1 / 8

lecture 5.; concentration units by Dr. Salma Amir

different concentration units in analytical chemistry

salmaamirfcw
Download Presentation

lecture 5.; concentration units by Dr. Salma Amir

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture No. 05Course title:Fundamental Analytical ChemistryTopic: Concentration units Course instructor: Dr. Salma Amir GFCW Peshawar

  2. Concentration units • Concentration: Concentration is a general measurement unit stating the amount of solute present in a known amount of solvent or solution • Concentration = • Expressed as 1. Molarity 2. Molality 3. Normality 4. Formality 5. % concentration 6. ppm, ppb, ppt

  3. 1. Molarity • Molarity is defined as the number of moles of solute dissolved per liter of solution and may be calculated by dividing the number of moles dissolved by the number of liters of solution: M= • For example, solutions are referred to as being 2.0 molar, or 2.0 M. The M refers to molar, and the solution is said to have a molarity of 2.0, or 2.0 mol dissolved per liter of solution. • It is important to recognize that, for molarity, it is the number of moles dissolved per liter of solution and not per liter of solvent.

  4. 2. Molality • Molality (m) is concentration expressed as moles of substance per kilogram of solvent (not total solution). m= • Molality is independent of temperature. Molarity changes with temperature because the volume of a solution usually increases when it is heated.

  5. 3. Normality • Normality (N) is expressed as , The number of equivalents of solute per liter of solution. Or Normality is the number of equivalent weights (EW) per unit volume. N= • Equivalent: The moles of a species that can donate one reaction unit. • Equivalent weight: The mass of a compound containing one equivalent (EW). EW=

  6. 4. Formality • Formality is concentration expressed as formula weight of substance per litre of solution F =

  7. Percent composition • Weight percent (% w/w), volume percent (% v/v) and weight-to-volume percent (% w/v) express concentration as units of solute per 100 units of sample. Or The percentage of a component in a mixture or solution is expressed as a percent (%): • weight percent Grams of solute per 100 g of solution. (% w/w). • volume percent Milliliters of solute per 100 mL of solution (% v/v). • weight-to-volume percent Grams of solute per 100 mL of solution (% w/v).

  8. ppm, ppb and ppt • Sometimes composition is expressed as parts per million (ppm) or parts per billion (ppb), which mean grams of substance per million or billion grams of total solution or mixture • parts per million Micrograms of solute per gram of solution; for aqueous solutions the units are often expressed as milligrams of solute per liter of solution (ppm). • parts per billion Nanograms of solute per gram of solution; for aqueous solutions the units are often expressed as micrograms of solute per liter of solution (ppb). • parts per trillion Picogramsof solute per gram of solution; for aqueous solutions the units are often expressed as nanogramsof solute per liter of solution (ppb).

More Related