Thermodynamics (1) Flashcards
what is work ?
energy needed to move force (F) acting in the opposite direction of movement
what is a system ?
what are we interested in ?
what are the surroundings ?
everything else
what is heat ?
energy that moves from high to low temeperature
what is enthalpy (H) ?
used to measure the heat content
(chemical energy) of a substance
what does delta H measure ?
measures changes in enthalpy
equation for delta H
delta H= sum of + pressure bar 1 (products) - sum of + pressure bar 1(reactants)
what does delta H tell us ?
tells us whether a system releases or absorbs heat during the reaction
what is an exothermic reaction ?
a reaction that releases energy to the surroundings so that the temeperature of the substances can rise
what happens to enthalpy in exothermic reactions ?
enthalpy of the system decreases thefore deltaH of an exothermic reaction is always negative
what is an endothermic reaction ?
absorbs heat energy from the surroundings therefore the temperature of the substances may drop
what happens to the enthalpy in edothermic reactions ?
enthalpy of the system increases and so the deltaH is always positive.
