H Chemistry: Unit 6 Flashcards
stoichiometry
quantitative relationship amongst reactants and products in a balanced chemical equation
limiting reagent
reactant that determines the amount of product made(theoretical yield)
excess reactant
reactant that will be left over after the reaction has gone to completion
percent yield
actual yield/theoretical yield x 100
energy
E; ability to do work or produce heat
2 basic forms of energy
potential energy & kinetic energy
potential energy
energy stored in an object based in its position or chemical composition
kinetic energy
energy of motion
1st Law of Thermodynamics
states that energy cannot be created nor destroyed, only converted from one form to another
chemical potential energy
energy stored in chemical compounds that can be released during chemical reactions
2nd Law of Thermodynamics
entropy increases in a closed system
entropy
s; energy that cannot be harnessed to do work; chaos
enthalpy
h; heat content of a system
heat
q; transfer of energy from warmer objects to cooler ones
temperature
average kinetic energy of particles at a given time
delta H
change in enthalpy of a system
endothermic reaction
reaction where energy is added to produce products; +delta H
exothermic reaction
reaction where energy is released when products are formed; -delta H
joule
J; SI unit for heat and energy
kilojoule
kJ; 1000J/1 kJ
calorie
cal; amount of energy required to raise the temperature of 1 gram of water 1 °C
Calorie
nutritional calorie; Cal; kCal; 1000cal/1 Cal
joules to calorie ratio
4.184 J/ 1 cal
specific heat
c; amount of energy required to raise the temperature of 1 gram of any substance 1 °C
specific heat of water
4.184 J/(gx°C)
specific heat equation
q = c x m x delta t
thermochemistry
study of energy changes in chemical reactions and phase changes
delta H of a reaction equation
(delta H of products) - (delta H of reactants)
positive delta H of fusion
melting, solid to liquid
positive delta H of vaporization
boiling, liquid to gas
negative delta H of solidification
freezing, liquid to solid
negative delta H of condensation
gas to liquid
standard enthalpy of formation
the change in energy when one mole of a substance forms
the standard enthalpy of formation of all free elements
0.0 kJ/mol
the standard enthalpy of formation of the reaction
the standard enthalpy of products - reactants
