CHAPTER 1

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SOLUBILITY AND SOLUTIONS

Factors that affect solubility-Solute-Solvent Interactions-Pressure Effects (dissolving gases)-Temperature Effects (for both gaseous and solid solutes) Solution -A solution is a homogenous mixture when one substance (solute) is dissolved into another (solvent). -An aqueous solution is dissolved in water.-They are a physical change.-There are no new substances being produced. -The particles of the solute and solvent merely physically

mix and do not undergo a chemical change.

SOLUTE VS. SOLVENT

-A solute is the substance to be dissolved such as sugar. It is usually a solid and is the smaller part of the solution.

-The solvent is the one doing the dissolving such as water. It accepts the solute. The most common is H20, meaning most solutions are aqueous.

-In a solution of salt and water, salt is the solute and water is the solvent.

DISSOLUTION AND ELECTROLYTES

Rates of Dissolution

-The rate of dissolution quantifies the speed of the dissolution process.

-It depends on the nature of the solvent and solute, temperature, degree of under saturation, presence of mixing, and surface area.  

Electrolytes

-An electrolyte is a substance that dissolves in water to give a solution that conducts electric current

-When ionic solids dissolve in water, the positive and negative ions separate from each other and are free to move around.

-Electrolytes can be strong (all pieces dissociate into ions) or weak (some form ions some don’t).

SATURATED VS. UNSATURATED, DILUTE VS. SUPERSATURATED, MISCIBLE AND IMMISCIBLE

Saturated vs. Unsaturated-Saturated contains the maximum amount of solute for a given

quantity of solvent at a constant temperature and pressure.

-Unsaturated contains less solute than a saturated solution at a given temperature and pressure.

Dilute vs. Supersaturated-Dilute is very few particles in the solution.

-Supersaturated contains more solute than it can theoretically hold at a given temperature.

Miscible and Immiscible-Two liquids are miscible if they dissolve in each other in all

proportions.

-Liquids that are insoluble in one another are immiscible.

MOLARITY

-Molarity is an exact way to represent concentration.

-Molarity (M) = # moles of solute in 1 L of solution

-Molarity (M)= # moles of solute (mol)

volume of solution (L)

When given g and L and asked to find M use: M= mol

V

When given mol and L and asked to find V use: V= mol x M

When given M and L and asked to find mol use: mol= V x M

MOLARITY PRACTICE PROBLEM

Calculate the molarity when 75.0 grams of MgCl2 is dissolved in 500.0 mL of solution.

*Convert mL to L (mLx1000)

*Use molar mass to find moles. Then divide by volume to find M.

CONCENTRATION

-A solution be changed either by adjusting the volume or the solute.

-Adding solvent will dilute concentration.

-Removing solvent increases concentration.

-Formula to help: MiVi=MfVf

-i= initial, f=final

*pay attention to initial and final volumes when doing change in concentration problems

CONCENTRATION PRACTICE PROBLEM

A student pours 60mL of 2.0 HCl acid into a beaker containing 240 mL of water. What is the new concentration of this acid?

*Be sure to use correct final volume.