chem end of freshmen year final Flashcards
dozen
12
ream of paper
500 sheets
why is it useful to use units like dozen or ream
it determines how many items make up a particular unit.
gross of pencils
144 pencils
mole
SI unit of measurement for chemicals, a specific quantity that doesnt change. ( for atoms, molecules, ions or furmula units)
unit of mol:
mol
symbol of mol
n
Avogagdro’s number
number of things in 1 mole = 6.022 × 10²³
representative particles of elements
atoms
representative particles of covalent compounds
molecules
representative particles of ionic compounds
formula units
a mole is a collection of
6.022 × 10²³
molar mass
mass of one mole of any substance in gram
unit of molar mass
gram per mol (gl/mol)
how is molar mass of element found
by looking at the atomic mass of the element on the periodic table.
another names for molar mass
relative atomic mass (RAM), relative molecular mass (RMM), gram formula mass (gfm), formula mass, molar mass, molecular weight.
the equal of any element’s molar mass
its atomic mass
molar mass of a chemical compound
= to the sum of the molar masses of all the atoms in 1 molecule of that compound
molar mass’s relation to avogadro’s constant
molar mass = mass of 6.022 × 10²³ particles
relationship between the number of moles and the mass of a substance
number of moles x molar mass = mass of a substance
Actication energy (Ea)
the energy needed to get a reaction started
what do reactant molecules need when they collide to form products
energy equal or more than Ea
transition state
a temporary stage when all bonds in the reactants are broken and the atoms are ready to form new bonds. proucts.
∆H
enthalpy change, heat absorbed or released during a reaction
∆H in endothermic reactions
positive
∆H in exothermic reactions
negative
heat in a chemical equation
Reactant in endothermic reactions, product in exothermic reactions
Ea’
activation energy for reverse reaction.
energy
ability to do work or produce heat
universe’s 3 components
matter. energy. empty space / vaccum
how is energy detected
only because of its effects since it has no mass nor volume
thermochemistry
the study of energy changes that occur during chemical reactions and changes in state
flow of heat
always from warmer to cooler objects
unit of energy
Kilojoule (Kj)
enthalpy
the heat content of a system at a constant pressure
3 factors that affect thermal energy
mass, type of substance, temprature change ∆T
calculation for calculating heat
q=c x m x ∆T
specific heat capacity (c)
the amount of heat it takes to raise the temp of 1 gram of a substance by 1°C
∆T
Tfinal - Tinitial
specific heat capacity of water
4.19 j/g°C
qppqratus used to measure enthalpy change
calorimeter
types of reactions
exothermic, give out heat. endothermic, take in heat.
exothermic reaction / equation
reactants → products + heat energy
endothermic reaction / equation
reactants + heat energy → products
components of enthalpy profile diagram
Eac
R
Ea
P
∆H
Ea’
equation to find Eac
Ea + Er
equation to find ∆H
Ep-Er
equation to find Ea
Eac - Er
equation to find Ea’
Eac - Ep
