Chapter 18

a substance that yields hydrogen ions (H+) when dissolved in water

a substance that yields hydroxide ions (OH-) when dissolved in water

a proton (H+ ion) donor

a proton acceptor

the power to which a concentration of a reactant is raised in a rate law

the net movement of solvent through a semi-permeable membrane toward the solution with greater concentration

a law stating that the concentration of a gas in a solution is proportional to the pressure of that gas over the solution

a substance that increases the speed of a chemical reaction without itself undergoing a permanent change

a detailed picture or model of how a chemical reaction occured

a substance formed in one elementary step and consumed in a later elementary step

the number of particles that participate as reactants in an elementary step

liquids that mix in all proportions

the ratio of a concentration or pressure to a standard concentration or pressure

an acid DONATES a proton and then becomes a base while a base ACCEPTS a proton and then becomes an acid; such a pair of species is called a conjugate acid-base pair

a substance that has the ability to sometimes act as an acid and to sometimes act as a base; ex. water

• even in pure water some water molecules will act as acids and donate protons to other water molecules that are acting as bases
• H₂O(l) + H₂O(l) <---> H₃O+(aq) + OH-(aq)
• it gets its own eq. constant (at room temperature), k_w=1.00 x 10^-14

endothermic; as temperature increases, so does k_w

if you know the concentration of one, you can calculate the concentration of another (at room temperature)

[H] is a unitless activity

the portion to the right of the decimal points; in a logarithm only the digits to the right are significant

• p______ = -log________
• @ room temperature pH + pOH = 14

a DEcrease in pH by 1 unit corresponds to an INcrease in H+ by a factor of 10

a greater acidity is not due to acid concentration, instead it is due to a more COMPLETE ionization

COMPLETE ionization; an acid/base that doesn't ionize to completion is WEAk

• HCl
• HBr
• HI (!)
• H₂SO₄
• HNO₃ (nitrate)
• HClO₄
• Chemistry Brings Infinite Sorrow. Not Cool.

the two left-most columns of the periodic table (EXCEPT BERYLLIUM) paired with OH^- are strong bases (not all are super soluble)

the stronger the base of a pair, the weaker the acid

an acid that's capable of donating more than one proton to a base; the donation of each proton becomes progressively less likely, therefore each constant (k_a) has a different value

the percent ionization is GREATER for more dilute solutions

• bleh. same for log form.
• Kw at room temp (25 deg C) = 1.00 x 10^-14

BASE! BASEBASEBASEBASE

CONCENTRATION!!!! Why wouldn't you?

it's STRONG, so it dissociates on its own, it doesn't need water; if it's WEAK you add water because you can assume that not all of it will dissociate into ions

when you add another gas but keep the total pressure the SAME, think about the gasses already present in the reaction have to DECREASE their partial pressures to compensate for you adding that other gas; (ex: if both have a p.pressure of .5 but then you add and extraneous gas that has a p.pressure of .2 and the total pressure STAYS at 1 atm, the two gasses that started out in the system must DECREASE in pp to compensate for the addition of a new gas!)

moles OR pressure of a gas being used in a reaction

water makes all strong acids appear to be equivalent in their extent of ionization (ie 100%); using a solvent that's less acetic than water (such as ammonia) will remove the leveling effect for strong bases