Chemistry

• What is an element?

  A substance made up of 1 atom
• What is a mixture?

  A substance made by mixing other substances
• What is a compound?

  A substance made from 2 or more elements
• What is a suspension?

  A mixture where solid particles do not dissolve
• What does it mean if a substance is insoluble?

  It does not dissolve.
• What is the process of filtration used for?

  • To separate an insoluble solid from a liquid
  • Uses filter paper with tiny holes
  • Solid is called residue, liquid is filtrate
• What is the residue in filtration?

  The solid trapped in the filter paper
• What is the filtrate in filtration?

  The liquid that passes through the filter paper
• What happens when flour is mixed with water?

  It forms a suspension
• What is evaporation used for?

  To separate a soluble solid from a liquid
• What is a solute?

  The solid that dissolves in a solvent
• What is a solvent?

  The liquid that dissolves the solute
• What happens to salt when it dissolves in water?

  It becomes part of a solution
• What is the chemical name for ordinary salt?

  Sodium chloride
• What are the steps to obtain pure salt from rock salt?

  1. Crush rock salt using a pestle and mortar
  2. Filter the mixture after adding water
  3. Evaporate the liquid to obtain salt
• What is chromatography used for?

  • To separate components of a mixture
  • Based on different solubility in a solvent
  • Used in crime labs for identification
• What does chromatography separate?

  Components that dissolve in the same solvent
• What happens to different components in chromatography?

  They travel different distances based on solubility
• What is an exothermic reaction?

  A reaction that gives out heat
• What is an endothermic reaction?

  A reaction that absorbs heat
• What are reversible and irreversible changes?

  • Reversible: Changes that can be undone (e.g., melting ice)
  • Irreversible: Changes that cannot be undone (e.g., cooking an egg)
• What is the definition of a chemical change?

  A change that alters the substance's chemical composition
• What is the significance of temperature change in chemical reactions?

  It indicates whether the reaction is exothermic or endothermic
• What happens to a material when it is heated?

  Its temperature goes up
• What can heating a material cause it to change?

  Color, size, shape, or state
• What are temporary changes when a material is heated?

  Changes that reverse when cooled
• What are irreversible changes when a material is heated?

  Changes that cannot be reversed on cooling
• What is an exothermic reaction?

  Heat is given out to surroundings
• What is an endothermic reaction?

  Heat is taken in from surroundings
• What happens to temperature in an exothermic reaction?

  It increases
• What happens to temperature in an endothermic reaction?

  It decreases
• What is rust?

  Red-brown substance from iron exposure
• What is the chemical name for rust?

  Hydrated iron (III) oxide
• What is the reaction that forms rust?

  Iron + oxygen + water → rust
• What is one method to prevent rusting?

  Store in low moisture area
• How does applying oil prevent rusting?

  It inhibits moisture from reaching iron
• What is an indicator?

  A solution that changes color in acids or alkalis
• What does a universal indicator do?

  Shows strength of acids or alkalis
• What is the pH of a neutral solution?

  7
• What is the process of neutralization?

  Adding acid to an alkali to make it neutral