components based on density by spinning the mixture rapidly.

What are the physical properties used for identification?

Physical properties such as melting point, boiling point, and density help identify pure substances and their purity.

What effect do impurities have on boiling point?

Impurities in a substance typically lower its boiling point or result in a boiling point range.

What defines a volatile substance?

A volatile substance easily turns into vapor, having a low boiling point, such as ethanol.