precipitate

(noun)

A solid that exits the liquid phase of a solution.

Related Terms

  • chemical formula
  • chemical equation
  • reactant
  • product
  • solubility
  • anion
  • cation
  • insoluble
  • spectator ion
  • limestone

(verb)

To come out of a liquid solution into solid form.

Related Terms

  • chemical formula
  • chemical equation
  • reactant
  • product
  • solubility
  • anion
  • cation
  • insoluble
  • spectator ion
  • limestone

Examples of precipitate in the following topics:

  • Precipitation Reactions

    • Precipitation reactions transform ions into an insoluble salt in aqueous solution.
    • Precipitation refers to a chemical reaction that occurs in aqueous solution when two ions bond together to form an insoluble salt, which is known as the precipitate.
    • The following is a common laboratory example of a precipitation reaction.
    • A final way to represent a precipitation reaction is known as the net ionic equation.
    • Distinguish ways to write precipitation reactions (complete ionic equation and net ionic equation) and use a solubility table to determine whether a precipitation reaction will occur
  • Ion Separation by Fractional Precipitation

    • Silver chloride (AgCl) is not soluble and forms a white precipitate.
    • So how does one tell if the precipitate is a carbonate or a chloride?
    • If the precipitate remains unchanged, then the salt is a chloride.
    • Bromides and iodides also form precipitates when they are reacted with silver nitrate, but both precipitates are pale yellow.
    • Which ion will precipitate first?
  • Predicting Precipitation Reactions

    • Sometimes ions in solution react with each other to form a new substance that precipitates; this reaction is called a precipitation reaction.
    • A precipitate, which looks like light blue specks of dust, forms.
    • No precipitate forms.
    • Therefore Na2CO3 will remain in solution, but CuCO3 will precipitate out.
    • This is why no precipitate forms in this second reaction.
  • Chemical Analysis

    • Two common techniques are precipitation analysis and colorimetric analysis.
    • The color of the precipitate will indicate the metal.
    • Barium, calcium, and strontium will precipitate at this point, but not before.
    • However, precipitation methods similar to those mentioned above are often used.
    • Difference in the visual appearance of an aggregate and a precipitate.
  • Solubility Product Principle and Qualitative Analysis

    • Solubility-product constants can be used to devise methods for separating ions in a solution by selective precipitation.
    • Selective precipitation is used to form a solid with one of the ions in solution without disturbing the other ions.
    • Can either Ba2+ or Sr2+ be precipitated selectively with concentrated sodium sulfate (Na2SO4) solution?
    • Which ion will precipitate first?
    • Precipitation is used in qualitative chemical analysis.
  • Molecular, Ionic, and Complete Ionic Equations

    • Precipitation reactions can be written as molecular, ionic, or complete ionic equations.
    • There are various ways to write out precipitation reactions.
    • On the right hand side of the equation, the precipitant (AgCl) is written in its full formula and designated as a solid, since this is the precipitate that is formed in the reaction.
    • In this representation, the ions that are uninvolved in the precipitation reaction ($Ca^{2+}$ and $NO_{3}^{-}$) are simply excluded from the reaction, because they are essentially redundant on both the left and right side.
    • Silver chloride is a precipitant of silver and chloride ions reacting in solution.
  • Effect of a Common Ion on Solubility

    • Adding a common ion decreases the solubility of a solute, causing it to precipitate.
    • When equilibrium is shifted toward the reactants, the solute precipitates.
    • In the water treatment process, sodium carbonate salt is added to precipitate the calcium carbonate.
    • The very pure and finely divided precipitate of calcium carbonate that is generated is used in the manufacture of toothpaste.
    • Lithium hydroxide forms less-soluble lithium carbonate, which precipitates because of the common ion effect.
  • Copper

    • Adding aqueous sodium hydroxide causes the precipitation of light blue solid copper (II) hydroxide.
    • Aqueous ammonia results in the same precipitate.
    • Upon adding excess ammonia, the precipitate dissolves, forming tetraamminecopper (II):
    • Aqueous ammonia results in the same precipitate.
    • Upon adding excess ammonia, the precipitate dissolves, forming tetraamminecopper(II):
  • Measuring Reaction Rates

    • In a reaction in which a precipitate is formed, the amount of precipitate formed in a period of time can be used as a measure of the reaction rate.
    • For example, when sodium thiosulphate reacts with an acid, a yellow precipitate of sulfur is formed.
    • However, as the reaction progresses and more precipitate is formed, the cross will gradually become less clear and will eventually disappear altogether.
    • By using a stopwatch to time how long it takes for the cross to disappear, and then massing the amount of precipitate formed during this time, an average reaction rate can be calculated.
  • Oxidation

    • This deep blue reagent is reduced to cuprous oxide, which precipitates as a red to yellow solid.
    • To avoid precipitation of the insoluble metal hydroxides, the cations must be stabilized as complexed ions.
Subjects
  • Accounting
  • Algebra
  • Art History
  • Biology
  • Business
  • Calculus
  • Chemistry
  • Communications
  • Economics
  • Finance
  • Management
  • Marketing
  • Microbiology
  • Physics
  • Physiology
  • Political Science
  • Psychology
  • Sociology
  • Statistics
  • U.S. History
  • World History
  • Writing

Except where noted, content and user contributions on this site are licensed under CC BY-SA 4.0 with attribution required.