Molarity & Dilutions
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The molarity equation. Be sure the solute is in moles, not grams; you may have to convert. The volume of the solution must be in liters for the equation.
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The dilution equation. Initial concentration (molarity) times initial volume is equal to the final concentration times final volume. They are inversely related.
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| Molarity Video Guide |
Solubility
Mr. Lee says: "Like dissolves like" is a phrase that means polar substances (like water) are good are dissolving other polar substances (like alcohol) or ionic compounds (like NaCl). This relates to intermolecular forces that exist between molecules.
Other examples of polar/ionic substances mixed into polar solvents:
- Ammonia in water
- Potassium iodide in water
- Dichloromethane in alcohol
Water (polar) and oil (non-polar) do NOT mix because they are not alike in terms of polarity.
Other examples of polar/ionic substances mixed into polar solvents:
- Ammonia in water
- Potassium iodide in water
- Dichloromethane in alcohol
Water (polar) and oil (non-polar) do NOT mix because they are not alike in terms of polarity.
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When two aqueous solutions are mixed, and a reaction occurs that generates a solid (often times a double-replacement reaction), the resulting solid that often "falls" is called a precipitate.
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In this example (which is not the same as the animated picture), two aqueous solutions are mixed and a DR reaction occurs. One of the products of the reaction (barium sulfate) is not soluble, and thus precipitates out as a solid.
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Acids and Bases
In the general high school chemistry curriculum, only strong acids and bases (with ~100% dissociation) are considered for calculations.
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KHAN ACADEMY ARTICLE: https://www.khanacademy.org/science/chemistry/acids-and-bases-topic/acids-and-bases/a/ph-poh-and-the-ph-scale
Calculating pH, pOH, [H+], [OH-] (Intro)
Acid-Base Neutralization
When you mix an acid and a base, they neutralize each other and two products are created: One is a salt (ionic compound) and the other is water.
Example #1: HCl + NaOH --> NaCl (the salt) + HOH (water)
Example #2: HBr + KOH --> KBr (the salt) + HOH (water)
When you mix an acid and a base, they neutralize each other and two products are created: One is a salt (ionic compound) and the other is water.
Example #1: HCl + NaOH --> NaCl (the salt) + HOH (water)
Example #2: HBr + KOH --> KBr (the salt) + HOH (water)