10th Class Chemistry Fundamentals

Matter and Energy

• Matter is anything that has mass and occupies space
• Examples of non-matter include light, heat, sound, and other forms of energy

Separation Techniques

• Distillation is the best technique for separating liquids with different boiling points
• Distillation works by separating liquids based on their boiling points, with the liquid having the lower boiling point vaporizing first
• If the boiling points are the same, distillation is not effective

Physical and Chemical Changes

• Physical changes:
  • NaCl dissolving in water (salt remains salt, just dissolved)
  • An apple being cut (apple is still apple, just in smaller pieces)
  • Heat changing H2O to steam (water changes state, but is still water)
  • Alcohol evaporating (alcohol changes state, but is still alcohol)
  • Ice melting (water changes state, but is still water)
• Chemical changes:
  • Ag tarnishing (silver reacts with sulfur to form silver sulfide)
  • Baking soda reacting to vinegar (new substances formed, gas released)
  • Fe rusting (iron reacts with oxygen to form iron oxide)

Physical and Chemical Properties

• Physical properties:
  • Color (e.g., blue)
  • Density
  • Solubility
  • Melting point
  • Luster
• Chemical properties:
  • Flammability
  • Reacting with acid
  • Supporting combustion

Classification of Substances

• Elements:
  • Gold (Au)
• Compounds:
  • Salt (NaCl)
  • Pure Water (H₂O)
• Solutions (homogeneous mixtures):
  • Salt Water
  • Steel (iron and carbon)
  • Gatorade
• Heterogeneous mixtures:
  • Sand
  • Soil
  • Italian salad dressing
  • Chocolate Chip Cookie
  • Fruit Pebbles cereal

Identifying Physical and Chemical Changes

• NaCl (salt) dissolves in water, remaining salt, but in a dissolved state, making it a physical change.
• Silver (Ag) tarnishes when it reacts with sulfur to form silver sulfide, a new substance, making it a chemical change.
• Cutting an apple into smaller pieces is a physical change, as the apple remains an apple, just in a different form.
• Heating water (H2O) to produce steam is a physical change, as the water changes state but remains water.
• Mixing baking soda with vinegar results in a chemical change, as new substances are formed and gas is released.
• Rusting of iron (Fe) occurs when it reacts with oxygen to form iron oxide, a new substance, making it a chemical change.
• Evaporation of alcohol is a physical change, as it changes state but remains alcohol.
• Melting of ice to form water is a physical change, as water changes state but remains water.

Test your understanding of basic chemistry concepts, including matter and energy, separation techniques, and physical and chemical properties.