Solution ChemistrySolution Chemistry
  • Tap water: Variable chemistry and purity
  • Laboratory grade water: Reverse osmosis or distillation, Rinsing glassware, media preparation
  • Reagent grade water: Filtration, deionization, and carbon adsorption
  • Other specialized types: (dd, microfiltered, electrically deionized, etc)
  • Solution: A mixture in which individual molecules or ions are dispersed in a liquid.
  • Solvent: The liquid that makes up the majority of the solution. e.g., water (aqueous solution).
  • Solute: The minority component of the solution. Often a solid before mixing.

These are amount of solute per volume of SOLUTION.

  • Weight-per-volume (e.g., mg/L)
  • Percent (parts per hundred)
  • PPT, PPM, PPB
  • Molar solutions

g/L, µg/mL, etc.

How to make up a 10 g/L aqueous solution?

  • Weigh out 10 g of the substance.
  • Put it in a vol. flask or grad. cylinder
  • Add water up to the 1 L mark.

If you mix 1 L water with 10 g solute, then the total volume would be >1 L, and the concentration would be <10 g/L.

  • w/w = grams per hundred grams total (this applies to compounds in solid materials, too)
  • v/v = mL per hundred mL solution
  • w/v = g per hundred mL solution

Like percent, except more dilute

  • parts per thousand
  • parts per million
  • parts per billion

1 ppm = 1 µg/g = 1 µg/mL = 1 mg/L

Moles of solute per liter of solution

  • 1 mole is 6×1023 molecules.
  • The mass of 1 mole of a compound is the molecular weight (MW) of that compound.

The molarity of hydrogen ion equivalents produced by a compound in solution. (Usually applies to acids/bases.)

  • For many chemicals the molarity and normality are the same
  • 1M HCl is the same composition as 1N HCl Same for HNO3 , HF, most organic acids (e.g. HCOOH)

Occur when you are working with molecules with >1 exchangeable proton.

  • Sulfate, phosphate, carbonate 18M sulfuric acid (H2SO4) is 36N
  • There are 2 H+ ions (protons) per molecule
  • Multiply the molarity of a solution by the number of H+ to get normality
  • 5M phosphoric acid (H3PO4) is 15N

C1V1=C2V2

C1 = initial concentration
V1 = initial volume
C2 = desired final concentration
V2 = desired final volume

You need 100 ml of 1M NaCl and you have a stock solution of 5M NaCl

  • What do you know?
  • C1 = 5M
  • C2 = 1M
  • V2 = 100ml
  • Answer … solve for V1 = C2V2/C1
  • = 1M x 100 ml/5M = 20 ml of the stock

Special considerations for strong acids and bases

SAFETY: Whenever possible, add acid to water, not water to acid.

  • Important primarily for very concentrated acids
  • Prevents splashing & over-heating of acid

“Full-Strength” is not necessarily 100%

  • Ex.: 100% HCl is a gas! The most concentrated liquid form is a 36% aqueous solution.
  • So when diluting to make 10% HCl, you are starting from 36%, not 100%.

Also read: Project Planning and Delivery Lecture Presentation by Dr. Cornelia M. Wilson

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