M4 topic 1: Energy Changes in Chemical Reactions Flashcards
(22 cards)
what is a exothermic reaction
when heat energy is released from the system into the surroundings
what is a endothermic reaction
when heat energy is absorbed from the surroundings
what is temperature
the degree of hotness or coldness of a body
what is temperature measured in
kelvin or Celsius
what is heat
the transfer of thermal energy between objects
what is heat measured in
joules
what is enthalpy
a measure of the total energy possessed by a substance or a group of substances
what is the symbol for change in enthalpy
ΔH
what is the change of enthalpy in a chemical reaction
the heat absorbed per mole of a specified reactant or product
what is the equation for change in enthalpy
change in enthalpy(ΔH) = enthalpy of products(Hₚ ) - enthalpy of reactants (Hᵣ)
what is the value of ΔH in a endothermic reaction
positive
what is the value of ΔH in a exothermic reaction
negative
what is specific heat capacity
the amount of energy needed to increase the temperature of a specific quantity of a substance by one degree kelvin
what does specific heat capacity allow us to calculate
the quantity of heat flow from one substance to another
what is the equation for heat flow
q=mcΔT
what is q
heat energy
what is c
specific heat capacity
what is ΔT
change in temperature
what happens when ΔT and q are positive (3)
the substance gained heat
increased in temperature
Exothermic reaction
what happens when ΔT and q are negative (3)
the substance lost heat
decreased in temperature
Endothermic reaction
what is the relationship between heat and the enthalpy of combustion
q= ΔH𝒸
what is calorimetry
the amount of heat released or absorbed by any chemical process
