Mixing Particles

• Substances must move into and out of cells for an organism to function.
• Three processes contribute to this movement: diffusion, osmosis and active transport.
• If a crystal of a coloured chemical, such as potassium manganate (VII), is placed in water, the particles spread out and mix with the water particles.
• The potassium manganate (VII) is the solute.
• The water is the solvent.
• The potassium manganate (VII) has dissolved.
• When a substance breaks up and mixes completely with a solvent to produce a solution, the resulting mixture is the solution.
• The particles have moved from a region of high concentration to a low concentration in the water.
• The concentration of a solution tells us how much of a substance is dissolved in water.
• The higher the concentration, the more particles of the substance are present in the crystal to a low concentration in the water.
• The difference in the concentration of a chemical across a membrane is called a concentration gradient.
• Particles will move down a concentration gradient, from a high concentration to a low concentration.
• As well as diffusion occurring between different regions, it also occurs across membranes, between the outside and inside of cells.
• The rate of diffusion can be affected by a number of factors: the concentration gradient.