Pure Substances & Mixtures Quiz #1 – Wednesday March 5
A. The Particle Theory:
1. Matter (stuff) is made up of tiny particles (molecules) with spaces between them
2. Particles are always moving; the more energy they have the faster they move
3. Particles are attracted to one another…greater attraction in solids than in gases (they are closer together)
B. PURE SUBSTANCES: have only one kind of particle throughout. (ex. Diamonds)
C. MIXTURE: contains two or more pure substances. (ex. pop ; coke, pepsi, bread; mixture of yeast, flour, sugar, water, air, and other chemicals)
D. Two sub-categories of mixtures:
1. HETEROGENEOUS MIXTURE: means “different kinds”. Think of granola, if you were to take spoon-fuls of it, each spoonful would be different…you might get a raison, chocolate chip, nut, etc. Two or more substances can be seen and felt. Also known as a ‘mechanical mixture’.
2. HOMOGENEOUS MIXTURE: means “same kind”. ex. a steel bar, no matter where you cut it it looks the same, but it’s made up of a bunch of things. Also known as a ‘solution’. In a solution, one substance has mixed or DISSOLVED into another
- The substance that dissolves = solute
- The substance that does the dissolving = solvent.
Koolaid crystals + Water….which is the solute and which is the solvent?
The crystals are the solute and the water is the solvent.
E. SATURATED OR UNSATURATED? Have you ever made a drink by dissolving flavour crystals in water and found that it tasted ‘watery’ because you didn’t add enough crystals? Why does this occur? Because you didn’t have the right CONCENTRATION of SOLUTE in the SOLVENT.
- CONCENTRATION = the amount of solute dissolved in an amount of solvent or solution
- DILUTE SOLUTIONS = low concentration of solute
- CONCENTRATED SOLUTIONS = high concentration of solute Since both dilute and concentrated solutions still contain unfilled spaces between the particles, they are both UNSATURATED SOLUTIONS. SATURATED SOLUTIONS are where all the spaces are filled between the particles.
F. The SOLUBILITY of a solute is the exact amount of solute required to form a saturated solution in a particular solvent at a certain temperature.
