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Chemistry LibreTexts

Quantifying Nature

  • Page ID
    348
  • Quantitative analysis is the determination of the absolute or relative abundance (often expressed as a concentration) of one, several or all particular substance(s) present in a sample.

    • Accuracy of Spectrophotometer Readings
      he needle deflection or the number shown on the digital display of a spectrophotometer is proportional to the transmittance of the solution. How do errors in transmittance readings affect the accuracy of solution concentration values?
    • Density and Percent Compositions
      Density and percent composition are important concepts in chemistry. Each have basic components as well as broad applications. Components of density are: mass and volume, both of which can be more confusing than at first glance. An application of the concept of density is determining the volume of an irregular shape using a known mass and density. Determining Percent Composition requires knowing the mass of entire object or molecule and the mass of its components.
    • Significant Digits
      Significant Digits - Number of digits in a figure that express the precision of a measurement instead of its magnitude. The easiest method to determine significant digits is done by first determining whether or not a number has a decimal point. This rule is known as the Atlantic-Pacific Rule. The rule states that if a decimal point is Absent, then the zeroes on the Atlantic/right side are insignificant. If a decimal point is Present, then the zeroes on the Pacific/left side are insignificant.
    • Temperature Basics
      The concept of temperature may seem familiar to you, but many people confuse temperature with heat. Temperature is a measure of how hot or cold an object is relative to another object (its thermal energy content), whereas heat is the flow of thermal energy between objects with different temperatures. Three different scales are commonly used to measure temperature: Fahrenheit (expressed as °F), Celsius (°C), and Kelvin (K).
    • The Scientific Method
      The Scientific Method is simply a framework for the systematic exploration of patterns in our world. It just so happens that this framework is extremely useful for the examination of chemistry and its many questions. The scientific process, an iterative process, uses the repeated acquisition and testing of data through experimental procedures to disprove hypotheses.
    • Units of Measure
      Most of these quantities have units of some kind associated with them, and these units must be retained when you use them in calculations. Measuring units can be defined in terms of a very small number of fundamental ones that, through "dimensional analysis", provide insight into their derivation and meaning, and must be understood when converting between different unit systems.

    Thumbnail: The seven SI base units and their interdependency. Clockwise from top left: second (time), metre (distance), Ampere (electric current), mole (amount of substance), kilogram (mass), Kelvin (temperature) and candela (luminous intensity). Image used with permission (CC BY-SA 3.0; Dono)