Enthalpy Flashcards
what is enthalpy represented by
H
what does enthalpy relate to
the bonds made and broken in a chemical reaction
what is H1 in a reaction
the reactants
what is H2 in a reaction
products
what is ∆H
the change in enthalpy
what = ∆H (whats the equation for ∆H)
∆H = enthalpy of products - enthalpy of reactants
(or)
∆H = H2 - H1§
is ∆H +ve or -ve for an endothermic reaction
∆H is +ve
is ∆H +ve or -ve for an exothermic reaction
∆H is -ve
Can enthalpy be measured or calculated
no but enthalpy changes can be
what would happen to ∆H if the reaction was reversible
the number for ∆H would be the same the sign would have changed from + to - or visa versa
what is a reaction profile
it is a diagram of the enthalpy levels of the reactants and products in a chemical reaction
what does the vertical axis (y) represent on a reaction profile
it is enthalpy but not ∆H
what does the horizontal axis (x) represent on a reaction profile
it is progress of the reaction, reaction coordinate or extent of reaction
is the product line higher or lower on a reaction profile in an endothermic reaction
higher
is the product line higher or lower on a reaction profile in an exothermic reaction
lower
what is the difference between the product line and the reactant line in a reaction profile
∆H
what is ∆H for an endothermic reaction
+ve
what is ∆H for and exothermic reaction
-ve
how is the reaction pathway shown on a reaction profile
it is shown by a line from the reactants to products on a reaction profile
what is the reaction pathway
the route in terms of enthalpy from reactants to products
what is required in reaction pathways before new bonds can form in the products
an input of energy to break bonds
where is the activation energy in a reaction profile
the maximum height of the pathway above the enthalpy level of the reactants
what are standard conditions represented by
the symbol ⦵
where is the symbol ⦵ used
after ∆H to show that the reaction is conducted under standard conditions
