exam 2 chem 151 lcc

electrolytes

substances that produce ions when dissovled in h2o

nonelectrolytes

substances that do not produce ions when dissolved in h2o

solvent

substance that dissolves the solute

solute

substance that is dissolved by solvent

dissociation

only left with ions

decomposition

breaks up into elements

weak electrolytes

only dissociate partially when dissolved

weak electrolyte examples

insoluble and highyl soluble salts, weak acids and weak bases; NH3, ammonia, is a weak acid

strong electrolytes

dissociate completely in h2o

strong electrlyte examples

soluble salts, strong acids and bases; HC2H3O2, acetic acid, breaks into ions

nonelectrolyte examples

molecular compounds besides acids, alcohols (C2H5OH), sugars (C2H12O6)

water soluble

group 1a salts

water soluble

no3

water soluble

nh4

water soluble

c2h3o2

water soluble

cl

water soluble

br

water soluble

i

water soluble

so4

insoluble

ag

insoluble

pb

insoluble

hg2

insoluble

ba

insoluble

sr

insoluble

oh

insoluble

s

insoluble

co3

precipitation reactions

reactions between aqueous solutions of ionic compounds that produce an ionic compound that is insoluble in water

insoluble product is called

precipitate

how do we predict precipitate production?

sollubility rules

what equation types do we use

ioninc, molecular, net ionic

bases

bases are substances that produce OH ions when dissolved in water

strong bases

bases that are strong electrolytes

examples of strong bases

group 1a metal hydroxides, heavy 2a metal hydroxides

weak bases

bases that are weak electrolytes, primarily containing nonmetals

weak bases work by

removing a hydrogen ion from water

NH3+H2O-> NH4+OH

molarity

concentration; measure of how much solute is in a solution

acids

substances that ionize in aqueous solutions to form hydrogen ions

strong acids

acids that are strong electrolytes, meaning they completely dissociate in water

do we use solubillity rules with acids?

no

strong acid example

hydrochloric acid

strong acid example

hydrobromic acid

strong acid example

hydroiodic acid

strong acid example

nitric acid

strong acid example

sulfiric acid

strong acid example

chloric acid

strong acid example

perchloric acid

weak acids

weak electrolytes, which ionize slightly in water, any besides the seven are weak

pressure

the amount of force that act on a given area

how is pressure measured?

barometers, manometers

barometers

measure atmosphere pressure, mmHg (blood pressure reading!)

manometers

measure pressure of an enclosed glass other than outside atmosphere

ideal gas laws

relationships between four properties of gas laws

directly proportional

a/b= same #

inversley proportional

a*b= same #

P1V1=P2V2

n, T do not change

V1/T1=V2/T2

n, P do not change

P1V1/T1=P2V2/T2

combined gas law

STP

22.4 L- standard temperature and pressure; an assumption of the molar volume of gas

dalton's law of partial pressure

each gas acts as if it is the only one in the container; not affected by presence of other gasses

mole fraction

x1=n1/ntotal; x1=n1/ntotal=p1/ptotal

vapor pressure

as temp increase, vapor pressure increases

KE molar theory of gases

avg. KE of molecules is proportionate to abs. temp; any given temp the gases have the same kinetic energy

in order to have the same avg. kinetic energy,

heavier molecules must have a slower avg. speed

diffusion

collection of molecules by spreading out from high concentration to low

effusion

molecules escape through a hole into a vacuum

graham's law of effusion

relationship of rate of effusion

graham's law equation

rate1/rate2=sq rt (molar gas 1/ molar gas 2)

average speed at STP

molar mass in g

energy

ability to do work or produce heat

work

energy used to move object over distance

heat

transfer of energy b/w 2 objects due to temp difference

joule

unit of energy

calorie

energy unit; energy needed to increase the temp of 1g of liquid water by 1 degree c

potential energy

energy of composition

system

defined as collection of matter we are evaluating

internal energy

system sum of all KE and PE of all components in system

energy flow; exothermic

energy flow; endothermic

law of conservation of energy

energy can be converted from one type to another; E=q+w

state functions

path independent; value of a state function does not depend on how the substance got to that state

enthalpy

dependent on path; H=E+PV

ΔH=Hfinal-Hinitial=Hproducts-Hreactants

heat of reaction

if ΔH is positive

H products>H reactants; heat absorbed by system; reaction requires energy

ΔH is negative

H products

heat capacity

energy required to raise temp of object by 1K or 1C

specific heat capacity

amount of energy required to raise 1g of a substance by 1K or 1C

molar heat capacity

amount of energy required to raise the temp of 1 mol of a substance by 1K or 1C

hess' law

combinig reactions