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Understanding Solutions. Chapter 7 Section1. Solutions. A solution is a homogenous mixture where the components of the mixture are evenly mixed. Looks uniform: color, density, texture. . . In a solution, one substance is dissolved into another substance:
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Understanding Solutions Chapter 7 Section1
Solutions • A solution is a homogenous mixture where the components of the mixture are evenly mixed. • Looks uniform: color, density, texture. . . • In a solution, one substance is dissolved into another substance: • Solute: the substance that is dissolved (smaller amount) • Solvent: the substance that is doing the dissolving (larger amount) • Salt Water • Carbonated Water
Dissolving The movement of molecules causes the solute to break apart and mix evenly throughout the solvent. – physical change • Liquids and gases dissolve easily. • Solid alloy solutions must be melted for dissolving to occur. • A liquid dissolves a solid at the surface of a solid. • Since water is a polar molecule, it works well as a solvent. This is why it’s called:
Can we reverse dissolving? • Supposed you dissolve a teaspoon of salt into a glass of water. Is it possible to recover the salt from the water?
Common Solutions • Look at each of these common solutions. • What is the solute? What is the solvent? • How is each one of these solutions formed?
Colloids • A colloid is a mixture that contains small, un-dissolved particles that do not settle out. • Small enough to not be seen • Large enough to “scatter light” or give a creamy or opaque texture • Examples: Milk, Gelatin, Mayo, Shaving Cream, Whipped Cream. . .
Is Fog/Mist a Solution or Colloid? • What are the two things being mixed? • Are they chemically combined? Or just mixed?
Suspensions • A suspension is a mixture in which particles can be seen and easily separated by settling or filtration. • No uniform properties • Visible particles • Examples: Heterogeneous Mixture, Snow Globe, Mud, Oil & Water
Ionic and Molecular Compounds • Salt Water – Ionic Compound mixes with Water • Positive and Negative Ions are attracted to the polar water molecules • Conducts electricity • Salt Water Dissolving Link on Moodle! • Sugar Water – Molecular Compound mixes with Water • Polar water molecules attract the sugar molecules and force them apart in the solution, spreading the solute throughout the solvent. • Doesn’t conduct electricity
Effects of Solutes on Solvents • Lower Freezing Points • Example: Salt Water (again!) • Pure Water Freezes at _______ ˚F / ________˚C • Salt freezes at a higher/lower temperature • So which freezes first: ocean or lake? • Higher Boiling Points • Example: Coolant • Pure Water Boils at _______ ˚F / ________˚C • Antifreeze boils at a higher/lower temperature • So which is safer for your car: water or coolant?
Check your knowledge! • Identify each Mixture: • Correctly match the vocabulary words below:
