CHEM EXAM 3

Boyle’s Law

P_i x V_i = P_f x V_f

What does Boyle’s law represent?

When the pressure on a gas is doubled, the volume of the gas will be reduced to half of its initial volume

= the volime of a fixed amount of gas is proportional to the pressure

Charles’s Law

V_i = V_f / T_i = T_f

What does Charles’s law represent?

The volume of a fixed amount of gas at a constant pressure is directly proportional to its absolute temperature

London forces (most weakest)

• all molecules have LF

• attractive force nonpolar molecules participate in

Dipole-Dipole forces (second weakest)

• involves polar molecules

• the attraction of two dipoles

Hydrogen Bonds (strong)

• involves a polarized hydrogen

• can occur between the same molecule, two different molecules, or between different parts of the same molecule

Ion-Dipole (stronger)

• occurs between ionic charges and polar molecules

Ion Attraction (Strongest)

• occur when oppositely charged ions attract each other

• also called salt bridges

What kind of attraction do alkanes have?

London forces because they’re nonpolar

Golden rule for solubility

Like dissolves like

Predict the water solubility of nonpolar compounds

• only have LF

• NPC are insoluble in water

What is attractions is water soluble with?

Dipole-Dipole, hydrogen bonding, and ion-dipole

Predict the water solubility of polar compounds

• Because PC experience D-D and hydrogen bonding they’re soluble in water

Predict the water solubility of ionic compounds

• Because IC experience I-D attractions, they’re soluble in water

What are amphiphatic compounds?

Compounds that have both polar and nonpolar parts.

Hydrogen bonds

• H bonded to N, O, F

• lone pairs of electrons on N (1LP), O (2 LP), F (3LP)

What is a solution?

Consist of atleast one substance (the solute) evenly dispersed in a second substance (the solvent)

Solvent

The substance present in a greater amount

Solute

The substance present in the smaller amount

Strong electrolytes

Ionic compounds that dissolve in water

Nonelectrolytes

Soluble covalent compounds that do not ionize (dissociate to form ions) in water

Weak electrolytes

Covalent compounds that partially ionize in water

What determines a solutions concentration?

The amount of solute dissolved in a solution determine its concentration

Molarity

M = mole solute / L solution

Percent mass/mass

% (m/m) = g solute / g solution x 100%

*typically used when liquids or gases are the solute and solvent

Percent mass/volume

% (m/v) = g solute / mL solution x 100%

*typically used when solute is a solid and the solvent is a liquid

Dilution eq.

C_iV_i = C_fV_f

When identifying acids and bases, an acid is the one that

gets rid of the proton (H+)

When identifying acids and bases, a base is the one that

accepts the proton (H+)

The products of neutralization reactions is always

Salt and water

Equilibrium constant eq.

K = [products] / [ reactants]

*remember state of matter is important only gases are included

Degrees Fahrenheit from Celsius

F = (1.8)(C)+32

Degrees Celsius from Farenheit

C = (F-32) / 1.8

How to go to moles from grams?

Look at the atomic mass of the element on the periodic table

Eq. for finding pH

pH = - log [H+]

Eq. for finding [H+]

[H+] = 10 ^{- pH}

pH

acidic : 1-6

neutral: 7

basic: 8-14

When balancing neutralization reactions the products are always..

a salt and a water