States of matter

• Solids have strong forces of attraction between particles and are in a fixed arrangement
• Particles keep a definite shape and volume in solids, and they vibrate around their positions
• Liquids have weaker forces of attraction, and are randomly arranged
• Liquids have a definite volume but not a definite shape, and are constantly moving with random motion, with speed increasing with temperature
• Gases have very weak forces of attraction, and are free to move
• Gases don't have definite shape or volume, and move constantly with random motion
• Dissolving potassium manganate(VII) in water demonstrates that the diffusion in liquids is very slow because there are only small gaps between the liquid particles into which other particles diffuse.

  The random motion of particles cause the purple colour to eventually be evenly spread out throughout the water.

  Adding more water to the solution causes the potassium manganate(VII) particles to spread out further apart therefore the solutions becomes less purple. This is called dilution.
• What white solid is formed when ammonia gas and hydrogen chloride gas react?

  Ammonium chloride
• What is the chemical equation for the reaction between ammonia and hydrogen chloride?

  NH3(g) + HCl(g) → NH4Cl(s)
• How was ammonium chloride formed in the experiment described?

  • Ammonia solution soaked cotton wool pad
  • Hydrogen chloride solution soaked cotton wool pad
  • Pads placed in opposite ends of a dry glass tube
  • Reaction produces ammonium chloride
• Why does the white ring of ammonium chloride form closer to the hydrochloric acid end?

  Ammonia particles are lighter and travel faster
• How long does it take for the white ring of ammonium chloride to form, and why?

  About 5 minutes due to random particle movement
• What factors contribute to the time it takes for the ring to form in the experiment?

  Random movement and collisions with air particles
• What is the state of ammonium chloride formed in the reaction?

  Solid (s)
• What are the physical states of ammonia and hydrogen chloride in the reaction?

  Both are gases (g)
• How does the speed of ammonia particles compare to hydrogen chloride particles?

  Ammonia particles travel faster than hydrogen chloride
• What is the significance of particle collisions in the formation of ammonium chloride?

  They slow down the formation process
• A solution is a mixture of solvent and solute that doesn't separate out
• A solute is the substance that is dissolved
• A solvent is the liquid that dissolves the solvent
• A saturated solution is a solution where the maximum amount of solute has been dissolved, so no more solute can dissolve