concentration

Examples of concentration in the following topics:

• Diffusion

  • Diffusion is the movement of particles from regions of high concentration towards regions of lower concentration.
  • Diffusion is the movement of particles move from an area of high concentration to an area of low concentration until equilibrium is reached .
  • Diffusion explains the net flux of molecules from a region of higher concentration to one of lower concentration.
  • However, diffusion can still occur in the absence of a concentration gradient.
  • Particles moving from areas of high concentration to areas of low concentration.

• Osmosis

  • Osmosis is the movement of water across a membrane from an area of low solute concentration to an area of high solute concentration.
  • Water, like other substances, moves from an area of high concentration to one of low concentration.
  • Water has a concentration gradient in this system.
  • Thus, water will diffuse down its concentration gradient, crossing the membrane to the side where it is less concentrated.
  • In osmosis, water always moves from an area of higher water concentration to one of lower concentration.

• Concept of Osmolality and Milliequivalent

  • Solution concentration is expressed by a solution's molality, while electrolyte concentration is expressed in terms of milliequivalents per liter.
  • In order to calculate osmotic pressure, it is necessary to understand how solute concentrations are measured.
  • Molarity and molality represent solution concentration, but electrolyte concentrations are usually expressed in terms of milliequivalents per liter (mEq/L).
  • The milliequivalent unit incorporates both the ion concentration and the charge on the ions.
  • Concentration of solutions; part 2; moles, millimoles & milliequivalents by Professor Fink

• Dilutions of Solutions

  • Diluting a solution involves adding additional solvent to decrease the solution's concentration.
  • Dilution refers to the process of adding additional solvent to a solution to decrease its concentration.
  • Dilution can also be achieved by mixing a solution of higher concentration with an identical solution of lesser concentration.
  • What is the final concentration of the diluted solution?
  • As is evidenced in this example, the concentration is reduced by a factor of ten in each step.

• Changes in Concentration

  • The effect of changes in the concentration of products and reactants in a reversible reaction can be predicted by Le Chatelier's Principle.
  • If a chemical system at equilibrium experiences a change in concentration, temperature, volume, or partial pressure, then the equilibrium shifts to counteract the imposed change.
  • Changing the concentration of an ingredient will shift the equilibrium toward the side that reduces the concentration change.
  • Suppose we were to increase the concentration of CO in the system.
  • Evaluate how a change in concentration will affect a chemical equillibrium

• Minimal Inhibitory Concentration (MIC)

  • Minimum Inhibitory Concentration is the lowest drug concentration that prevents visible microorganism growth after overnight incubation.
  • In microbiology, minimum inhibitory concentration (MIC) is the lowest concentration of an antimicrobial (like an antifungal, antibiotic or bacteriostatic) drug that will inhibit the visible growth of a microorganism after overnight incubation.
  • The minimum inhibitory concentration of the antibiotic is between the concentrations of the last well in which no bacteria grew and the next lower dose, which allowed bacterial growth.
  • To identify the lowest concentration required for a given antibiotic to inhibit bacterial growth, an identical amount of bacteria is introduced into wells of liquid media containing progressively lower concentrations of the drug.
  • Because bacterial growth made the media in well E5 cloudy and the media in well E4 is indistinguishable from clear media, this indicates that the minimum inhibitory concentration is between the drug concentrations in wells E4 and E5.

• Concentrated Targeting

  • Concentrated marketing is a strategy which targets very defined and specific segments of the consumer population.
  • An organization that adopts a concentration strategy chooses to focus its marketing efforts on only one very defined and specific market segment.
  • For example, the manufacturer of Rolex watches has chosen to concentrate on the luxury segment of the watch market.
  • The primary disadvantage of concentration strategy is related to the demand of the segment.
  • Evaluate the advantages and disadvantages of adopting concentration strategies in consumer marketing

• Calculating Equilibrium Concentrations

  • Since we know what our Kc value  is and the initial concentrations of reactants, we can set up an ICE chart to track the changes in concentration, as the reaction proceeds towards equilibrium.
  • We can designate x as the change in concentration of N2 and O2.
  • Knowing the initial concentration values and equilibrium constant we were able to calculate the equilibrium concentrations for N2, O2 and NO.
  • The equilibrium concentration is the sum of the initial concentration and the change, which is derived from the reaction stoichiometry.
  • Calculate the concentrations of reaction components at equilibrium given the starting concentrations and the equilibrium constant

• Diffusion

  • Diffusion is a process of passive transport in which molecules move from an area of higher concentration to one of lower concentration.
  • This is due to the diffusion of odor molecules through the air, from an area of high concentration (the kitchen) to areas of low concentration (your upstairs bedroom).
  • A single substance tends to move from an area of high concentration to an area of low concentration until the concentration is equal across a space .
  • The ammonia gas is at its highest concentration in the bottle; its lowest concentration is at the edges of the room.
  • Extent of the concentration gradient: The greater the difference in concentration, the more rapid the diffusion.

• Direct Counting

  • Direct counting methods are used to determine bacterial concentration without the need for advanced equipment.
  • On almost all occasions, what gets counted is actually the concentration of the cells (for example: 5,000 cells per milliliter).
  • By counting the cells in a known volume of a culture, the concentration can be assessed.
  • In medicine, the concentration of various blood cells, such as red blood cells or white blood cells, can give crucial information regarding someone's health.
  • The colonies can then be counted and, based on the known volume of the culture that was spread on the plate, the cell concentration can be calculated.