Solutions and Solution Concentrations

 

Solutions and Solution Concentrations Solutions A solution can be defined as a homogeneous mixture of two or more substances. In a solution, there is the solute, the part or parts that are being dissolved, and the solvent, the part that is doing the dissolving. Solutions can be a liquid in a liquid, a solid in a liquid, or a solid in a solid. The following are types of solutions.    Compounds: Mixtures of different elements to create a single matter.    Alloys: Solid solutions of metals to make a new one such as bronze, which is copper and tin, or steel, which is iron and carbon, and may contain, tungsten, chromium, and manganese.    Amalgams: A specific type of alloy in which a metal is dissolved in mercury.    Emulsions: Mixtures of matter that readily separate such as water and oil. Concentration of Solutions—Percent Concentration Concentration is expressed as weight per weight, as in grams per grams; weight per volume, as in grams per liters; or volume per volume, as in milliliters per liter. Percent concentration is the expression of concentrations as parts per 100 parts. Therefore, most concentrations of this type are expressed as milligrams (mg) per 100 milliliters (mL), which can also be written as mg/100mL or mg/dL. A concentration expression of milliliters (mL) per 100 milliliters (mL) can be written as mL/100mL or mL/dl. Concentration of Solutions—Molar Concentration Molarity, or molar concentration, is a more sophisticated way to express concentrations than percent. One of the most important concepts in chemistry is the “mole.” A mole is 6.02 × 1023 molecules of something. This number, 6.02 × 1023, which is more than a trillion trillions, is known as Avogadro’s number. A one molar solution will contain 6.02 × 1023 representative molecules of a solute in a liter of solvent. Molar concentrations are written as mol/L. It is important to note that if one measured the atomic mass of any element in grams (g), he or she will have weighed out one mole or 6.02 × 1023 atoms of that element or compound.

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