Transformation of a molecule from a liquid to a gas.

Also known as: Evaporation

Quantity of heat that a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state.

Relatively high heat of vaporization, requiring about 580 cal of heat to evaporate 1g of water at room temp.

The heat of vaporization of water requires double the heat required to vaporize the same quantity of alcohol or ammonia.

This is because hydrogen bonds must be broken before a water molecule can evaporate from the liquid.

Water is less dense as a solid than as a liquid.

At temperatures above 4 degrees C, water expands when it warms and contracting when it cools.

Water begins to freeze when its molecules are no longer vigorously enough to break their hydrogen bonds.

The sum of the weight of all the parts of atoms in a compound (expressed in daltons)

e.g. NaCl

Na = 23 and Cl = 35.5

MW = 23 + 35.5 = 58.5 daltons

Na=23 and Cl=35.5

NaCl = 58.5 daltons

2x58.5 = 117

117 g of NaCl, add water until the total volume was 1 liter

The actual number of molecules in a mole

6.02 x 10²³

Mole of sucrose contains 6.02 x 10²³ molecules and weighs 342g; while mole of ethyl alcohol also contains 6.02 x 10²³ molecules but weighs only 46g.

This is because molecules in Ethanol are smaller than Sucrose.

What are acids?

Give an example of an acid.

Substances that INCREASE the relative concentration of [H⁺] in a solution.

Ex: (in water)

HCL ---> H⁺ + Cl^-

Thus, hydrochloric acid increases the # of H⁺ ions making the solution more Acidic.

What are bases?

Give an example of an base.

Substance that REDUCE the relative concentration of [H⁺] in a solution.

Reduce [H⁺] directly:

NH³ + H⁺ ---> NH⁴⁺

Reduce [H⁺] indirectly:

NaOH ---> Na⁺ + OH^-

OH^- + H⁺ ---> H₂O

H₂CO₃ (Carbonic Acid) + NaHCO₃ (Sodium BiCarbonate)

or NH₃ (Ammonia) + NH₄Cl (Ammonium Chloride)

If you add a Strong Base to Buffer, it forms a Weak Base + Water

If you add a Strong Acid to Buffer, it forms a Weak Acid + Salt