Chemistry Lab/Acids and Bases

This page refers to the 2009 focus of Chem Lab.

Acids and Bases (2009)
Acids and Bases is basically an acid/base titration lab. Be sure you know what a titration is, because it is not a good thing if you do not. This is a fairly quick and simple lab to complete, and it is more than worthwhile to double check your lab if you have enough materials. More repetitions of the lab can result in a more accurate answer. In a free-response style lab report, this might also get you some extra points for style and accuracy. Acid/base questions can range in difficulty from identifying if a solution was an acid based on its pH to balancing advanced reactions trying to find the acidic constant. In order to excel in this event you must be prepared for all levels.

Solute
The solute is what is being dissolved. For example, when dissolving salt in water, the salt is the solute.

Solvent
The solvent is what is dissolving the solute. For example, when dissolving salt in water, the water is the solvent.

Solution
A solution is the combination of a solute and a solvent.

Because of the fact that in most solutions the amount of solute is relatively small compared to the amount of solvent, you may usually assume that the volume of solution is the same as the volume of solvent.

Moles
No, not the animal. A mole (abbreviate mol) is a number. Just like a dozen refers to the number 12, a mole refers to the number 6.022E23.

The way scientists came up with this seemingly random number originated with elements and their molar masses. The mole is designed so that amu is the same thing as g/mol. This is useful if you want to figure out the number of atoms in a gram.

Equilibrium
Equilibrium is where the rate of reaction forward is equal to the rate of reaction backwards. Basically, it is where the amount of reactant and the amount of product are not changing.

Acids
All acids have a pH less than 7

Arrhenius Acids
Arrhenius Acids are defined to be chemicals that, when put in water, produce hydronium (H3O+) ions.

Bronsted-Lowry Acids
Bronsted-Lowry Acids are defined to be chemicals that donate protons (H+). This is a broader definition than the Arrhenius definition because it does not have to involve water.

Lewis Acids
Lewis Acids are defined to be chemicals that accept electron pairs.

Bases
All bases have a pH greater than 7.

Arrhenius Bases
Arrhenius Bases are defined to be chemicals that, when put in water, produce hydroxide (OH-) ions.

Bronsted-Lowry Bases
Bronsted Lowry Acids are defined to be chemical that accept protons (H+). This is a broader definition than the Arrhenius definition because it does not have to involve water.

Lewis Bases
Lewis Bases are defined to be chemicals that donate electron pairs.

Titration
Titrations are where acids and bases are mixed together to figure out some unknown quantity from multiple known quantities.

pH
pH is equal to the -log[H+] or -log[H3O+]. It is equal to 14-pOH.

pOH
pOH is equal to the -log[OH-]. It is equal to 14-pH.

Concentration
Concentration is typically expressed as [solute]. This expression means the concentration of the solute, usual expressed in terms of Molarity.

Molarity
Molarity or Molar concentration (abbreviated M) is equal to moles of solute over liters of solution.

Mass Concentration
Mass Concentration is equal to grams of solute over liters of solution.

Mole Fraction
Mole Fraction is equal to the moles of solute over the moles of solution.

Molality
Molality is equal to the moles of solute over the mass of the solvent (not the solution).

Equilibrium Constants
Take this reaction:

aA + bB -> cC + dD

The equilibrium constant is equal to:

([C]^c * [D]^d)/([A]^a * [B]^b)

Where all of the concentrations are the concentrations at equilibrium and where solids are excluded.

The equilibrium constant tells you where equilibrium occurs.

Solubility Product Equilibrium Constant
The solubility product equilibrium constant (Ksp) is equal to

[A+][B-]

for the following reaction:

AB -> A+ + B-

Unsaturated
Unsaturated solutions are solutions where the Ksp has not yet been reached.

Saturated
Saturated solutions are solutions where the Ksp has been reached.

Super Saturated
Super Saturated solutions are where the Ksp has been reached and gone over. These solutions can be achieved by heating up a solvent (heat causes the Ksp to increase), adding a solute, and then letting the solution cool.

Miscible
Two things are considered miscible when they can be mixed uniformly in any quantities.

Acid Dissociation Constant
The acid equilibrium constant (Ka) is equal to

[H+][A-]/[HA]

for the following reaction:

HA -> H+ + A-

Base Dissociation Constant
The base dissociation constant (Kb) is equal to

[BH+][OH-]/[B]

for the following reaction:

B + H2O -> BH+ + OH-

Links

 * Acid and base links