MIXTURES Chemistry Module 1
Mackenzie King 3S2
Pure Substances, Elements & Compounds
Definitions: Pure Substance- A sample of matter that has definite chemical & physical properties. (EG. Iron, steel, water) Elements- A pure substance that cannot be separated into simpler substances by physical or chemical means. (EG. Carbon, Hydrogen) Compounds- A pure substance of two or more different elements joined by chemical bonds. (EG. Salt, H20)
FUN FACT! Compounds cannot be separated chemically.
Definition: A mixture is a combination of two or more pure substances that are not chemically combined. No chemical change takes place & a mixture can be physically separated. (EG. Salads, coffee)
Homogeneous and Heterogeneous mixtures
Homogeneous mixtures are also known as solutions. Its substances that are evenly distributed throughout the mixture. You cannot easily see the different parts of this mixture. (EG. Blood, coffee, salt water) A heterogeneous mixture- Substances that are not distributed evenly throughout the mixture. You can easily see the different parts. (EG. Oil & water, chicken noodle soup) The difference between the two mixtures above is that with the homogeneous mixture its substances are evenly distributed & it is harder to identify the different parts of it because it's not easily visible. But with the heterogeneous mixture it’s the exact opposite.
Physical & Chemical Changes
A physical change are changes affecting the form of a chemical substance but not it's chemical composition. Physical changes are used to separate mixtures into their component compounds but cannot usually be used to separate compounds into chemical elements or simpler compounds. A chemical change creates a new product. Chemical changes are changes affecting not only the physical but the chemical composition of a substance. The changes in Chemical change are irreversible and permanent. The difference between them is that basically physical changes affect the physical appearance of the substance and chemical changes affect the substance chemical composition.
Suspensions, Solutions & Colloids
Definitions: Suspensions- Suspension in science refers to a mixture where a solid particle does not dissolve in a liquid solution. These types of mixtures are referred to as heterogeneous. (EG. Oil shaken in water) Solutions- A solution consists of a solute and a solvent. The solute is the substance that is dissolved in the solvent. The amount of solute that can be dissolved in solvent is called its solubility. (EG. In a saline solution, salt is the solute dissolved in water as the solvent) Colloids- A mixture where one of the substances is split into very minute particles which are dispersed throughout a second substance . The minute particles are known as colloidal particles. (EG. Dust and smoke in the air)
Saturated Unsaturated Solute Solvent Dilute Supersaturated
Differences Suspensions Solutions Colloids Particle size Greater than a 1000nm 0.01 - 1mm 1nm- 1000nm Type of mixture Heterogeneous Homogeneous Heterogeneous Appearance Cloudy, heterogeneous Clear, transparent and homogeneous Cloudy but uniform and homogeneous Separation of components through filtration Can be separated by filtration Cannot be separated by filtration Cannot be separated by filtration Separation of components through leaving the mixture to stand for an amount of time. Particles settle out Do not separate on standings Do not separate on standings Tyndall Effect variable None -- light passes through, particles do not reflect light Light is dispersed by colloidal particles