solvent

Examples of solvent in the following topics:

• Solvent Effects

  • Polar, protic solvents such as water and alcohols solvate anions by hydrogen bonding interactions, as shown in the diagram below.
  • Polar, aprotic solvents such as DMSO (dimethyl sulfoxide), DMF (dimethylformamide) and acetonitrile do not solvate anions nearly as well as methanol, but provide good solvation of the accompanying cations.
  • Consequently, most of the nucleophiles discussed here react more rapidly in solutions prepared from these solvents.
  • These solvent effects are more pronounced for small basic anions than for large weakly basic anions.

• Putting benefit perception and service together

  • Safechem, a division of Dow Chemical, is a solvent distribution company that incorporates benefit perception and service into a portfolio range offered to general industries across Europe.
  • Its customers do not have to purchase the solvents they need to conduct their operations nor do they have to pay for costly application equipment or high disposal fees.
  • Instead, Safechem focuses on the benefits its customers seek by travelling to the place where its customers work and applying their needed solvents for them.
  • Afterwards, Safechem cleans up the work site, transports the used solvents back to Safechem, and cleans and/or recycles everything that was used – including the solvents, the washers, the spray guns and the steel drums – in preparation for the next customer.
  • By selling square metres of cleaning' rather than gallons of solvents, Safechem: (1) extends the life of its materials, (2) focuses on the benefits its customers seek, and (3) reduces waste and costs by reusing its materials instead of having to make (or buy) more.

• Water’s Solvent Properties

  • Water's polarity makes it an excellent solvent for other polar molecules and ions.
  • Oils, fats, and certain organic solvents do not dissolve in water because they are hydrophobic.
  • Water, which not only dissolves many compounds but also dissolves more substances than any other liquid, is considered the universal solvent.
  • Water is therefore referred to as a solvent: a substance capable of dissolving other polar molecules and ionic compounds.
  • Water is a poor solvent, however, for hydrophobic molecules such as lipids.

• The Leveling Effect

  • The leveling effect, or solvent leveling, is an effect that places an upper-limit on the strength of an acid (or base) in a given solvent when the solvent is Lewis acidic or Lewis basic.
  • The strength of a strong acid is limited ("leveled") by the basicity of the solvent.
  • Similarly, the strength of a strong base is leveled by the acidity of the solvent.
  • Strong bases are leveling solvents for acids, weak bases are differentiating solvents for acids.
  • Because of the leveling effect of common solvents, studies on super acids are conducted in solvents that are very weakly basic such as sulfur dioxide (liquefied) and SO2ClF (these solvents would be considered differentiating solvents).

• Solvent Effects

  • This characteristic is a function of the polarity of the solvent.
  • Solvents that have relatively acidic hydrogen atoms (e.g.
  • A list of common protic and aprotic solvents is provided here.
  • The dielectric constants provide a measure of solvent polarity.
  • This refers to the ability of solvent molecules to stabilize ions by encasing them in a sheath of weakly bonded solvent molecules, thus somewhat dispersing the electrical charge.

• Intermolecular Forces and Solutions

  • The strength of the intermolecular forces between solutes and solvents determines the solubility of a given solute in a given solvent.
  • In order to form a solution, the solute must be surrounded, or solvated, by the solvent.
  • Solutes successfully dissolve into solvents when solute-solvent bonds are stronger than either solute-solute bonds or solvent-solvent bonds.
  • In general, solutes whose polarity matches that of the solvent will generally be soluble.
  • In this case, the potential energy is lower when the solute and solvent can form bonds.

• Vapor Pressure of Nonelectrolyte Solutions

  • When a solute is added to a solvent, the vapor pressure decreases.
  • The vapor pressure of a solvent is lowered by the addition of a non-volatile solute to form a solution.
  • If the liquid solvent becomes "diluted" with solute, the entropy of the liquid state increases.
  • Overall, less solvent will transition to the gaseous phase, resulting in a decrease in vapor pressure.
  • In this equation, $p^{\star}_{\rm A}$ is the vapor pressure of the pure solvent and $x_{\rm A}$ is the mole fraction of the solvent.

• Heat of Solution

  • Heat of solution refers to the change in enthalpy when a solute is dissolved into a solvent.
  • The breaking of intermolecular attractive forces within the solvent, such as hydrogen bonds (endothermic)
  • This depends entirely on if more energy was used to break the solute-solute and solvent-solvent bonds, or if more energy was released when solute-solvent bonds were formed.
  • If more energy is used in breaking bonds than is released upon solute-solvent bond formation, then the overall process is endothermic, and ∆Hsol is positive.
  • Solute-solvent attractive bond formation (the exothermic step in the process of solvation) is indicated by dashed lines.

• Vapor Pressure of Electrolyte Solutions

  • The vapor pressure of an electrolytic solution is dependent on the ratio of solute to solvent molecules in a solution.
  • To better visualize the effect of solute on the vapor pressure of a solution, consider a pure solvent.
  • This pure solvent has a certain vapor pressure associated with it.
  • Now consider a solution composed of both solvent and solute.
  • Compare the relative vapor pressures of a pure solvent and an electrolyte solution composed of the same solvent

• Molality

  • Molality is a property of a solution that indicates the moles of solute per kilogram of solvent.
  • The SI unit for molality is mol/kg, or moles solute per kg of solvent.
  • It is easy to calculate molality if we know the mass of solute and solvent in a solution.
  • Remember that molality is moles of solute/kg per solvent.
  • KCl is our solute, while water is our solvent.