Solutions

Concentration of Solutions

Concentration = # of fish volume (L) Concentration = V = 1000 mL n = 2 fish Concentration = 2 “fishar” V = 1000 mL n = 4 fish [ ] = 4 “fishar” V = 5000 mL n = 20 fish [ ] = 4 “fishar” 1 fish 1 (L) Concentration = 1 “fishar”

V = 1000 mL n = 2 moles Concentration = 2 molar V = 1000 mL n = 4 moles [ ] = 4 molar V = 5000 mL n = 20 moles [ ] = 4 molar Concentration = # of moles volume (L) V = 250 mL n = 8 moles [ ] = 32 molar

Concentration…a measure of solute-to-solvent ratio concentrated vs. dilute “lots of solute” “not much solute” “watery” Add water to dilute a solution; boil water off to concentrate it.

Making a Dilute Solution Timberlake, Chemistry 7 th Edition, page 344 initial solution remove sample diluted solution same number of moles of solute in a larger volume mix moles of solute

Concentration “The amount of solute in a solution” mol L M A. mass % = mass of solute mass of sol’n B. parts per million (ppm)  also, ppb and ppt – commonly used for minerals or contaminants in water supplies C. molarity (M) = moles of solute L of sol’n – used most often in this class D. molality (m) = moles of solute kg of solvent M = mol L % by mass – medicated creams % by volume – rubbing alcohol

Want to see what taking in a milligram per kilogram of your body weight amounts to? It’s the equivalent of 726 people, each weighing 150 pounds, sharing a chocolate bar (~50 grams). A part per million may be hard to comprehend or visualize. Want to see how much it is? A step in a journey of 568 miles. Or one minute in two years. Taking that further, a part per trillion is a million times smaller than that credit card on the football field, for example, or 6 feet out of a journey of six round trips to the sun (Editor's note: 95 million miles one way to the sun). It’s a credit card lying in the middle of a football field.