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Solutions and Solubility
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Solution - What is it? A solution is a mixture of two or more kinds of molecules, atoms, or ions (or chemical compounds) that is homogeneous or appears to be all one thing.
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What are solutions made of?
Solute Solvent The substance being dissolved The substance doing the dissolving
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Solvent Solution Solute
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Identify the Solute/Solvent
Instant coffee dissolved in hot water. Sugar is also added to the solution. Antifreeze consists of methanol dissolved in water. Blue colouring is also added as a safety precaution. 3. Carbonated drinks (soft drinks) consist of a flavoured liquid containing dissolved carbon dioxide gas. 4. Water, oil and salt are mixed together.
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Weak tea Strong tea Pure substances, such as pure water, have a fixed composition. You cannot change the ratio of hydrogen to oxygen in water. Solutions, on the other hand, have variable composition, which means that different ratios of solvent to solute are possible.
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When a solvent dissolves a solute, no chemical reaction occurs
When a solvent dissolves a solute, no chemical reaction occurs. The solvent and the solute can be separated using physical measures, such as boiling or melting. A solution can be a gas, a liquid, or a solid. Various combinations of solute/solvent states are possible. Air is a mixture of nitrogen, oxygen, argon, and carbon dioxide gases. A gas can be dissolved in a liquid and a solid can be dissolved in another solid.
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Classification of Solutions * are most common to chemistry
Solute Solvent Example Gas Air (oxygen in nitrogen) *Gas Liquid Soft drink (carbon dioxide in water) Solid Ice (oxygen in ice) Humid air (water in air) *Liquid Antifreeze (methanol in water) Tooth fillings (mercury in silver) *Solid Syrup (sugar in water) Alloys (bronze is tin in copper)
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Some special terms for solids dissolved in liquids
Insoluble- a solid that does not dissolve in a given liquid Soluble- a solid that dissolves in a given liquid
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Some special terms for liquids dissolved in liquids
Immiscible- two liquids that do not dissolve in each other Have you heard the old expression "Oil and water do not mix?" This is an example of two immiscible liquids.
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Some special terms for liquids dissolved in liquids
Miscible liquids are those that can mix with each other. Have you ever made chocolate milk by mixing milk and liquid chocolate syrup? The two liquids mixed well and became a single solution -- and a tasty one, too! That's because they were miscible with each other, or mixed well.
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Aqueous solutions (aq)
Water is known as the universal solvent The polar nature of the water molecule enables it to dissolve many ionic and covalent compounds.
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Compounds with strong ionic bonds are hard to pull apart.
*** Not all ionic compounds are soluble in water. The strength of the ionic bonds within the lattice determine its solubility in water.*** Compounds with strong ionic bonds are hard to pull apart. The water molecules will only be weakly attracted. The compound is insoluble. Compounds with weak ionic bonds are easy to pull apart. The water molecules are strongly attracted. The compound is very soluble. When ions are surrounded by water molecules they become hydrated.
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Solubility The mass of a substance that will dissolve in a given volume of solvent at a specific temperature is referred to as solubility. If there is a large % of solute, it is said to be concentrated If there is a low % of solute it is dilute (fewer solute particles per volume of solvent) Dissolution is the rate at which a substance dissolves
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Types of Solutions Unsaturated- still able to dissolve more solute
The crystals of solute added will continue to disappear.
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Saturated- maximum amount of solute that will dissolve
Nothing will occur with the addition of more solute
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Supersaturated- past saturation…(by heating) crystals may and usually come out of solution.
The addition of more solute causes the precipitation of the solute to the saturation point.
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