Chemistry Definitions

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51 terms

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

stoichiometry

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,

solvent

substance that does the dissolving in a solution, is larger than the solute

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

molality

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?

temperature

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

P1V1=P2V2

Charle's Law

...

Gas volume increases

Pressure decreases

temperature increases

volume of gas increases

effusion

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

STP

1 atm 273 k

solution

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

alloy

solid solution in which the atoms of two or more metals are uniformly mixed

Q>Eq

shift to the left

miscible

ability of a liquid to form a solution with another liquid in all proportions

soluble

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

PH=-[concentration]

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