Elements, Compounds, and Mixtures Quiz

Elements, Compounds, and Mixtures

• Matter occupies space and has mass
• Matter exists in two forms: pure substances and mixtures
• Pure substances are either elements or compounds
• Compounds are pure substances with a fixed composition and properties
• Mixtures are combinations of two or more pure substances
• Mixtures retain individual properties of components
• Components in mixtures are not chemically combined
• Mixtures can have components in any proportion

Pure Substances

• Pure substances have definite composition
• Examples include copper, salt, and sugar

Mixtures

• Mixtures are a combination of two or more substances (elements or compounds)
• Components retain individual properties
• Mixtures do not have a fixed composition
• Components can be separated by physical means
• Mixtures can be homogeneous or heterogeneous

Types of Mixtures

• Homogeneous Mixtures: Components are evenly distributed and cannot be distinguished visually
  • Examples include salt solutions, alloys (like brass), air
• Heterogeneous Mixtures: Components are not evenly distributed and can be visually distinguished
  • Examples include sand and water, chalk in water, dal and rice mixtures

Separation Techniques

• Sieving: Separates mixtures based on particle size
• Handpicking: Separates components by hand
• Sedimentation and Decantation: Separates mixtures where one component settles at the bottom
• Filtration: Separates mixtures where one component is a solid and the other is a liquid using a filter medium
• Evaporation: Separates a solid dissolved in a liquid by heating to evaporate the liquid
• Magnetic Separation: Separates mixtures using magnetism
• Winnowing: Separates lighter components from heavier ones by blowing air

Additional separation methods

• Centrifugation: Separates components based on density differences by spinning a mixture rapidly
• Distillation: Separates miscible liquids by their different boiling points
• Fractional Distillation: Separates mixtures of miscible liquids with close boiling points, using a fractionating column
• Sublimation: Separates substances that can change directly from solid to gas or vice versa (and vice versa)
• Froth Floatation: Separates ores from gangue using bubbles and surface tension