Chapter Four-Solutions and Solubility Flashcards
Define solvent.
Any substance that has other substances dissolved in it.
Fill in the blanks. A solution is a __________________, meaning it is _____________ throughout.
A) Homogeneous mixture
B) Uniform
Define solute.
Substances that are present in the solution.
Define variable composition.
Different ratios of solvent to solute.
Does a chemical rxn occur when a solute dissolves in a solvent?
No.
What states can a solution occur in?
A solution can be a gas, liquid or solid.
Describe the difference b/w sq and solid solutions.
Aqueous solutions: water is the solvent, liquids where any amount dissolved in water are miscible (ethanol and water) , liquids that do not relatively dissolve in each other are immiscible (oil and water). Solid solutions (alloys): adding small quantities of another element to a metal, which in turn, changes its properties. Ex. Copper+Tin=Bronze
Describe the solubility of a solute.
It is the amount of solute that dissolves in a given quantity of a solvent at a certain temperature.
Describe saturated solution.
It is formed when no more solute will dissolve in a solution, and excess solute is present.
Describe unsaturated solution.
A solution that is not yet saturated, can dissolve more solute.
State the three factors that affect the rate of dissolving.
Temperature: rate of dissolving is greater at higher temperatures (greater Ek=colliding)
Agitation: by stirring or shaking container increases dissolving (brings into contact)
Particle size: decreasing the particle size will increase the rate of dissolving (sugar cube vs packet, increase SA that is in contact with solvent)
Fill in the blanks. When the forces of attraction b/w different particles in a mixture are ___________ than the forces of attraction between like particles in the mixture, a ___________ forms. The strength of each attraction influences ________________ or the amount of solute that dissolves in a __________.
A) Stronger
B) Solution
C) Solubility
D) Solvent
Fill in the blanks. The process of Dissolving at the Molecular Level: The forces b/w the particles in the solid must be ____________. This step always requires ______________. In an ionic solid, the forces that are holding the ions together must be _________________. In a molecular solid, the forces b/w the molecules must be __________. Some of the intermolecular forces b/w the particles in the liquid must be ________. This step also requires __________. There is an attraction b/w particles of the solid and particles of the liquid. This step always gives off _________.
A) Broken B) Energy C) Broken D) Broken E) Broken F) Energy G) Energy
True or False. Polar compounds dissolve in polar solvents and DO NOT dissolve in non-polar solvents.
True.
True or False. Non-polar compounds dissolve in polar solvents, and DO NOT in non-polar solvents.
False. Non-polar compounds dissolve in non-polar solvents, and DO NOT in polar solvents.
What is a dipole?
Two opposite charges that are separated by a short distance.
What is a dipole-dipole attraction?
The attraction b/w opposite charges on 2 different polar molecules. (intermolecular b/w molecules, in water,, hydrogen bonding; it occurs b/w the oxygen atom on one molecule and the hydrogen atoms on a nearby molecule, 1% as strong as ionic or covalent bond hydrogen bonding is much stronger than ordinary d-d attraction)
Describe Ion-Dipole Attractions.
Ionic crystals consist of repeating patterns of oppositely charged ions when they come into contact w/ water, the - end of dipole on some water molecules attracts the cations on the surface of the ionic crystal. At the same time, the + end of water dipole attracts anions. ATTRACTIVE FORCES B/W ION AND A POLAR MOLECULE an ionic compound will dissolve in a polar solvent, when ions are hydrated they will conduct electricity=electrolyte)
Describe the exception of Insoluble Ionic Compounds
Attraction b/w ions is difficult to break, compounds w/ very strong ionic bonds tend to be less soluble in water than compounds with weak ionic bonds.
How do you predict the solubility of a binary compound?
You must determine the electronegativity of each element; a big difference between these values will allow you to see it is ionic or polar (dissolves in water) and a small difference between these values will allow you to see it is nonpolar (does not dissolve in water).
Fill in the blanks. Covalent compounds do not have the _________________ or ______________ to attract water molecules. Methanol, ethanol and sugars are extremely soluble, they ____________________ because their molecules contain _______________, which are able to form _____________ with water.
A)Positive charges B)Negative charges C)Dissolve D)Polar bonds E)Hydrogen bonds
How do sucrose molecules dissolve?
They have a number of sites that can form hydrogen bods with water to replace the attraction between sucrose molecules. They separate and become hydrated like dissolved ion molecules that remain neutral, no current, non-electrolytes.
True or False. Benzene and Kerosene are non-polar solvents; therefore, they can dissolve non-polar solvents.
True.
Did you know? Forces between the solute molecules are replaced by forces b/w the solvent and solute molecules?
Because you should!
Fill in the blank. Ionic solutes and polar covalent solutes dissolve in _______________________.
Polar solvents
