51 terms

Chemistry Definitions

formula mass
sum of the atomic masses of all atoms in a compound as represented in a chemical formula; measured in amus
empirical formula
chemical formula that gives the simplest whole number ratio of atoms of elements in a compound
percent composition
mass of each element in a coup mound relative to the total mass of the compound; found by dividing the mass of the element by the mass of the compound and multiplying the quotient by 100 percent
Molar volume of gas @ STP
22.4 L
Carbon 12
what the scale for atomic mass is based on
Determine molar mass
add up the molar masses from the periodic table; measured in grams
Solve mass to mass problem
go to grams to moles to moles and back to grams; balance the equation first
limiting reactant
a reactant that is completely used up in a chemical reaction and that therefore determines the maximum amount of a product that can be formed
study of quantitative relationships that can be derived from chemical formulas and equations
Use Stoichiometry
to find nutritional value, measure concentration of pollution in the atmosphere
Hess's La
if a series of reactions are added together the enthalpy change for the net reaction will be the sum of the enthalpy changes for the individual steps
endothermic reaction
reaction that absorbs heat, positive, disassociation
exothermic reaction
reaction that releases heat, negative, solvation
Real gases behave ideally when?
under high temperature and low pressure
characteristics of gases
fill up containers completely, can diffuse, are colorless, exert pressure,
substance that does the dissolving in a solution, is larger than the solute
substance that is dissolved in a solvent to form a solution
making a solution
1. disassociation- particles separate;needs energy
2. solvation- reaction between solvent and solute;energy is released
concentration of a solution determined by the number of moles of a solute over kilogram of solvent
Pressure only effects
the solubility of gas in liquids
what does adding solute do to the colligative properties?
lowers vapor pressure, raises boiling point, lowers freezing point
constant @ equilibrium
the rate of the forward reaction and the reverse reaction/concentrations of reactants and products
dynamic equilibrium
reaction recaches equilibrium but reactants are still reacting
only factor that will change the value of the equilibrium constant?
large equilibrium constant
the products are favored
equilibrium smaller than one
the reactants are favored
Arrhenius acid
acid dissociates in water to produce Hydrogen ions
Arrhenius base
base dissociates in water to produce hydroxide ions
Strong Acids
HCl, HBr, HI, HNO3, H2SO4, HClO4
law of conservation of mass
mass cannot be created nor destroyed in any process
specific heat
amount of heat energy required to raise the temperature of 1 gram of a substance by 1 degree celsius
heat capacity
amount go heat energy needed to raise the temperature of a given sample of matter by 1 degree Celsius
calorimetry purpose
to determine the heat of a reaction
Boyle's Law
Charle's Law
Gas volume increases
Pressure decreases
temperature increases
volume of gas increases
movement of atoms or molecules through an opening so tiny that they pass through one particle at a time into an evacuated chamber
elastic collisions
collide without slowing down or losing energy
1 atm 273 k
homogenous mixture of two or more substances in a simple physical state
oil and water don't mix because
oil is polar and water is polar, this makes them immiscible
factors that effect dissolving rate
surface area, stirring, temperature
Raoult's Law
magnitude of vapor pressure reduction is proportional to solute concentration
solid solution in which the atoms of two or more metals are uniformly mixed
shift to the left
ability of a liquid to form a solution with another liquid in all proportions
ability of a substance to dissolve in another substance
heterogenous equilibrium
equilibrium condition for a reaction in which all the reactants and products are in two or more different states
Le Chatelier's principle
a reversible reaction at equilibrium will shift to offset a stress or change in conditions imposed on the system
pH equation