Final Exam Vocab

stoichiometry
the study of the quantitative, or measurable relationships that exist in chemical formulars and chemical reactions
coefficients
in a balanced equation they indicate the number of particles of each substance taking part in the reaction
mole-mole problems

converting from moles of one substance to moles of another

categories of stoichiometry problems

mass-mass

mass-volume

volume-volume

mass-mass problem

and steps involved

you are given the mass of one substance to find the mass of another substance involved in the same reaction. 

 

steps:

  1. convert the amount of the given substnace to moles using molar mass 
  2. use molar ratio to determine moles of unknown
  3. then convert that # to mass using molar mass

 

mass-volume problems

and steps involved

given the mass and asked to find the volume of a gas

 

steps:

  1. convert given mass to moles
  2. then use molar ratio of given to find moles of unknown
  3. convert to volume using molar volume of a gas (22.4 L/mol)

volume-volume problems

like mole-mole problems, given a volume asked to find the unknown volume

 

steps:

  1. take given volume in liters
  2. multiply by ratio

stoichiometric proportions

qhen quantities of reactants are available in the exact ratio described by the balanced equation

 

means no reactants will be left over!

the quantities of products formed in a reaction is determined by?
the quantity of limiting reactant
expected yield
the amount of product that should be produced based on calculations
actual yield
the amount of a product that is really obtained from a chemical reaction
percent yield
what percent of the expected yield was acutally obtained

to find: divide the actual over expected yield and multiply by 100%

thermochemistry
the study of the changes in heat in chemical reactions
exothermic reaction
reaction that releases heat
endothermic reaction
reaction that absorbs heat
enthalpy
the heat absorbed or released in a reaction depends on the difference in quantity of _____
standard enthalpy change
an enthalpy change that is measured when reactants in their standard states change to products in their standard states
Hess’s law
states that if a series of reactions are added together, the enthalpy change for the reaction will be the sum of the enthalpy changes for the individual steps
heat of fusion
the enthalpy change for the melting of ice
heat of vaporization
the enthalpy change for the vaporization of water
calorimetry
the study of heat flow and heat measurement
heat capacity
the amount of heat needed to raise the temperature of the object by 1 celsius degree
specific heat
the heat capacity of 1 gram of a substance
4.184 J/g x C
the specific heat of liquid water
heat
the transfer of kinetic energy from a hotter object to a colder object
condensed states
liquids and solids are referred to this because substances in these states have substantially higher densities than they do in the gaseous state
intermolecular forces
the forces of attraction between neighboring molecules
intramolecular
forces that exist inside the molecule; covalent bonds consist of them
induced dipole
a dipole that is created by the presence of a neighboring dipole
dispersion force
when dipoles are induced and their is a negative end of the dipole of one atom being next to the positive end of another dipole.
dipole-dipole forces
attractions between opposite charges of neighboring dipoles
viscosity
the friction or resistance to motion, that exists between the molecules of a liquid when they move past each other
surface tension
the imbalance of forces at the surface of a liquid results in a property
crystalline solid
a solid in whihc the representative particles ezist ina highly ordered repeating pattern
unit cell
a minimal, repeating unit. as small as possible while accurately representing the pattern
amorphous solids
substances that are rigid and appear solid but do not behave like crystaline solids.
covalent-network solids
the covalent bornds form a network extending throughout the solid crystal whihc have high melting points correponding to the breaking of strong covalent bonds
phase change/change of state
the conversion of a substance from one of the three physical states of matter to another. there is always a change in energy.
vaporization
the change of state from liquid to gas
condensation
chage of state from gas to liquid
evaporation
the process by which molecules of a liquid escape from the surface of the liquid and enter the gas phase
equilibrium vapor pressu
pressure exerted by a vapor in equilibrium with its liquid; point at which the number of molecules in the vapor state remains constant
boiling point
the temperature at which the vapor pressure of a liquid becomes equal to the atmospheric pressure
heat of vaporization
the amount of heat necessary to vaporize a given amount of a liquid at its boiling point
freezing point
the temperature at which the solid and liquid forms of a substance exist in equilibrium
heat of fusion
the heat that is necessary to convert a given amount of a solid into a liquid
sublimation
the conversion of a solid directly to a gas
deposition
the reverse transformation of a gas directly into a solid
heating curve
a plot of the temperature of a sample as a function of time.
phase diagram
relates the states of a substance to temperature and pressure
solution
homogenous mixture of two or more substances in a single physical state
particles
atoms, molecules or ions
evenly distributed in a solution or intermingled on the molecular level
will NOT seperate
solute
the substance that is dissolved
soluvent
the substance that does the dissolving
soluble
a substance that dissolves in another substance
insoluble
a substance that doesn’t dissolve in another
alloys
the most common solid solutions that contain two or more metals. They have greater strength, greater resistance to corrosion, and higher melting points that the pure elements from which they are made
miscible
pairs of liquids that can mix in all proportions. (water and ethanol)
immiscible
liquids that cannot mix in any propotions. (water and oil)
aqueous solution
solutions with water as the solvent
electrolyte
a substance that dissolves in water to form a solution that conducts an electric current
concentrated solution
contains a large amount of solute for the amount of solvent
dilute solutions
relatively small amount of solute for the amount of solvent
concentration
the amount of solute ina given amount of solvent or solution. Measured in molarity, molality, and mole fraction.
molarity
number of moles of solute dissolved in each liter of solution
volumetric flask
the best container for making a solution of a precise molarity
molality
the number of moles of solute dissolved in each kilogram of solvent
mole fraction
the number of moles of one component divided by the total number of moles in the solution.
saturated
a solution is _____when it contains as much solute as can possibly be dissolved under the existing conditions of temperature and pressure
unsaturated
a solution that has less than the mazimum amount of solute that can be dissolved
supersaturated
a solution that contains a greater amount of solute than that needed to form a saturated solution. These solutions are very unstable and do not stay this way for a long time.
solvation
the interaction between solute and solvent particles
hydration
the interaction between solute and solvent particles when the solvent is water
solubility
the amount of a solute that will dissolve in a specific solvent under given conditions.
dipole
seperation of charge
polar solvent
a liquid made up of polar molecules
nonpolar solvent
a liquid made up of nonpolar molecules
henry’s law
the solubility of a gas is proportional to the partial pressure of the gas above the liquid
surface area (dissolving)
the dissolving of a solid solute takes place here. Solvent particles pull particles form the surgace of the solute into the solution. This can be speeded up by increasing this.
stirring (dissolving)
a technique frequently used to speed up the solution process. It moves the heavy concentration of dissolved solute away from the surface of the undissolved solute and makes fresh solvent.Basically, contact betwwen the solvent and the solute surface is increased.
temperature (dissolving)
raising this of a solvent increases the rate at which the solute dissolves because solvent particles move faster and more particles come into contact with the solute. Also the solvent particles have more energy to remove particles from the solid solution
colligative property
a property that depeneds on the concentration of solute particles but is independent of their nature.
the four colligative properties
vapor pressure reduction, boiling point elevation, freezing point depression, and osmotic pressure
vapor pressure reduction
the pressure of the vapor over a solvent is reduced when a nonvolatile solute is dissolved in the solvent. Directly related to the concentration of a solution.
osmotic pressure
pressure required to prevent osmosis. happens when the flow of solvent particles from a dilute solution to a concentrated solution across a semipermeable membrane results in uneven heights of the solutions on either side of the membrane.
freezing point depression
property in whihc the freezing point of a solvent is lowered when a nonvolutile solute is dissolved in the solvent. related to concentration of solution
boiling point elevation
boiling point of a solvent is raised when a nonvolatile solute is dissolved in the solvent. related to the concentration of a solution.
isotonic
solutions with identical osmotic pressure. no osmosis
hypotonic
when one solution has a lower osmotic pressure than the other. placing cells in this causes water to move into the cells causing the cells to burst.
hypertonic
when one solution has a higher osmotic pressure. a cell in this has water leave the cells causing the cells to shrivel and die, shrinking
reversible reactions
The chemical reaction in whihc the products can regenerate the original reactants
chemical equilibrium
the rate of the forward reaction is equal to the rate of the reverse reaction. It is the state whihc the concentrations of reactants and products remain constant with time because the rate at whihc they are formed in each reaction equals the rate at which they are consumed in the opposite reaction
law of mass action
expresses the relative concentartions of reactants and products at equilibrum in term of the equilibrium constant
equilibrium constant
Keq is a measure of the extent to whihc a reaction proceeds to completion
equilibrium expression
keq = products of FR/reactants
law of chemical equilibrium
every reversible reaction proceeds to an equilibrium state that has a specific ratio of the concentrations of reacts and products
equilibrium position
depends on the initial concentrations, each set of equilibrium concentrations
homogeneous equilibria
equilibrium conditions for reactions in which all the reactant and products are in the same state
heterogenous equilibria
equilibrium conditions for reactions that involve substances in more than one state
the reaction quotient
Q is used to find our if a reaction is at equilibrium. The concentrations that exist at the time the measurement is taken, not the equilibrium concentrations
le chatelier’s principle
if a change in conditions is imposed on a system at equilibrium the equilibrium position will shift in the direction tends to reduce that change in conditions
Q < Keq
shifts to the right
Q > Keq
shifts to the left
haber process
an industrial process in which ammonia is synthesized. uses le chateliers principle to maximize the yield of ammonia
dissolution
the process in which an ionic solid dissolves in a polar liquid
precipitation
the process in which ions leave a solution and regenerate an ionic solid
solubility equilibrium
when dissolution and precipitation occur at the same rate and the saturated solutions of ions and the remaining solid are in chemical equilibrium.
solubility product
Ksp
ion product
Q is used to compare the solubility product to determine if an aqueous solution of ions is supersaturated and will form a precipitate.
precipitation reactions
a reaction in which two solutions are mixed and a precipitate form. described by balanced equations
sparingly soluble substance
insoluble
complete ionic equation
an equation that shows all soluble ionic substances as ions
spectator ions
ions that do not take part in a chemical reaction and are found in solution both before and after the reaction.
net ionic equation
only those compounds and ions that undergo a chemical change in a reaction in an aqueous solution
common-ion effect
a shift in equilibrium that occurs because the concentration of an ion that is part of the equilibrium has changed
indicator
a substance that turns one color in an acidic solution and another color in a basic solution
neutralization reaction
the reaction between an acid and a base, where the acid neutralizes the base and vise versa
hydronium ion
H3O + the complex an H+ ion forms with water
amphoteric
a substance such as water that can act as either an acid or a base depending on the circumstances
conjugate acid
when a base gains an H+ ion it becomes this
conjugate base
when an acid loses an H+ ion it becomes this
the acid dissociation constant
Ka the measure of the strength of an acid
the greater the stronger it is
base dissacoiation constant
the strength of a base
Kb
salt hydrolysis reactions
the reactions of ions from salts to form H3O+ or OH -1 ions
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